Erysiphe Necator Resistance Providing Genes in Vitis Vinifera

Abstract

Provided herein are Erysiphe necator resistance conferring genes, plants, plant parts and seeds comprising the present resistance providing genes and the use thereof for selecting Erysiphe necator resistant plants. Specifically, provided herein are Erysiphe necator resistance conferring genes, wherein the amino acid sequence encoded by said resistance conferring genes is the primary amino acid sequence represented SEQ ID No. 1, or a primary amino acid sequence with more than 70% identity, preferably more than 80% identity, more preferably more than 90% identity, and most preferably more than 95% identity with SEQ ID No. 1; and wherein said resistance conferring gene is impaired.

Description

[0001] The present invention relates to Erysiphe necator resistance conferring genes, plants, plant parts and seeds comprising the present resistance providing genes and the use thereof for selecting Erysiphe necator resistant plants.

[0002] Erysiphe necator, also designated as Uncinula necator, is a fungus causing powdery mildew disease symptoms in grape. The fungus is a common pathogen for Vitis species of which the most important species is Vitis vinifera or grapevine.

[0003] Grapevine requires a huge amount of pesticides, particularly fungicides, to prevent yield losses. Between 1992 and 2003, 73% of the fungicides sold in France, Italy, Spain and Germany, were used for grapevine protection, a crop that covers only 8% of the land used for agriculture in the considered countries (EUROSTAT, 2007).

[0004] Grapevine powdery mildew (PM) caused by the fungus Erysiphe necator, is one of the most economically relevant diseases of grapevine worldwide. E. necator is an obligate biotroph that can infect all green tissues of grapevine and causes significant losses in yield and berry quality. PM symptoms are a white or grey powder covering of the upper and lower surfaces of the leaves. Fruit infections result in shriveling or cracking of the berries. The quality of the fruit is severely damaged, with increased acidity and decreased anthocyanin and sugar content.

[0005] Powdery mildew is controlled with frequent applications of chemical fungicides. However, the intense application of chemical fungicides has several drawbacks. First of all, the effects on environment of fungicides are well documented. Secondly, the costs of the chemicals and their applications can reach up to 20% of the total expenses for grape production in some areas. Thirdly, the development of resistant populations of the pathogen was already documented by Baudoin et al. (2008) and Dufour et al. (2011), strongly reducing the efficacy of chemical treatments. Therefore, there is increasing interest in the development of new alternative methods to chemical treatments.

[0006] The generation of PM-resistant varieties is one of the best options to make sustainable grapevine cultivation a realistic possibility, preserving at the same time the incomes of the growers. A study carried out on "Chardonnay" production in California, showed that the use of PM-resistant variety could save to the growers around 720 $/ha, with a significant reduction of fungicide usage (Fuller et al., 2014).

[0007] Most cultivars of the European grapevine (Vitis vinifera), which includes the world's finest and most widely planted wine and table grapevine cultivars, are highly susceptible to PM (Gadoury et al. 2003). In contrast, North American Vitis species co-evolved with E. necator and possess various level of resistance to the pathogen (Fung et al., 2008). This resistance could be introgressed by crossing V. vinifera with one of the resistant American Vitis species, but breeding is a slow process in grapevine and the acceptance of resistant hybrids by producers and consumers has been limited in the past (Fuller et al., 2014). The use of technologies like genetic transformation or high-throughput marker-assisted selection can be used to obtain resistant grapevine cultivars with desirable grape properties for producers and consumers (Feechan et al., 2013a).

[0008] The most common strategy to develop resistant plants is focused on the introgression of resistance genes (R-genes). R-genes encode proteins that recognize pathogen effectors and trigger defense response, mediated by a signaling network in which plant hormones play a major role (Pavan et al., 2010). Resistance is manifested as localized hypersensitive response at the site of infection (Bari and Jones, 2009). Resistance conferred by R-genes is scarcely durable, as mutations of pathogen effectors, allow it to overcome resistance (Parlevliet et al., 1993).

[0009] An alternative approach is based on the inactivation of susceptibility genes (S-genes), defined as genes whose loss-of-function results in recessively inherited resistance (Pavan et al., 2010). Some pathogens are able to suppress plant defense by activating plant proteins which function is the negative regulation of plant immunity system. The genes encoding these plant proteins are known as susceptibility genes (S-genes) and their knock-out release the suppression of plant defense and lead to resistance (Pavan et al., 2010). The disadvantage of S-genes is the pleiotropic phenotypes sometimes associated to their knock-out (Pavan et al. 2011). Mildew Locus O (MLO) genes are a typical example of PM S-genes.

[0010] Resistance due to the knock-out of an MLO gene (mlo resistance) was discovered in barley in 1992 (Jorgensen, 1992) and for a long time was considered as a unique form of resistance. However, further studies revealed that MLO genes are largely conserved across plant kingdom and their loss-of-function resulted in resistance in several species, such as Arabidopsis (Consonni et al., 2006), pea (Pavan et al., 2011), tomato (Bai et al., 2008) and pepper (Zheng et al., 2013). Not all MLO genes are S-genes and MLO family members are divided in seven clades (Acevedo-Garcia et al., 2014; Pessina et al., 2014). Only two clades contain S-genes: clade IV contains all monocots S-genes (Panstruga et al., 2005; Reinstadler et al., 2010); and clade V contains all dicots S-genes (Consonni et al., 2006; Bai et al., 2008; Feechan et al., 2008; Winterhagen et al., 2008). Not all the members of clades IV and V are S-genes.

[0011] Considering the economic impact of an Erysiphe necator infection on grape production, there is a continuing need in the art for Erysiphe necator resistance providing genes.

[0012] It is an object of the present invention, amongst other objects, to meet this need of the art.

[0013] According to the present invention, the above object, amongst other objects is met by providing impaired Erysiphe necator resistance providing genes as outlined in the appended claims.

[0014] Specifically, the above object, amongst other objects, is met according to a first aspect of the present invention by providing Erysiphe necator resistance conferring genes, wherein the amino acid sequence encoded by the resistance conferring gene is the primary amino acid sequence represented by SEQ ID No. 1, or a primary amino acid sequence with more than 70% identity, preferably more than 80% identity, more preferably more than 90% identity, and most preferably more than 95% identity with SEQ ID No. 1 under the condition that the present resistance conferring genes are impaired.

[0015] In the alternative, the above object, amongst other objects, is met according to a first aspect of the present invention by providing Erysiphe necator resistance conferring genes, wherein the amino acid sequence encoded by the resistance conferring gene is the primary amino acid sequence represented by SEQ ID No. 2, or a primary amino acid sequence with more than 70% identity, preferably more than 80% identity, more preferably more than 90% identity, and most preferably more than 95% identity with SEQ ID No. 2 under the condition that the present resistance conferring genes are impaired.

[0016] As yet another alternative, the above object, amongst other objects, is met according to a first aspect of the present invention by providing Erysiphe necator resistance conferring genes, wherein the amino acid sequence encoded by the resistance conferring gene is the primary amino acid sequence represented by SEQ ID No. 3, or a primary amino acid sequence with more than 70% identity, preferably more than 80% identity, more preferably more than 90% identity, and most preferably more than 95% identity with SEQ ID No. 3 under the condition that the present resistance conferring genes are impaired.

[0017] Sequence identity as used herein is defined as the number of identical consecutive aligned nucleotides, or amino acids, over the full length of the present sequences divided by the number of nucleotides, or amino acids, of the full length of the present sequences and multiplied by 100%. For example, a sequence with 80% identity to SEQ ID No. 1 comprises over the total length of 539 amino acids of SEQ ID No. 1, 431 or 432 identical aligned amino acids, i.e., 430 or 431/539*100%=80%.

[0018] An impaired resistance conferring gene according to the present invention is meant to indicate a gene providing a reduced, or even absent, susceptibility to Erysiphe necator as indicated by powder-like spots on the leaves and stems.

[0019] Impaired resistance conferring genes according to the present invention are mutated genes. The mutation, or mutations, in the present genes can results/result in impairment by different mechanisms. For example, one or more mutations in protein encoding DNA sequences can result in mutated, truncated or non-functional proteins. One or more mutations in non-coding DNA sequences can cause alternative splicing, translation or protein trafficking. Alternatively, one or more mutations resulting in an altered transcriptional activity of a gene, which determines the amount of mRNA available for translation to protein, can result in a resistance due to a low level, or complete absence, of encoded proteins. Additionally, the impairment of the present genes may be caused after translation, i.e. at protein level.

[0020] Impaired is also indicated herein as encoding a non-functional gene or protein. Although the function of the present genes is not yet identified, a non-functional gene or protein can be readily determined by establishing Erysiphe necator resistance (non-functional) or Erysiphe necator susceptibility (functional) in a plant. An Erysiphe necator resistance (non-functional) plant is indicated by comprising a gene which is mutated at the protein level as compared to the SEQ ID Nos. 1 or 2 or 3 or reduced levels are observed of mRNA comprising SEQ ID Nos. 4 or 5 or 6.

[0021] Functional and non-functional genes, or proteins, can also be determined using complementation experiments. For example, transforming an Erysiphe necator resistant Vitis vinifera plant with a copy the present genes under the control a constitutive promoter will result in an Erysiphe necator susceptible Vitis vinifera plant.

[0022] According to the present invention, the present Erysiphe necator resistance conferring genes provide Erysiphe necator resistance when impaired. Impaired according to the present invention can be indicated by the absence, or decrease of a protein identified herein by SEQ ID Nos. 1 or 2 or 3. In the art, many mechanisms are known resulting in the impairment of a gene either at the transcription, translation or protein level.

[0023] For example, impairment at the transcription level can be the result of one or more mutations in transcription regulation sequences, such as promoters, enhancers, initiation, termination or intron splicing sequences. These sequences are generally located 5' of, 3' of, or within the coding sequences represented by SEQ ID Nos. 4 and 5 and 6. Impairment can also be provided by a deletion of, rearrangement of or insertion in the present genes.

[0024] Impairment at the translation level can be provided by a premature stop-codons or other RNA to protein controlling mechanisms or post-translational modifications influencing, for example, protein folding or cellular trafficking.

[0025] Impairment at the protein level can be provided by truncated, misfolded or disturbed protein-protein interactions.

[0026] Independent of the underlying mechanism, impairment according to the present invention is indicated by a decrease, or absence, a functional protein according to SEQ ID Nos. 1 or 2 or 3.

[0027] Considering the above, according to an embodiment of the first aspect of the present invention, impairment according to the present invention comprises one or more mutations in the present genes resulting in the absence of a protein expression product with a primary amino acid sequence represented by SEQ ID No. 1 or an mRNA comprising SEQ ID No. 4; or, in the alternative the absence of a protein expression product with the primary amino acid sequence represented by SEQ ID No. 2 or 3 or an mRNA comprising SEQ ID No. 5 or 6, respectively.

[0028] According to another embodiment of this first aspect of the present invention, the present impairment comprises one or more mutations in the present genes resulting in a non-functional protein expression product.

[0029] According to still another embodiment of this first aspect of the present invention, the present impairment comprises a reduced transcription level resulting in a reduced level of an mRNA comprising SEQ ID No. 4 or SEQ ID No. 5 or SEQ ID No. 6.

[0030] According to yet another embodiment of this first aspect of the present invention, the present impairment comprises a reduced translation level of an mRNA comprising SEQ ID No. 4 or SEQ ID No. 5 or SEQ ID No. 6.

[0031] According to an especially preferred embodiment of the invention, the present Erysiphe necator resistance conferring gene is derived from Vitis vinifera.

[0032] According to a second aspect, the present invention relates to Vitis vinifera plants comprising in their genome an impaired Erysiphe necator resistance conferring gene as described above wherein the impairment provides Erysiphe necator resistance.

[0033] According to a preferred embodiment of this second aspect of the present invention, the present Vitis vinifera plants show an expression, or transcription, of the present Erysiphe necator resistance conferring genes being reduced by at least 10% as compared to a Vitis vinifera plant susceptible to Erysiphe necator, preferably wherein the expression, or transcription is reduced by at least 20% as compared to a Vitis vinifera plant susceptible to Erysiphe necator, preferably at least 30%, more preferably at least 50%, even more preferably at least 70%, and most preferably at least 80% such as 25%, 35%, 40%, 45%, 55%, 60%, 65% or 75%.

[0034] According to another preferred embodiment of this second aspect of the present invention, the present Vitis vinifera plants display an absent expression, or transcription of the present Erysiphe necator resistance conferring genes.

[0035] According to an especially preferred embodiment of this second aspect of the present invention, the present Vitis vinifera plants comprise in their genome an impaired Erysiphe necator resistance conferring gene encoding a protein with the primary amino acid sequence of SEQ ID No. 1, or a primary amino acid sequence with more than 70% identity, preferably more than 80% identity, more preferably more than 90% identity, and most preferably more than 95% identity with SEQ ID No. 1; and, in addition, an impaired Erysiphe necator resistance conferring gene encoding a protein with the primary amino acid sequence of SEQ ID No. 2, or a primary amino acid sequence with more than 70% identity, preferably more than 80% identity, more preferably more than 90% identity, and most preferably more than 95% identity with SEQ ID No. 2; and/or an impaired Erysiphe necator resistance conferring gene encoding a protein with the primary amino acid sequence of SEQ ID No. 3, or a primary amino acid sequence with more than 70% identity, preferably more than 80% identity, more preferably more than 90% identity, and most preferably more than 95% identity with SEQ ID No. 3. Formulated differently, the present invention relates according to an especially preferred embodiment to Vitis vinifera plants comprising an impaired VvMLO7 gene in combination with an impaired VvMLO6 or VvMLO11 gene or comprising an impaired VvMLO7 gene in combination with impaired VvMLO6 and VvMLO11 genes.

[0036] According to a third aspect, the present invention relates to seeds, plant parts or propagation material of the present Erysiphe necator resistant plants comprising in their genome the present one or two impaired Erysiphe necator resistance conferring genes providing Erysiphe necator resistance.

[0037] According to a fourth aspect, the present invention relates to isolated nucleotide sequences represented by SEQ ID Nos. 4 or 5 or 6, or nucleotide sequences with more than 70% identity, preferably more than 80% identity, more preferably more than 90% identity, and most preferably more than 95% identity therewith.

[0038] According to a fifth aspect, the present invention relates to isolated amino acid sequences represented by SEQ ID No. 1 or 2 or 3, or amino acid sequences with more than 70% identity, preferably more than 80% identity, more preferably more than 90% identity, and most preferably more than 95% identity therewith.

[0039] According to a sixth aspect, the present invention relates to the use of the present Erysiphe necator resistance conferring genes, the present isolated nucleotide sequences or the present isolated amino acid sequences for selecting an Erysiphe necator resistant Vitis vinifera plants using, for example, the present sequences for developing molecular markers.

[0040] The present invention will be further detailed in the following example of an especially preferred embodiment of the present invention. In the example, reference is made to figures wherein:

[0041] FIG. 1: shows the area under disease progress curve (AUDPC) of grapevines inoculated with Erysiphe necator in control (EVB) and transgenic lines (TLB1, TLB2, TLB3, TLB4, TLB5, TLB6 and TLB7). The mean scores of AUDPC values calculated on 8-19 biological replicates from two experiments are reported. Error bars show standard error of the mean. The asterisks indicates statistically significant differences respect to the control line EVB, according to Tukey or Games-Howell post-hoc tests (P=0.05). Pictures of representative leaves for each line were collected 30 days after inoculation.

[0042] FIG. 2: shows Germination of Erysiphe necator conidia in the control line EVB (A) and in the resistant transgenic line TLB4 (B). Microscopy images of infected leaves were taken at 3, 10 and 21 days post inoculation (dpi) with powdery mildew. Insert at high magnification highlighted the germination of an Erysiphe necator conidia at 3 dpi and 10 dpi.

[0043] FIG. 3: shows formation of papillae in the control line EVB (A, B) and in the resistant transgenic line TLB4 (C, D). Microscopy images taken with a bright field (A, C) and fluorescence (B, D) microscope at three days post inoculation (dpi). The arrows indicate the papillae (P). The scale bar is the same for the four images.

[0044] FIG. 4: shows gene expression of four grapevine MLO genes in the six mlo lines (TLB1, TLB2, TLB3, TLB4, TLB5, and TLB6) following inoculation with Erysiphe necator. Expression of VvMLO6 (A), VvMLO7 (B), VvMLO11 (C) and VvMLO13 (D) was analyzed before (0 dpi; light grey), one (dark grey), and ten (white) days post inoculation. The mean scores calculated from five to nine plants pooled from the two experiments are reported for each line. Error bars show standard error of the mean. For each time point, symbols highlight significant differences respect to the control EVB, according to Tukey or Games-Howell post-hoc test (P=0.05): * for 0 dpi, + for 1 dpi and # for 10 dpi.

[0045] FIG. 5: shows relative expression of 13 grapevine genes at three time points in the control line EVB and in the resistant line TLB4. The color scale indicates the relative expression values calculated respect to the control EVB at 0 dpi, used as reference for data normalization. The asterisks highlight statistically significant differences according to Fisher post-hoc test. One and two asterisks indicate significance at P=0.05 and P=0.01, respectively. The image was prepared with the Multiexperiment Viewer software with the Log 2 of relative expression data

EXAMPLE

Materials and Methods

Constructs for Grapevine Transformation

[0046] Fragments of 300-600 bp for the four MLO target genes VvMLO6, VvMLO7, VvMLO11 and VvMLO13 were amplified with specific primer pairs (Table 1) and cloned into the vector pENTR/SD-TOPO (Invitrogen).

TABLE-US-00001 TABLE 1 Primers used to amplify MLO genes fragments for the RNAi constructs. Gene.sup.# Primer Forward Primer Reverse VvMLO6 CACCTGCTTACAGTATTACAAACTCCC TTTCCCTTGCATACCTAAAC VvMLO7 CACCGACAATTTTTAACGAGAGAGT ATCTCATGTTGGGTTCGGATT VvMLO11 CACCTCACTTATGCTACTGGGGTT ATCAACTTTGGGAACTGATCTGAC VvMLO13 CACCGAGCTAATGTTGCTAGGGTT AAATTTTGCATGGCTTTGAG

[0047] After sequence validation, the four gene fragments were cloned in the RNAi Gateway vector pK7GWIWG2D(II) (Karimi et al. 2002; http://www.psb.ugent.be/) using the procedure described by Urso et al. (2013). The final constructs were verified by sequencing on both strands and were cloned into Agrobacterium tumefaciens strain GV3101, as described by Zottini et al. (2008). A. tumefaciens-transformed cells were tested by PCR (GoTaq Green Master Mix--Promega, Fitchburg, USA) to confirm the presence of the constructs using specific primers designed to anneal on the 35S promoter (5'-CGCACAATCCCACTATCCTT-3') and the MLO fragment (Table 1).

Plant Material and Transformation

[0048] For grapevine transformation, somatic embryos of V. vinifera cultivar Long-Cluster Brachetto were used. The plant material was in vitro cultivated in the darkness in a growth chamber at 20-24.degree. C. and 70.+-.5% relative humidity (RH). Plant transformation, regeneration and selection of the transgenic plants were carried out as described by Dalla Costa et al. (2014). A total of five transformations were performed: four aimed to silence the four MLO target genes, one with an empty vector (pK2WG7), as control.

Screening of Regenerants and Propagation of In Vitro Materials

[0049] Genomic DNA was extracted from in vitro leaf tissue using Illustra Nucleon Phytopure kit (GE Healthcare, Buckinghamshire, UK). Transgene integration was evaluated with the same primers used to confirm the presence of the construct in A. tumefaciens. The in vitro lines that were confirmed to have the insertion of the transgene were moved to a woody plant (WP) medium (McCown and Lloyd, 1981), kept in growth chamber (20-24.degree. C., 70.+-.5% RH) and transferred in fresh media once a month.

Greenhouse Acclimation

[0050] Plants were acclimated to greenhouse conditions with a progressive process carried out in a growth chamber (25.degree. C., 16 hours day/8 hours night, humidity 70.+-.5%). One-month old-plants with a well-developed root apparatus (at least two main roots, 3 cm long) were transferred in a 250 ml plastic cup containing wet autoclaved turf (Terriccio Vegetal Radic--Tercomposti Spa, Brescia, Italy) and sealed with parafilm, to preserve humidity. Every seven days, one or two holes were made in the parafilm layer, to progressively reduce the humidity of the environment and promote the formation of the foliar cuticle. After three weeks, the parafilm sealing was completely removed and, after one week, plants were transferred into 1 L pots and grown under greenhouse conditions (25.degree. C., 16 hours day/8 hours night, humidity 70.+-.5%).

Erysiphe necator Inoculation and Disease Severity Assessment

[0051] The PM inoculum was obtained from infected leaves of an untreated vineyard in northern Italy (Trentino region) and maintained by subsequent inoculations on V. vinifera "Pinot Noir" plants under greenhouse conditions. The plants were dry inoculated with PM by gentle brushing from infected young leaves carrying freshly sporulation E. necator onto the target leaves (Blaich et al., 1989). Inoculated plants were incubated in the greenhouse at 25.degree. C. with a relative humidity (RH) of 100% for 6 h to promote the fungal penetration into the leaves, and then maintained at 25.degree. C. with a relative humidity of 70.+-.10% until the last symptom's evaluation. Disease severity was visually assessed on all leaves at 14, 22 and 30 days post inoculation (dpi), according to the standard guidelines of the European and Mediterranean Plant Protection Organisation (EPPO, 1998).

[0052] Disease severity was expressed as the proportion (percentage of 0 to 100%, with intervals of 5%) of adaxial leaf area covered by PM mycelia in relation to the total leaf area, and a mean value was calculated for each plant. Two inoculation experiments were carried out. For each experiment, three to nine biological replicates (plants) per line were analyzed in a randomized complete block design. The reduction of disease severity was calculated according to the following formula: [(disease severity in control plants--disease severity in treated plants)/disease severity in control plants].times.100. To analyze all the time points together, we used the area under disease progress curve (AUDPC), a quantitative summary of disease intensity over time (Campbell and Madden, 1990; Madden et al., 2007).

[0053] To evaluate the disease severity, the number of E. necator conidia produced from infected leaves was assessed as described by Angeli et al. (2012) with slight modifications. Three leaves were collected from each replicate at 30 dpi and four disks of 0.8 cm diameter for each leaf were cut for a total of 12 disks for replicate. Leaf disks were transferred to 50 mL tubes containing 5 mL distilled water with 0.01% Tween 80 (Sigma-Aldrich, Saint Louis, USA). Tubes were vortexed for one min and the concentration of conidia per ml was determined by counting with a haemocytometer under a light microscope. The amount of conidia was finally converted in conidia per square centimeter (cm.sup.2) of grapevine leaf.

Histological Analysis

[0054] Two inoculated leaves were collected from three biological replicate of each transgenic and control line at 3, 10 and 21 dpi and subjected to histological analysis. To visualize fungal hyphae, leaves were cleared and stained as described by Vanacker et al. (2000) changed as follow: leaves were cut in small pieces and laid with the adaxial surface up on filter paper moistened with an ethanol:glacial acetic acid mixture (3:1, v/v) until the chlorophyll had been removed. Leaf pieces were transferred to water soaked filter paper for 2 h, then transferred on a microscope slide and a drop of aniline blue (0.1% [w/v] in lactoglycerol) was pipetted onto leaf surface. Hyphae were visualized using the bright field illumination of a Leica LMD6500 microscope (Leica Microsystems, Wetzlar, Germany).

[0055] For the detection of papilla, leaves were cleared in an ethanol:glacial acetic acid mixture (3:1, v/v) until the chlorophyll had been removed, and equilibrated overnight in a solution containing lactic acid, glycerol and water (1:1:1). Papillae were visualized using the LMD filter (BP filter 380-420 nm excitation, 415 dichroic mirror, and BP 445-485 nm emission) of a Leica LMD6500 microscope (Leica Microsystem, Wetzlar, Germany).

Sample Collection, RNA Extraction and Gene Expression Analysis

[0056] The first gene expression analysis was carried out on in vitro transgenic plants, to identify silenced lines, with three biological replicates collected. For the second analysis, carried out on acclimated transgenic plants, leaf samples were collected immediately before inoculation, 24 hours and 10 days post PM inoculation. These time points were chosen because are associated with the up-regulation of MLO genes during E. necator infection (Feechan et al., 2008; Winterhagen et al., 2008). For each line at each time point, leaf samples were collected from five different plants. Each sample comprised two half leaves taken from the same plant; only leaves of the third and fifth nodes from the top of the shoot were collected. Samples were immediately frozen in liquid nitrogen and stored at 80.degree. C.

[0057] Total RNA was extracted with the Spectrum.TM. Plant Total RNA kit (Sigma-Aldrich), treated with the DNAse I (Sigma-Aldrich) and reverse transcribed using the SuperScript III reverse transcriptase (Invitrogen, Life Technologies, Waltham, USA).

[0058] The qPCR analysis was performed with Advanced Universal SYBR Green Supermix (Bio-Rad, Hercules, USA) in a 15-4, reaction volume with specific primers (Table 2), using a CFX96 Touch Real-Time PCR detection system (Bio-Rad, Hercules, USA), run by CFX Manager software.

TABLE-US-00002 TABLE 2 Primers used to amplify MLO genes fragments for the qPCR analysis. Name Forward ('5-'3) Reverse ('5-'3) EF1.alpha. GAACTGGGTGCTTGATAGGC AACCAAAATATCCGGAGTAAAAGA GAPDH TTCTCGTTGAGGGCTATTCCA CCACAGACTTCATCGGTGACA Actin TCCTTGCCTTGCGTCATCTAT CACCAATCACTCTCCTGCTACAA VvMLO6 GTGCAGTTATGTGACACTCCC ACACACCATCCGAGTGC VvMLO7 CTTTCTTCGCATGGAGCACG GAGCCCATCTGTGTCACCAA VvMLO11 GCACCCCCTTACATGGC TCTGGACCAGGATTTCTATGATG VvMLO13 CTGGTGACACAGATGGGTTC CTACTTGACATGGGTGTGGC VvWRKY19 GGGGAGGCTGTGGTTAGGTT GTTTGGCATTTGGCTTGTCT VvWRKY27 CTTGGATCAGAATCACCCCTAA GCCGTGGTATGTGGTTTTGTA VvWRKY48 CAAGATTTCAAGGACCAAGCAG AGTATGCCTTCCTCGGTATGT VvWRKY52 CCTCTTGATGATGGGTTTAGTT GTCTTCCACGGTAGGTGATTT VvALS1 CCGTGCATACCGAGCATTTG AGGCCGGTTCTGTATGTTGG VvEDS1 AGGGTTTTATATTGTTATCTCAA GGAAGAAAATATCTTATTACTACATAATG GGC TTTC VvLOX9 GACAAGAAGGACGAGCCTTG CATAAGGGTACTGCCCGAAA VvLOX1 ATCAATGCTCTTGCTCGGGA CCAGAGCTGGTCATAGGCAG VvPAD4 ACGATTGCACTGGTAAGCCA CGACTCCGTCATCGCCTAAA VvPEN1 CTTCGCAAGAAGCTCAGGGA TGCTCTTGGATCGCCTTCTG VvPR1 CCCAGAACTCTCCACAGGAC GCAGCTACAGTGTCGTTCCA VvPR6 ACGAAAACGGCATCGTAATC TCTTACTGGGGCACCATTTC VvNPF3.2 TCGTCACATCAGCACAGCTT ATCTGCGAGCCAATGGAACA

[0059] The software applies comparative quantification with an adaptive baseline. Samples were run in two technical replicates with the following thermal cycling parameters: 95.degree. C. 3 min, followed by 40 cycles of 95.degree. C. 10 sec and 55.degree. C. 30 sec with a final step at 95.degree. C. 10 sec. Primers for gene expression analysis of VvMLO6, VvMLO11 and VvMLO13 were taken from Winterhagen et al. (2008), while for VvMLO7 we designed our specific primer pair (Table 2). Expression of marker genes modulated in the interaction between plants and PM were also analyzed. Primers for VvWRKY19, VvWRKY27, VvWRKY48 and VvWRKY52 were taken from Guo et al. (2014), primers for VvEDS1 from Gao et al. (2014) and primers for VvPR1, VvPR6 and VvLOX9 from Dufour et al. (2013). The new primer pairs were designed with the NCBI Primer Designing Tool (http://www.ncbi.nlm.nih.gov/tools/primer-blast/) (Table 2). Four serial dilutions of cDNA (1/10-1/100-1/1000-1/10000) were used to calculate the efficiency of the primer pairs and the size of the products was confirmed by agarose gel electrophoresis. Presence of a specific final dissociation curve was determined after every qPCR run with progressive increments of temperature from 65.degree. C. to 95.degree. C. (0.5.degree. C. each step, 5 sec).

[0060] The reference genes were Elongation Factor 1.alpha. (GenBank accession number EC959059), GAPDH (GenBank accession number CB973647) and Actin (GenBank accession number AY6807019), known to be reference for grapevine (Reid et al., 2006). In this work the stability of these genes was confirmed using the software GeNorm (medgen.ugent.be/.about.jvdesomp/genorm/). All three reference genes had M-values lower than 0.5, when an M-value lower than 1.5 was generally considered as stable enough (Ling and Salvaterra, 2011; Van Hid et al., 2009; Strube et al., 2008).

[0061] The threshold cycles (Ct) were converted to relative expression with the system proposed by Hellemans et al. (2007), using as input the average Ct of two technical replicates. Hellemans method takes into account the efficiency value of each primer pair. As reference Ct, we used the average Ct of all the samples for the expression of MLO genes, whereas for the analysis on other genes involved in plant defense or mlo resistance, we used the control EVB at T=0. The two different methods were selected for graphical reasons.

Statistical Analysis

Disease Severity

[0062] Severity data were analyzed using the Statistica 9 software (StatSoft, Tulsa, USA) and the statistical package SPSS(IBM, Armonk, USA). The smallest statistical unit was the whole plant. We averaged the severity values of all the leaves of the plant and used the resulting average severity for further analysis. Data with a normal distribution (Kolmogorov-Smirnov and Shapiro-Wilk tests P>0.05) were validated for variances homogeneity (Levene's test, P>0.05) and subsequently used for one-way ANOVA with Tukey's post-hoc test, to detect significant differences (P<0.05) at each time point. Data were transformed with the following equation y=arcsin(x), in order to meet the pre-requisites of the ANOVA. In case of non-homogeneous variances, the Games-Howell's post-hoc test was used.

[0063] Data from the two experiments were pooled, and the analysis carried out independently for the three time points (14, 22 and 30 dpi). AUDPC data were analyzed as described above for severity data. Data of the conidia counts were analyzed with Kruskall-Wallis test (P<0.05).

qPCR Data Analysis

[0064] For the gene expression analysis, values of relative expression were transformed in logarithmic scale according to the equation Y=ln(x) (Pessina et al., 2014) to obtain normal distribution and homogeneity of variances of the residues, assessed with the tests of Shapiro-Wilk (P<0.05) and Levene (P<0.05), respectively. Pairwise comparison of homoscedastic data was carried out with Tukey's test (P<0.05), whereas non-homoscedastic data were analyzed with Games-Howell test (P<0.05) using the statistical package SPSS(IBM).

[0065] The relative expression of MLO genes from two experiments were analyzed independently and subsequently pooled. To assess differences in expression, one-way ANOVA with Tukey post-hoc test (P<0.05) was used to detect significant differences at each time point. In addition, a two-way ANOVA with Tukey post-hoc test (P<0.05) was used on all the data, to consider at the same time the effects of the transgenic line and of the time point. We drew conclusions from this test only when there were no significant interactions (P>0.05) between the factors time point and transgenic line. For the gene expression characterization of TLB4, we used Fisher as post-hoc test.

Correlation

[0066] We used the two-tailed Pearson's correlation test to investigate two possible correlations: between disease severity and amount of conidia at 30 dpi and between disease severity at 14 dpi and relative expression of MLO genes at 10 dpi. In both cases, all data, severity and relative expression, have been transformed with the following equation y=arcsin(x), to achieve normal distribution.

Results

Transformation, Selection and Acclimation of MLO Transgenic Lines

[0067] A total of five gene transfers were carried out. Four were aimed to knock-down (KD) specific MLO genes (i=KD-VvMLO6, ii=KD-VvMLO7, iii=KD-VvMLO11, iv=KD-VvMLO13), the fifth to insert an empty vector. Thirty-four regenerated lines were obtained, with 26 of them confirmed to contain the insert (Table S3). The result of the PCR analysis of six lines is shown in Fig. S1. Twenty-six transgenic lines were propagated in vitro and tested for the silencing of MLO genes with qPCR. This was evident for three lines out of eight from gene transfer (iii) (KD-VvMLO11), and three out of nine from gene transfer (iv) (KD-VvMLO13). Gene transfers (i) (KD-VvMLO6) and (ii) (KD-VvMLO7) resulted in a small number of regenerated lines that showed no reduction of expression (Table S3). Regenerated lines were also tested for off-target silencing, showing that the RNAi fragments targeted other clade V MLO genes. Six lines with various combinations of silenced genes were selected and indicated with acronims TLB1 (Transgenic Line of Brachetto) to TLB6 (Table S3). Lines from TLB1 to 3 came from gene transfer (iii) (KD-VvMLO11), lines from TLB4 to TLB6 from gene transfer (iv) (KD-VvMLO13) (Table S3). The control was the EVB line (Empty Vector Brachetto). In addition, TLB7, a regenerated line with no reduction of expression, was also considered. All lines, including the control, will be referred in the text as "transgenic lines". Lines from TLB1 to 7 are further indicated as "RNAi lines" and from TLB1 to 6 "mlo lines".

The survival rate of plants to the acclimation process was around 85%. Under greenhouse conditions, the transgenic plants showed normal growth and no pleiotropic phenotypes.

Powdery Mildew Resistance of Transgenic Lines

[0068] PM inoculation was carried out on the seven RNAi lines (TLB1, TLB2, TLB3, TLB4, TLB5, TLB6, TLB7), and the transgenic control line EVB in two independent experiments. Three mlo lines, TLB4, TLB5 and TLB6, showed a significant reduction of E. necator infection (FIG. 1) which was greater than 60% at 30 dpi (Table 3).

TABLE-US-00003 TABLE 3 Disease reduction of seven RNAi lines. Average Number of Disease reduction %* Disease reduction plants 14 dpi 22 dpi 30 dpi (%) TLB1 8 22.8 32.3 34.3 29.8 TLB2 15 49.2 37.2 23.8 36.8 TLB3 15 17.9 14.8 2.0 11.6 TLB4 19 60.8 71.7 72.8 68.4 TLB5 14 76.7 79.1 74.0 76.6 TLB6 11 71.8 63.1 60.3 65.1 TLB7 13 -8.0.sup.# -21.5.sup.# -21.2.sup.# -16.9.sup.# *Line EVB was used as control (12 replicates) and disease reduction was calculated as (Disease severity of EVB - disease severity of the transgenic line)/disease severity of EVB .times. 100. .sup.#The negative values of TLB7 mean that the line showed higher level of infection compared to EVB

[0069] The disease reduction of TLB6 decreased with the progression of the infection (Table 3), possibly because of the secondary infections coming from nearby infected plants. TLB2, TLB3, and TLB7 showed a level of susceptibility to PM comparable to the EVB control (FIG. 1 and Table 2). The leaves in FIG. 1 showed the differences between resistant and susceptible lines. All the mlo lines showed reduction of conidia on the leaves surface at 30 dpi, and the decrease was statistically significant only for TLB4, TLB5 and TLB6. TLB4 showed a reduction of 93% of conidia, TLB5 of 95% and TLB6 of 72% compared to the EVB plants. The conidia counts and the disease severity were positively correlated (P=0.01), with a Pearson correlation coefficient of 0.578. This means that the reduction of symptoms on the leaves reflected the lower number of conidia on the resistant lines.

[0070] Line TLB4 was further characterized by histological analysis, demonstrating a reduced progression of PM infection compared to EVB plants at 3 dpi (FIG. 2). In EVB, the first conidiophores appeared at 10 dpi, and at 21 dpi they were spread all over the leaf surface (FIG. 2A). On the other hand, conidiophores were visible only at 21 dpi and in a limited number on TLB4 leaves (FIG. 2B). The formation of papilla was observed in TLB4 and EVB at 3 dpi (FIG. 3). The papilla of EVB had defined edges and it was present only in correspondence of the infection site of E. necator (FIG. 3B). Conversely, the papilla detected in TLB4 was more diffuse, bigger and formed in more than one site of infection of the fungus compared to EVB (FIG. 3D).

Expression of MLO Genes in the MLO Transgenic Lines and Correlation with Severity

[0071] Six mlo lines (TLB1, TLB2, TLB3, TLB4, TLB5, TLB6) and the control EVB were examined by gene expression analysis. Gene expression analysis of the four clade V MLO genes in the transgenic lines confirmed the off-target silencing seen in vitro and showed some variability among time points (FIG. 4). Lines TLB1, TLB2 and TLB3, all transformed with the constructe aimed to silence VvMLO11, indeed had the target gene VvMLO11 silenced. TLB1 showed also the silencing of VvMLO13 and TLB3 of VvMLO6 (Table 4).

TABLE-US-00004 TABLE 4 Relative expression.sup.# of four MLO genes VvMLO6 VvMLO7 VvMLO11 VvMLO13 TLB1 67% 72% 25%** 49%** TLB2 79% 94% 40%** 156% TLB3 71%* 93% 27%** 69% TLB4 38%** 49%** 34%** 33%** TLB5 35%** 55%** 50%** 88% TLB6 42%** 53%** 55%** 45%** .sup.#Each relative expression (RE %) value is the average of the values of three time points (0 dpi, 1 dpi, 10 dpi) in two experiments. RE % was calculated as follow: RE % = (RE of control EVB/RE of mlo line) * 100. *statistically significant difference at P = 0.05, accordint to Tukey post-hoc test. **statistically significant difference at P = 0.01, accordint to Tukey post-hoc test.

[0072] Lines TLB4, TLB5 and TLB6, coming from the transformation aimed to silence VvMLO13, showed more off-target silencing. In TLB4 and TLB6, all four clade V MLO genes were silenced, whereas In TLB5 VvMLO6, VvMLO7 and VvMLO11 were silenced (Table 4).

[0073] A statistically significant (P=0.05) positive Pearson's correlation was found between the relative expression of VvMLO7 and the severity of PM symptoms, but not for the other three MLO genes. The Pearson correlation coefficiency for VvMLO7 was 0.272, meaning that the correlation, although significant, was weak.

Gene Expression Analysis of the Mlo Line TLB4

[0074] The expression profile of 13 genes known to be modulated following PM infections was carried out on the resistant line TLB4 at three time points (FIG. 5). Line TLB4 was selected because it has all four MLO clade V genes silenced. In EVB, we observed a general up-regulation of genes, especially at 10 dpi. Instead, in the transgenic line TLB4, fewer genes were up-regulated and the intensity of up-regulation, in terms of fold-change, was limited. Moreover, three genes were down-regulated in TLB4 after inoculation, namely VvPR6 (PATHOGENESIS RELATED) at 1 dpi and VvNPF3.2 (NITRATE TRANSPORTER/PEPTIDE TRANSPORTER FAMILY) and VvALS1 (ACETOLACTATE SYNTHASE) at 10 dpi. It is noteworthy that, before the inoculation, there were no differences in expression between TLB4 and the control EVB.

DISCUSSION

[0075] Loss-of-function mutations of MLO genes reduce susceptibility to PM in barley (Buschges et al., 1997), Arabidopsis (Consonni et al., 2006), pea (Pavan et al., 2011), tomato (Bai et al., 2008), wheat (Wang et al., 2014), and pepper (Zheng et al., 2013). Because in dicots all Clade V MLO S-genes are implicated in PM susceptibility (Consonni et al., 2006; Bai et al., 2008; Feechan et al., 2008; Winterhagen et al., 2008), the aim of this work was to identify which of the clade V MLO genes of grapevine has a role in PM susceptibility, and can thus be inactivated to develop resistant genotypes. Out of 26 transgenic lines, six from gene transfers (iii) (KD-VvMLO11) and (iv) (KD-VvMLO13) supported significant gene knock-down. In the regenerated lines obtained from gene transfers (i) (KD-VvMLO6) and (ii) (KD-VvMLO7), reduction of expression was not evident. It cannot be excluded that this was due to the short RNAi fragments present in the constructs (Preuss and Pikaard, 2003). The detection of off-target silencing in five of the six mentioned lines was expected, as clade V MLO genes have high levels of sequence identity (36-60%, 46% on average; Feechan et al., 2008; Winterhagen et al., 2008). To find a balance between specificity (short RNAi fragments) and effectiveness (long RNAi fragments) is particularly difficult in gene families with high sequence similarity (Zhao et al., 2005). Since the aim was to study the effect of the knock-down of four MLO genes quite similar to each other, we opted for long RNAi fragments, so that off-target silencing was not only expected, but also desired. Knock-out and knock-down of MLO genes may induce pleiotropic phenotypes, like necrotic spot on leaves and reduced grain yield in barley (Jorgensen, 1992), slow growth in Arabidopsis (Consonni et al., 2006) and reduced plant size in pepper (Zheng et al., 2013). In grapevine, no pleiotropic phenotypes were observed under the experimental conditions adopted. Lines TLB4, 5 and 6, which showed clear resistance to PM, allowed to study the link between resistance and the expression of specific MLO genes. VvMLO11 expression was significantly reduced in susceptible and resistant mlo lines: it is concluded that its knock-down was not directly linked to grapevine susceptibility to PM. VvMLO6 was significantly silenced in the resistant lines TLB4, 5 and 6 and in the susceptible line TLB3. Like for VvMLO11, the knock-down of VvMLO6 in both susceptible and resistant lines indicates that this should not be a S-gene. Similarly to VvMLO6, VvMLO13 was knocked-down in the resistant lines TLB4 and 6, but also in the susceptible line TLB1. VvMLO7 was knocked-down only in the three resistant lines TLB4, 5 and 6; the conclusion is that VvMLO7 represents the main candidate for causing PM susceptibility in V. vinifera. The significant positive correlation between the relative expression of VvMLO7 and the disease severity in the MLO transgenic lines, stimulates the conclusion that either site directed mutagenesis or searching for natural non-functional alleles may be used in breeding programs to obtain PM resistant genotypes. It was, however, noted that VvMLO7 was always knocked-down together with other two or three MLO genes. Also in Arabidopsis the contemporary knock-out of three MLO genes is necessary to obtain complete resistance: knock-out of AtMLO2 results in a moderate level of resistance, whereas knock-out of AtMLO6 and AtMLO12, alone or combined, does not decrease the intensity of the infection. When AtMLO2 is knocked-out together with AtMLO6 or AtMLO12, the level of resistance rises, to become complete when the three genes are knocked-out together (Consonni et al., 2006). In grapevine, VvMLO7 seemed to act like AtMLO2 of Arabidopsis. Two candidates for an additive and synergistic role in PM susceptibility in grapevine are VvMLO6 and VvMLO11, since their expression was significantly reduced in all three resistant lines. In Arabidopsis, the knock-out of three MLO genes induces complete resistance (Consonni et al., 2006), a situation not observed in grapevine, in agreement with the incomplete silencing of MLO genes obtained by the RNAi approach. A complementation test, carried out in Arabidopsis mlo triple mutant, showed that VvMLO11 and VvMLO13 induce susceptibility to PM, whereas VvMLO7 has only a partial effect and VvMLO6 has no effect at all (Feechan et al., 2013b). However, single and double VvMLO11 and VvMLO13 knock-down mutants of V. vinifera obtained by RNAi, did not show significant reduction of PM penetration (Qiu et al., 2015). Accordingly, our data indicated VvMLO7 as the main S-gene of grapevine, with a putative additive effect provided by VvMLO11 and VvMLO6. The role of VvMLO6 would be particularly surprising, as it was not up-regulated during PM infection (Feechan et al., 2008; Winterhagen et al., 2008). Conversely, VvMLO13, which knock-down was expected to provide a significant effect on PM susceptibility, turned out to be ineffective. However, it should be considered that Feechan et al. (2013b) operated in a heterologous system (Arabidopsis) not reproducing with fidelity the PM infection of grapevine plants.

[0076] The precise mechanism through which the reduction of MLO genes expression ends up in resistance to PM pathogens is not completely clear. Resistance seems linked to secretory vesicles traffic (Miklis et al., 2007; Feechan et al., 2011) and to the formation of cell wall appositions called papillae (Consonni et al., 2006). These structures consists of a callose matrix enriched in proteins and autofluorogenic phenolics compounds (Vanacker et al. 2000), and their formation depends on endomembrane transport (Huckelhoven, 2014). The results shown in this paper indicate that all transgenic lines accumulate autofluorigenic materials overimposed to the papilla structure, although shape and dimensions of papillae were different in resistant and susceptible lines. It is known that the defense response based on papillae differs between resistant and susceptible genotypes in timing of formation, composition and size (Chowdhury et al., 2014; Huckelhoven, 2014; Lyngkj et al. 2000). Rapid formation of papillae in mlo resistant barley (Lyngkj et al. 2000) and increased size (Stolzenburg et al., 1984) correlate with mlo resistance. In grapevine, papilla formation is restricted to the site of infection in control plants, whereas it is diffused in the resistant line TLB4. Chowdhury et al. (2014) showed that the difference between effective and non-effective papillae is due to the higher concentration of callose, cellulose and arabinoxylan of the effective ones. This suggests that, in the case of grapevine, different types of fluorescence could reflect differences in the composition of the papillae. The MLO protein has been proposed to be a negative regulator of vesicle-associated and actin-dependent defense pathways at the site of attempted PM penetration (Panstruga, 2005). Furthermore, Miklis et al. (2007) proposed that, once MLO proteins are under the control of the fungus, actin filaments serve the purpose of supplying nutrients for the growing hyphae through vesicular transport. It is like if the pathogen is able to control the transport of material to the cell-wall, with the purpose of changing the composition of the papillae and turning them from effective to non-effective. The formation of papillae is not the only process instigated by the activity of MLO genes. To understand the effect of MLO knock-down on other genes involved in plant-pathogen interaction, the expression of 13 genes known to be differentially expressed after PM inoculation was analyzed. In the resistant line TLB4, the knock-down of MLO genes did not affect the level of expression of the 13 genes in absence of PM infection. Under E. necator infection (Guo et al., 2014), transcription factors VvWRKY19, VvWRKY48 and VvWRKY52 are up-regulated: the same genes appeared up-regulated in EVB in our experiments, but they were so at a much lower level in TLB4. VvNPF3.2, a nitrite/nitrate transporter up-regulated in grapevine infected with E. necator (Pike et al., 2014), was down-regulated in TLB4 at 10 dpi, indicating that in this line only a severe infection elicits VvNPF3.2 up-regulation. VvEDS1 (enhanced disease susceptibility) and VvPAD4 (phytoalexin deficient) are grapevine defense genes involved in the salicylic acid (SA) pathway (Gao F. et al., 2014). SA activates pathogenesis related genes and induces disease resistance (Ward et al., 1991). Both genes were up-regulated in the control line EVB at 10 dpi (VvPAD4 also at 1 dpi). This may indicate that only a heavy E. necator infection triggers the plant defense depending on SA. VvEDS1 was not up-regulated in TLB4, whereas VvPAD4 was up-regulated only at 10 dpi, like if the level of PM infection was insufficient to activate the reaction of the plant. Up-regulation in the control and no up-regulation in TLB4 was also observed for both VvPR1 and VvPR6, pathogenesis-related genes involved in plant defense and known to be up-regulated in PM infected grapevine leaves pre-treated with an SA analogue (Dufour et al., 2013). VvLOX1 encodes a lipoxygenase and is the homologous to Arabidopsis AtLOX2, that is up-regulated in plants infected with PM spores (Lorek, 2012). Surprisingly, this gene was up-regulated in TLB4 at 10 dpi, but not in EVB. A second lipoxygenase, VvLOX9, did not show in the grapevine lines considered any change in expression, despite being known to be involved in plant defense (Dufour et al., 2013). VvPEN1 (penetration) encodes for a SNARE protein homologous to Arabidopsis AtPEN1 and barley ROR2, which have important roles in PM penetration resistance (Collins et al., 2003). VvPEN1 when expressed in a heterologous system (Arabidopsis), is known to co-localize with VvMLO11 at sites of attempted PM penetration (Feechan et al., 20013b). However, infection with E. necator did not cause any change of its expression. VvALS1 is the homologous of a tomato acetolactate synthase, a key enzyme in the biosynthesis of the amino acids valine, leucine and isoluecine, and involved in mlo-mediated resistance (Gao D. et al., 2014). Silencing of SlALS1 in mlo tomato compromises its resistance, suggesting that amino acid homeostasis is an important process connected to mlo resistance (Gao D. et al., 2014). The complete lack of transcriptional change indicated that the function of this gene in grapevine does not depend on the transcript level. The knock-out of MLO genes increased susceptibility to other pathogens in barley (Jarosch et al., 1999; Kumar et al., 2001) and Arabidopsis (Consonni et al., 2006). The infection with P. viticola, an obligate biotroph fungus like E. necator, revealed that the knock-down of MLO genes did not change the susceptibility of grapevine to downy mildew, supporting the conclusion that MLOs S-genes are specific for E. necator and are not involved in the plant interaction with P. viticola.

CONCLUSIONS

[0077] The knock-down of MLO genes substantially reduces PM susceptibility of Vitis vinifera. The reduction of expression of VvMLO7 was the main factor involved in resistance, but the additive effects of VvMLO6 and VvMLO11 knock-down further contribute in reducing PM severity. Absolute resistance was not observed, as expected based on the incomplete silencing of MLO genes via RNAi. In mlo lines, no pleiotropic phenotypes were detected under greenhouse conditions. This work provides a crucial information that can be used in breeding grapevine varieties resistant to E. necator. The tagging via genome editing of the MLO genes identified in this paper, particularly of VvMLO7, should results in knock-out mutants highly resistant to PM. Alternatively, the search in V. vinifera and in wild species of non-functional MLO alleles, particularly of VvMLO7, should contribute to the creation of durable resistance.

ABBREVIATIONS

[0078] AUDPC: area under disease progress curve dpi: days post inoculation EVB: empty vector Brachetto PM: powdery mildew RE: relative expressionSA: salicylic acid

TLB1-7=Transgenic Line Brachetto 1-7

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[0121] Parlevliet J E: What is durable resistance, a general outline. In Durability of Disease Resistance. Edited by Jacobs T H, Parlevliet J E. Dordrecht: Kluwer; 1993:23-29.

[0122] Pavan S, Jacobsen E, Visser RGF, Bai Y: Loss of susceptibility as a novel breeding strategy for durable and broad-spectrum resistance. Mol Breed 2010, 25:1-12.

[0123] Pavan S, Schiavulli A, Appiano M, Marcotrigiano A R, Cillo F, Visser RGF, Bai Y, Lotti C, Ricciardi L: Pea powdery mildew er1 resistance is associated to loss-of-function mutations at a MLO homologous locus. Theor Appl Gen 2011, 123:1425-1431

[0124] Pessina S, Pavan S, Catalano D, Gallotta A, Visser RGF, Bai Y, Malnoy M, Schouten H J: Characterization of the MLO gene family in Rosaceae and gene expression analysis in Malus domestica. BMC genomics 2014, 15:618

[0125] Piffanelli P, Zhou F S, Casais C, Orme J, Jarosch B, Schaffrath U, Collins N C, Panstruga R, Schulze-Lefert

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Sequence CWU 1

1

551539PRTVitis vinifera 1Met Ala Asp Glu Leu Glu Glu Arg Ser Leu Glu Glu Thr Pro Thr Trp 1 5 10 15 Ala Val Ala Val Val Cys Phe Val Leu Leu Ala Val Ser Ile Phe Ile 20 25 30 Glu His Ile Phe His Leu Ile Gly Ser Trp Leu Lys Gly Arg His Arg 35 40 45 Arg Ala Leu Tyr Glu Ser Leu Glu Lys Ile Lys Ala Glu Leu Met Leu 50 55 60 Leu Gly Val Ile Ser Leu Leu Leu Thr Ile Leu Gln Asp Tyr Ile Ser 65 70 75 80 Lys Ile Cys Ile Ser Glu Ser Val Gly Ser Thr Trp His Pro Cys Lys 85 90 95 Lys Glu Thr Lys Asp Phe Lys Asn Thr Cys Ser Glu Gly Lys Val Pro 100 105 110 Leu Val Ser Ser Tyr Gly Ile His Gln Leu His Ile Phe Ile Phe Val 115 120 125 Leu Ala Leu Phe His Val Ile Tyr Cys Val Ala Thr Leu Ala Leu Gly 130 135 140 Arg Thr Lys Met Arg Arg Trp Lys Ala Trp Glu Asp Gln Thr Lys Thr 145 150 155 160 Ile Glu Tyr Gln Tyr Ser His Asp Pro Glu Arg Phe Arg Phe Ala Arg 165 170 175 Asp Thr Ser Phe Gly Arg Arg His Leu Asn Phe Trp Ser Arg Ser Pro 180 185 190 Val Leu Leu Trp Ile Val Cys Phe Phe Arg Gln Phe Phe Arg Ser Val 195 200 205 Asn Asn Val Asp Tyr Leu Thr Leu Arg His Gly Phe Ile Met Ala His 210 215 220 Leu Ser Pro Gly Ser Glu Thr Lys Phe Asp Phe Arg Asn Tyr Ile Lys 225 230 235 240 Arg Ser Leu Glu Glu Asp Phe Lys Val Val Val Ser Ile Ser Pro Val 245 250 255 Ile Trp Phe Cys Ala Val Leu Phe Leu Leu Thr Asn Thr His Gly Trp 260 265 270 Tyr Ser Tyr Leu Trp Leu Pro Phe Ile Pro Leu Val Ile Ile Leu Leu 275 280 285 Val Gly Thr Lys Leu Gln Val Ile Ile Thr Lys Leu Gly Leu Arg Ile 290 295 300 Ala Glu Arg Gly Asp Val Val Lys Gly Thr Pro Val Val Glu Pro Ala 305 310 315 320 Asn Asp Leu Phe Trp Phe Asn Arg Pro His Leu Ile Leu Phe Leu Ile 325 330 335 Asn Phe Val Leu Phe Leu Asn Ala Phe Gln Leu Ala Phe Phe Ala Trp 340 345 350 Ser Thr Tyr Glu Phe Gly Leu Gln Ser Cys Tyr His Gln Lys Thr Glu 355 360 365 Asp Ile Ala Ile Arg Ile Ser Met Gly Val Ile Thr Gln Val Leu Cys 370 375 380 Ser Tyr Val Thr Leu Pro Leu Tyr Ala Leu Val Thr Gln Met Gly Ser 385 390 395 400 Thr Met Arg Pro Thr Ile Phe Asn Glu Arg Val Ala Thr Ala Leu Arg 405 410 415 Ser Trp His Gln Ala Ala Arg Lys His Thr Lys His Gly Arg His Ser 420 425 430 Asn Gly Val Ser Pro Gln Ser Ser Arg Pro Ala Thr Pro Ser Tyr Gly 435 440 445 Met Ser Pro Val His Leu Leu Gln Gly Tyr His Asn His Thr Pro Asp 450 455 460 Met Ser Pro Arg Arg Ser Asn Leu Asp Asn Glu Trp Tyr Gly Glu Gly 465 470 475 480 Ala Gly Ser Pro Gly Lys Lys Asp Asp Asp Glu His Glu Lys Glu Lys 485 490 495 Phe Glu Ser Arg Glu Gln Gly Gln Gly Ile Gly Asp Ser Ser Ser Thr 500 505 510 Gln Leu Pro Leu Gly Pro Arg Pro Ile Arg Thr Gln His Glu Ile Asn 515 520 525 Ile Thr Leu Ser Asp Phe Ser Phe Ala Lys Arg 530 535 2583PRTVitis vinifera 2Met Ala Lys Gly Ser Lys Asp Arg Ser Leu Glu Gln Thr Pro Thr Trp 1 5 10 15 Ala Val Ala Val Val Cys Phe Val Leu Val Leu Ile Ser Ile Ile Ile 20 25 30 Glu Tyr Ile Leu His Leu Ile Gly Lys Trp Leu Thr Lys Arg Asn Lys 35 40 45 Arg Ala Leu Tyr Glu Ala Leu Glu Lys Ile Lys Ser Glu Leu Met Leu 50 55 60 Leu Gly Phe Ile Ser Leu Leu Leu Thr Val Gly Gln Gly Thr Ile Ala 65 70 75 80 Gly Ile Cys Ile Ser Glu Lys Ile Ala Ala Thr Trp His Pro Cys Gly 85 90 95 Lys Lys Gln Glu Ile Lys Tyr Val Ser Asn Glu Glu Asp Tyr Gly Lys 100 105 110 Arg Arg Leu Leu Glu Ile Ser Asp Ser Asp Gly Ser Asn Arg Arg Val 115 120 125 Leu Ala Ala Ala Gly Asp Asp Lys Cys Gly Glu Gly Lys Val Pro Phe 130 135 140 Val Ser Asn Tyr Gly Ile His Gln Leu His Ile Phe Ile Phe Val Leu 145 150 155 160 Ala Val Phe His Val Leu Tyr Cys Ile Ile Thr Leu Ala Leu Gly Arg 165 170 175 Ala Lys Met Arg Lys Trp Lys Ala Trp Glu Met Glu Thr Arg Thr Ala 180 185 190 Glu Tyr Arg Phe Ala Asn Asp Pro Glu Arg Phe Arg Phe Ala Arg Asp 195 200 205 Thr Ser Phe Gly Arg Arg His Leu His Ser Trp Ser Thr Ser Pro Val 210 215 220 Leu Leu Trp Ile Val Cys Phe Phe Arg Gln Phe Val Arg Ser Val Pro 225 230 235 240 Lys Val Asp Tyr Leu Thr Leu Arg His Gly Phe Ile Ile Ala His Leu 245 250 255 Ala Pro Glu Ser His Thr Arg Phe Asp Phe Gln Lys Tyr Ile Lys Arg 260 265 270 Ser Leu Glu Glu Asp Phe Lys Val Val Val Gly Ile Ser Pro Ile Ile 275 280 285 Trp Phe Cys Ala Val Leu Phe Leu Leu Phe Asn Thr His Gly Trp His 290 295 300 Ser Tyr Leu Trp Leu Pro Phe Ile Pro Leu Ile Ile Ile Leu Met Val 305 310 315 320 Gly Thr Lys Leu Gln Val Ile Ile Thr Lys Met Gly Leu Arg Ile Gln 325 330 335 Glu Arg Gly Glu Val Val Lys Gly Thr Pro Val Val Glu Pro Gly Asp 340 345 350 Asp Leu Phe Trp Phe Asn Gln Pro Arg Leu Ile Leu Tyr Leu Ile Asn 355 360 365 Phe Val Leu Phe Gln Asn Ala Phe Gln Val Ala Phe Phe Ala Trp Thr 370 375 380 Trp Tyr Glu Phe Gly Leu Lys Ser Cys Phe His Glu Arg Ile Glu Asp 385 390 395 400 Val Val Ile Arg Ile Ser Met Gly Val Ile Val Gln Ile Leu Cys Ser 405 410 415 Tyr Val Thr Leu Pro Leu Tyr Ala Leu Val Thr Gln Met Gly Ser Thr 420 425 430 Met Lys Pro Thr Ile Phe Asn Asp Arg Val Ala Lys Ala Leu Arg Asn 435 440 445 Trp His His Ala Ala Arg Lys His Ile Lys Gln Ser Lys Gln Ser Ser 450 455 460 Ala Val Thr Pro Val Ser Ser Arg Ala Gly Thr Pro Phe Ser Ser Arg 465 470 475 480 Pro Gly Thr Pro Leu His Gly Met Ser Pro Val His Leu Leu Arg His 485 490 495 His Arg Ser Glu Leu Asp Ser Val Gln Thr Ser Pro Arg Met Ser Asn 500 505 510 Phe Asp Asn Glu Gly Pro Glu Thr Asp Glu Tyr Arg His Arg Glu Asp 515 520 525 Ile Ser Trp Ser Glu His His Arg Asn Pro Gly Pro Glu Glu Glu Gly 530 535 540 Arg Asp Thr Asn His Arg Ile Leu Thr Arg Thr Met Pro Ala Pro Gln 545 550 555 560 Ala Asp Asn Ala Gln His Glu Ile Asp Ile Gln Pro Met Asp Phe Ser 565 570 575 Phe Asp Lys Arg Ala Arg Thr 580 3553PRTVitis vinifera 3Met Ala Ala Gly Asp Gly Val Ser Arg Ser Leu Gln Glu Thr Pro Ser 1 5 10 15 Trp Ala Leu Ala Thr Val Cys Phe Ile Phe Ile Ser Leu Ser Ile Phe 20 25 30 Ile Glu His Leu Ile His Leu Leu Ala Asn Trp Leu Arg Arg His Lys 35 40 45 Lys Thr Ala Leu Leu Glu Ala Val Glu Lys Leu Lys Ser Val Leu Met 50 55 60 Leu Leu Gly Phe Met Ser Leu Ile Leu Ala Val Thr Gln Lys Phe Ile 65 70 75 80 Ser Lys Ile Cys Ile Pro Asn Asn Ala Ala Tyr Thr Met Leu Pro Cys 85 90 95 Arg Lys Ile Ile Lys Ile Lys Thr Thr Lys Ala Leu Gly His Met Gln 100 105 110 Ile Trp Thr His Thr Phe Gln Asn Trp Leu Ser Ser Glu Ser Ser Val 115 120 125 Ser Gln Glu Arg Arg Ser Ala Ala Gln Ser Ser Glu Ser Ser Asp Tyr 130 135 140 Cys Ser Ser Lys Asp Met Thr Ser Leu Ile Ser Pro Glu Gly Met Asn 145 150 155 160 Gln Leu Ser Ile Phe Ile Phe Val Leu Ala Val Met Gln Ile Val Tyr 165 170 175 Ser Val Leu Thr Met Ala Leu Gly Arg Ala Lys Met Arg Arg Trp Lys 180 185 190 Ala Trp Glu Lys Glu Thr Gln Thr Ile Glu Tyr Gln Ala Ala Asn Asp 195 200 205 Pro Asn Arg Phe Arg Tyr Thr Arg Gln Thr Thr Phe Gly Arg Arg His 210 215 220 Met Thr Asn Cys Thr Glu Thr Pro Leu His Leu Trp Thr Lys Cys Phe 225 230 235 240 Phe Arg Gln Phe Phe His Ser Val Ala Lys Val Asp Tyr Leu Thr Leu 245 250 255 Arg His Gly Phe Ile Ala Ala His Leu Ser Ile Asn Asn Lys Thr Phe 260 265 270 Asn Phe Gln Lys Tyr Ile Gln Arg Ser Leu Glu Asp Asp Phe Lys Val 275 280 285 Val Val Gly Ile Ser Pro Val Met Trp Phe Ile Val Val Ile Phe Ile 290 295 300 Leu Leu Asp Val His Gly Trp His Ala Tyr Leu Ser Leu Ser Phe Leu 305 310 315 320 Pro Leu Leu Ile Val Leu Val Leu Gly Thr Lys Leu Glu Val Ile Val 325 330 335 Ala Arg Met Ala Leu Lys Leu Lys Asp Lys Asn Ser Thr Ile Lys Gly 340 345 350 Thr Pro Leu Val Gln Pro Asn Asp Asp Leu Phe Trp Phe Ser His Pro 355 360 365 Lys Phe Val Leu Thr Leu Leu His Leu Thr Leu Phe Met Asn Ala Phe 370 375 380 Glu Leu Ala Phe Phe Val Trp Val Thr Leu Thr Phe Gly Leu Lys Ser 385 390 395 400 Cys Tyr His Glu Arg Ile Glu Thr Ile Ile Ile Arg Val Val Leu Ala 405 410 415 Val Thr Val Gln Val Leu Cys Ser Tyr Ile Thr Leu Pro Leu Tyr Ala 420 425 430 Leu Val Thr Gln Met Gly Thr Asn Phe Lys Ser Ala Val Leu Glu Glu 435 440 445 Gln Thr Ala Asn Val Ile Arg Gln Trp His Ala Thr Val Lys Gln Lys 450 455 460 Arg Lys Lys Gln Lys Asp His Ser Gln Ser Leu His Asp Tyr Ser Thr 465 470 475 480 Thr Thr Trp Gly Ser Ser Arg Thr Ser Pro His Asp Leu Ser Pro His 485 490 495 Arg Arg Ser Pro Asn Phe Ser Thr Glu Ile Thr Ala Ile Gly Thr Glu 500 505 510 Ser Glu Ile Ile Pro Asp His Gln Gln Glu Ile Val Val Gln Asp Glu 515 520 525 His Thr Pro Ala Asp His Thr Val Ser Ser Ile Ala Val Gln Ile Glu 530 535 540 Met Pro Glu Ile Ser Ile Ser Arg Thr 545 550 41620DNAVitis vinifera 4atggctgatg aacttgaaga gcgtagtttg gaggaaacgc ctacttgggc tgttgcagtg 60gtctgctttg tgttgcttgc tgtttcgatc ttcatcgaac atatttttca tcttattgga 120tcgtggttaa aaggcagaca caggcgagcc ctttatgaat ctctggaaaa gatcaaagca 180gagcttatgc tgttgggagt catatccttg ctgcttacaa tattacaaga ttacatttca 240aagatatgca tttctgagag tgttgggtcc acttggcacc cttgtaaaaa ggaaaccaaa 300gattttaaga acacatgctc tgagggaaaa gtcccattag tgtcttccta tgggatccat 360caactccata tattcatctt tgtgttagct ctctttcatg tgatttactg tgtggccacc 420ttggctttgg gaagaaccaa gatgagaaga tggaaggctt gggaggatca aactaagacg 480attgaatatc aatactctca tgatccagag aggtttaggt ttgcaaggga tacatccttt 540gggcgcaggc atttgaattt ctggagccgc tctcctgttc tcctctggat tgtctgcttc 600ttcagacaat tcttcagatc ggttaacaac gttgactatc ttacattaag acatggattt 660atcatggcac atttgtcacc tggaagtgaa acaaaatttg atttccgaaa ttacatcaaa 720agatcgcttg aagaggactt caaagttgta gtgagcatca gcccagtaat atggttctgt 780gcagtattgt tcctactcac caacacacat gggtggtatt cttacttgtg gcttccattc 840atccccttag ttataatact cttggtggga acaaagcttc aagtgatcat aaccaaactg 900ggattgagga ttgcagagag aggtgatgtg gtgaagggta caccagtagt tgagccagcc 960aacgacctct tctggttcaa tcgccctcac ctcatcctct ttctgatcaa ctttgttctc 1020ttcctgaatg catttcagct ggctttcttc gcatggagca cgtatgagtt tgggctgcaa 1080tcttgctatc accaaaagac agaagacatt gccatcagaa tctcaatggg ggtcatcaca 1140caggtactat gcagttatgt gacactccca ctctatgcct tggtgacaca gatgggctcc 1200accatgagac cgacaatttt taacgagaga gtggccacgg ctctaagaag ctggcaccag 1260gcggccagga agcacacaaa acatgggcgc cactcgaatg gtgtgtcccc acagtcgagt 1320aggccagcga ctccatcata tgggatgtcc cctgttcatc tattgcaagg ctaccacaac 1380cacactcctg atatgtctcc aagacgatca aacttggaca acgaatggta tggggaagga 1440gcagggtctc cagggaagaa ggatgatgat gagcatgaaa aggagaaatt tgaatccaga 1500gagcagggac aagggattgg agactcgagc tcaacccaac tgccccttgg accccgccca 1560atccgaaccc aacatgagat caacattact ttatcggatt tctcatttgc aaagcgctga 162051695DNAVitis vinifera 5atggctaagg gatcaaagga tcgatctttg gagcaaacac cgacttgggc ggttgcagtg 60gtctgttttg tgctggtttt gatatcaatt atcatcgaat acatccttca cttaattgga 120aagtggctaa caaagagaaa caaacgagct ctttatgaag cacttgaaaa gattaagtca 180cttatgctac tggggttcat atcgctgctc ctaacggtag gacaaggaac tattgcggga 240atatgcatat cagagaagat tgcagcaacc tggcacccat gtgggaagaa acaagaaatc 300aagtatgttt ctaatgaaga agattatggc aagagaaggc ttcttgaaat ttcagattcc 360gatggaagta atcgacgtgt gttagcggcc gcgggagatg acaaatgtgg agagggtaaa 420gtcccgtttg tctccaatta tgggatccac caacttcaca tattcatctt cgttcttgct 480gttttccaca tgaggaagtg gaaggcgtgg gaaatggaaa caagaacagc cgagtaccgg 540ttcgcaaacc cagagagatt taggtttgca agagacacct catttgggag aaggcatttg 600cactcctgga gcacctcccc agttctcctt tggattgtgt gtttcttcag acaatttgtc 660agatcagttc ccaaagttga ttacttgacc ttgcgccatg ggtttatcat tgcacatttg 720gcacccgaga gtcatactag atttgatttc cagaaataca tcaagagatc actcgaggag 780gatttcaaag ttgtagtcgg tatcccaata atctggttct gtgctgtact cttcctacta 840ttcaacaccc attggcattc ttatctatgg ttacccttta tcccactaat tatcatcctg 900atggtgggga caaaactaca agttatcata acaaagatgg ggctgagaat acaggagaga 960ggagaggtgg taaaaggaac cccagtggtg gagcctggtg atgatctttt ctggttcaac 1020cagccacgtc tcattctcta cctgattaac tttgttctct ttcagaacgc attccaggtt 1080gccttctttg catggacctg gtatgagttt ggcttgaaat cttgtttcca cgaaaggata 1140gaagatgtgg tcatccgcat atcaatggtc atagtacaaa tactctgcag ctatgtgact 1200cttcctctgt atgccttggt tacacagatg ggatctacca tgaagcccac catcttcaat 1260gacagagtgg cgaaagctct gagaaactgg caccacgctg caaggaagca cataaaacag 1320agcaagcaat caagcgctgt gacccctgta tcaagtaggg caggcactcc cttttcaagt 1380aggccaggca cccccttaca tggcatgtcc cctgttcatc tactccgcca ccaccgcagt 1440gagctcgaca gtgttcaaac atctcctaga atgtccaatt ttgacaatga aggtccggag 1500acagacgagt atcgccaccg tgaggatata tcatggtcwg aacatcatag aaatcctggt 1560ccagaagaag aggggaggga cacaaatcat aggatcttga cccgtaccat gccagctcct 1620caagctgaca atgctcagca cgaaattgac attcagccca tggacttttc attcgataaa 1680agagcaagaa cttga 169561792DNAVitis vinifera 6ccatggctga tgaacttgaa gatcgtagtt tgacggaaac gcctacttgg gctgttgcag 60tggtctgttt tgtgttgctt gctgtttcga tcttcatcga acatattatt catcatattg 120gatcgtggtt agcaagaaga aacaagcgag ccctttatga agctctggaa aagatcaaag 180cagagcttat gctgttggga ttcatgtcct tgctgcttac agtattacaa actcccattt 240caaagatatg catttctaag agtgttggat ccacttggta cccttgtgat gttgatgaga 300aagaatttaa aaacacatgc ggcactgaat caggaaaagt cccatttgtg tcttactatg 360ggatccatca gctccatata tttatctttg tgctagctct ctttcatgtg atctactgcg 420tggccacctt ggctttggga acatacaaga tgagaagatg gaagacttgg gaggatgaaa 480ctaggacagc tgaatatcaa tactctcatg atccagagag gtttaggtat gcaagggaaa 540catcctttgg gcgcaggcat ttgaatttct ggagcagctc tcctgttctc ctatggattg 600tgtgcttctt tagacaattc tacggatcgg ttcacagaga tgactatctt gctttaagac

660atggatttat cgtggcacat ttggcacccg aaagcgaaag aaaatttgat ttccggaagt 720acatccacag atcacttgaa gaggacttca aagctgtagt gggcatcagc ccagtaatat 780ggttctgtgc aatattgttc ctactcacca acacacatgg gtggtattct tacttttggc 840ttccattcat ccccttaatt atactgctct tggtgggaac aaagctacaa gtgataataa 900ccgaattggg attgaggatt gcagagagag gtgttgtggt gaagggtaca ccaatagttg 960aaccaggcga ccacctcttt tggttcaatc gccccagcct catgctcttt ctgatcaact 1020tcgttctctt tctgaatgca tttcagctgg ctttctttgc atggagcacg tatgggttga 1080aatcttgcta tcatgacact actgaagatt atgtcatcag aatcacaatg ggggtcatga 1140cacaggtact gtgcagttat gtgacactcc cactctatgc cttagtgaca cagatgggca 1200ccaccatgag atcgactgtt tttaatgaca aagtagccgt ggctctaaga gactggcacg 1260agacggccag aaagcacact agacacgggc actcggatgg tgtgtcccca cagtcaagta 1320ggccatcgac cccatcatat gggatgtccc cagttcatct gttgcaaagc tacgacaaca 1380acactcctga tatgtctcca gtggcatcaa actacgacaa cgaacggtgg tatggagaag 1440gatcagggtc tctagggaag aaggatgatg atgagcaaag gccagagaat tttgaatcga 1500gagagccggg acgagggact caagactcaa gctcagccca attggccctg ggacccctcc 1560ccattcaaac tcaacatgag gtcaacatca cttcatcaga gttctcattt cgtaggagcc 1620caaggagccc aaggccatga cttcgatgat gcgaaggatg attaattgag gacaaaactc 1680cgcgtattga tttggtattt tgtttttcgt ttctgcagtt tgtattttgc atgtacattt 1740gttacccttg taattcgatc aatttatgtt tcttcaaaaa aaaaaaaaaa aa 1792720DNAArtificial SequenceEF1alpha forward primer 7gaactgggtg cttgataggc 20824DNAArtificial SequenceEF1alpha reverse primer 8aaccaaaata tccggagtaa aaga 24921DNAArtificial SequenceGAPDH forward primer 9ttctcgttga gggctattcc a 211021DNAArtificial SequenceGAPDH reverse primer 10ccacagactt catcggtgac a 211121DNAArtificial SequenceActin forward primer 11tccttgcctt gcgtcatcta t 211223DNAArtificial SequenceActin reverse primer 12caccaatcac tctcctgcta caa 231321DNAArtificial SequenceVvMLO6 forward primer 13gtgcagttat gtgacactcc c 211417DNAArtificial SequenceVvMLO6 reverse primer 14acacaccatc cgagtgc 171520DNAArtificial SequenceVvMLO7 forward primer 15ctttcttcgc atggagcacg 201620DNAArtificial SequenceVvMLO7 reverse primer 16gagcccatct gtgtcaccaa 201717DNAArtificial SequenceVvMLO11 forward primer 17gcaccccctt acatggc 171823DNAArtificial SequenceVvMLO11 reverse primer 18tctggaccag gatttctatg atg 231920DNAArtificial SequenceVvMLO13 forward primer 19ctggtgacac agatgggttc 202020DNAArtificial SequenceVvMLO13 reverse primer 20ctacttgaca tgggtgtggc 202120DNAArtificial SequenceVvWRKY19 forward primer 21ggggaggctg tggttaggtt 202220DNAArtificial SequenceVvWRKY19 reverse primer 22gtttggcatt tggcttgtct 202322DNAArtificial SequenceVvWRKY27 forward primer 23cttggatcag aatcacccct aa 222421DNAArtificial SequenceVvWRKY27 reverse primer 24gccgtggtat gtggttttgt a 212522DNAArtificial SequenceVvWRKY48 forward primer 25caagatttca aggaccaagc ag 222621DNAArtificial SequenceVvWRKY48 reverse primer 26agtatgcctt cctcggtatg t 212722DNAArtificial SequenceVvWRKY52 forward primer 27cctcttgatg atgggtttag tt 222821DNAArtificial SequenceVvWRKY52 reverse primer 28gtcttccacg gtaggtgatt t 212926DNAArtificial SequenceVvEDS1 forward primer 29agggttttat attgttatct caaggc 263033DNAArtificial SequenceVvEDS1 reverse primer 30ggaagaaaat atcttattac tacataatgt ttc 333120DNAArtificial SequenceVvLOX9 forward primer 31gacaagaagg acgagccttg 203220DNAArtificial SequenceVvLOX9 reverse primer 32cataagggta ctgcccgaaa 203320DNAArtificial SequenceVvLOX1 forward primer 33atcaatgctc ttgctcggga 203420DNAArtificial SequenceVvLOX1 reverse primer 34ccagagctgg tcataggcag 203520DNAArtificial SequenceVvPAD4 forward primer 35acgattgcac tggtaagcca 203620DNAArtificial SequenceVvPAD4 reverse primer 36cgactccgtc atcgcctaaa 203720DNAArtificial SequenceVvPEN1 forward primer 37cttcgcaaga agctcaggga 203820DNAArtificial SequenceVvPEN1 reverse primer 38tgctcttgga tcgccttctg 203920DNAArtificial SequenceVvPR1 forward primer 39cccagaactc tccacaggac 204020DNAArtificial SequenceVvPR1 reverse primer 40gcagctacag tgtcgttcca 204120DNAArtificial SequenceVvPR6 forward primer 41acgaaaacgg catcgtaatc 204220DNAArtificial SequenceVvPR6 reverse primer 42tcttactggg gcaccatttc 204320DNAArtificial SequenceVvNPF3.2 forward primer 43tcgtcacatc agcacagctt 204420DNAArtificial SequenceVvNPF3.2 reverse primer 44atctgcgagc caatggaaca 204520DNAArtificial Sequence35S promoter 45cgcacaatcc cactatcctt 204627DNAArtificial SequenceVvMLO6 forward primer 46cacctgctta cagtattaca aactccc 274720DNAArtificial SequenceVvMLO6 reverse primer 47tttcccttgc atacctaaac 204825DNAArtificial SequenceVvMLO7 forward primer 48caccgacaat ttttaacgag agagt 254921DNAArtificial SequenceVvMLO7 reverse primer 49atctcatgtt gggttcggat t 215024DNAArtificial SequenceVvMLO11 forward primer 50cacctcactt atgctactgg ggtt 245124DNAArtificial SequenceVvMLO11 reverse primer 51atcaactttg ggaactgatc tgac 245224DNAArtificial SequenceVvMLO13 forward primer 52caccgagcta atgttgctag ggtt 245320DNAArtificial SequenceVvMLO13 reverse primer 53aaattttgca tggctttgag 205420DNAArtificial SequenceVvALS1 forward primer 54ccgtgcatac cgagcatttg 205520DNAArtificial SequenceVvALS1 reverse primer 55aggccggttc tgtatgttgg 20

Claims

1-21. (canceled)

22. An isolated Vitis vinifera having resistance to powdery mildew and comprising in its genome a modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions, wherein the modified gene results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 1 compared to a Vitis vinifera lacking said modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 4 compared to a Vitis vinifera lacking said modified gene.

23. The isolated Vitis vinifera of claim 22, wherein the resistance to powdery mildew is resistance to powdery mildew caused by Erysiphe necator.

24. The isolated Vitis vinifera of claim 22, wherein the modified gene results in at least a 10% reduction in expression of the protein having the amino acid sequence of SEQ ID NO: 1 compared to a Vitis vinifera lacking said modified gene or at least a 10% reduction in amount of mRNA having the nucleotide sequence of SEQ ID NO: 4 compared to a Vitis vinifera lacking said modified gene.

25. The isolated Vitis vinifera of claim 22, further comprising in its genome a second modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions, wherein the modified second gene results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 2 compared to a Vitis vinifera lacking said second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 5 compared to a Vitis vinifera lacking said second modified gene.

26. The isolated Vitis vinifera of claim 22, further comprising in its genome a second modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions, wherein the modified second gene results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 3 compared to a Vitis vinifera lacking said second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 6 compared to a Vitis vinifera lacking said second modified gene.

27. The isolated Vitis vinifera of claim 22, further comprising in its genome second and third modified genes comprising one or more non-natural mutations, insertions, substitutions, or deletions, wherein the modified second gene results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 2 compared to a Vitis vinifera lacking said second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 5 compared to a Vitis vinifera lacking said modified gene; and wherein the modified third gene results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 3 compared to a Vitis vinifera lacking said third modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 6 compared to a Vitis vinifera lacking said third modified gene.

28. A seed, fruit, plant part, or propagation material of the isolated Vitis vinifera of claim 22, wherein the seed, fruit, plant part, or propagation material comprises the modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions resulting in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 1 compared to a Vitis vinifera lacking said modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 4 compared to a Vitis vinifera lacking said modified gene.

29. A seed, fruit, plant part, or propagation material of the isolated Vitis vinifera of claim 25, wherein the seed, fruit, plant part, or propagation material comprises the modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions resulting in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 1 compared to a Vitis vinifera lacking said modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 4 compared to a Vitis vinifera lacking said modified gene, and wherein the seed, fruit, plant part, or propagation material comprises the second modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions resulting in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 2 compared to a Vitis vinifera lacking said second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 5 compared to a Vitis vinifera lacking said second modified gene.

30. A seed, fruit, plant part, or propagation material of the isolated Vitis vinifera of claim 26, wherein the seed, fruit, plant part, or propagation material comprises the modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions resulting in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 1, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 4 compared to a Vitis vinifera lacking said modified gene, and wherein the seed, fruit, plant part, or propagation material comprises the second modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions resulting in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 3 compared to a Vitis vinifera lacking said second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 6 compared to a Vitis vinifera lacking said second modified gene.

31. A seed, fruit, plant part, or propagation material of the isolated Vitis vinifera of claim 27, wherein the seed, fruit, plant part, or propagation material comprises the three modified genes comprising one or more non-natural mutations, insertions, substitutions, or deletions resulting in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 1 compared to a Vitis vinifera lacking said modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 4 compared to a Vitis vinifera lacking said modified gene, and wherein the seed, fruit, plant part, or propagation material comprises the second modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions resulting in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 2 compared to a Vitis vinifera lacking said second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 5 compared to a Vitis vinifera lacking said second modified gene, and wherein the seed, fruit, plant part, or propagation material comprises the third modified gene comprising one or more non-natural mutations, insertions, substitutions, or deletions resulting in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 3 compared to a Vitis vinifera lacking said third modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 6 compared to a Vitis vinifera lacking said third modified gene.

32. A method for obtaining a Vitis vinifera having resistance to powdery mildew comprising introducing a modification comprising one or snore non-natural mutations, insertions, substitutions, or deletions to a gene encoding a protein having the amino acid sequence of SEQ ID NO: 1 in a Vitis vinifera, wherein the modification results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 1 compared to a Vitis vinifera lacking the modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 4 compared to a Vitis vinifera lacking said modified gene.

33. The method of claim 32, wherein the resistance to powdery mildew is resistance to powdery mildew caused by Erysiphe necator.

34. The method of claim 32, wherein the modified gene results in at least a 10% reduction in expression of the protein having the amino acid sequence of SEQ ID NO: 1 compared to a Vitis vinifera lacking said modified gene or at least a 10% reduction in amount of mRNA having the nucleotide sequence of SEQ ID NO: 4 compared to a Vitis vinifera lacking said modified gene.

35. The method of claim 32, wherein the method further comprises introducing a second modification comprising one or more non-natural mutations, insertions, substitutions, or deletions to a second gene encoding a protein having the amino acid sequence of SEQ ID NO: 2 in a Vitis vinifera, wherein the modification results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 2 compared to a Vitis vinifera lacking the second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 5 compared to a Vitis vinifera lacking the second modified gene.

36. The method of claim 32, wherein the method further comprises introducing a second modification comprising one or more non-natural mutations, insertions, substitutions, or deletions to a second gene encoding a protein having the amino acid sequence of SEQ ID NO: 3 in a Vitis vinifera, wherein the modification results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 3 compared to a Vitis vinifera lacking the second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 6 compared to a Vitis vinifera lacking the second modified gene.

37. The method of claim 32, wherein the method further comprises: introducing a second modification comprising one or more non-natural mutations, insertions, substitutions, or deletions to a second gene encoding a protein having the amino acid sequence of SEQ ID NO: 2 in a Vitis vinifera, wherein the modification results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 2 compared to a Vitis vinifera lacking the second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 5 compared to a Vitis vinifera lacking the second modified gene; and introducing a third modification comprising one or more non-natural mutations, insertions, substitutions, or deletions to a third gene encoding a protein having the amino acid sequence of SEQ ID NO: 3 in a Vitis vinifera, wherein the modification results in: a decrease of function, loss of function, reduced expression, or absence of a protein having the amino acid sequence of SEQ ID NO: 3 compared to a Vitis vinifera lacking the second modified gene, or a decrease in mRNA having the nucleotide sequence of SEQ ID NO: 6 compared to a Vitis vinifera lacking the second modified gene.