Progress 04/01/08 to 03/31/13
Outputs
Progress Report Objectives (from AD-416): 1. Develop improved genetic systems for functional genomics research of grape pest and disease resistance. 2. Characterize the genetic, genomic, proteomic, and other aspects of the interaction of grapevines and fungal and oomycete pathogens to identify the key determinants of resistance, tolerance, and susceptibility. 3. Improve grapevine rootstocks through identification, development, deployment, and enhancement of resistance to pests and diseases. Approach (from AD-416): Develop a grapevine system with reduced juvenile period for rapid candidate gene evaluation of disease and pest resistance. Optimize and evaluate the utility of a newly created dwarf grapevine system for investigating interactions between grapevines and key pests and pathogens. Determine race-specificity of powdery mildew resistance in Vitis species. Develop molecular markers associated with resistance to grape powdery mildew. Characterize the relationship between biochemical changes in the berry-powdery mildew interface and developmentally- regulated resistance to powdery mildew on grape berries. Enhance non- race-specific resistance in Vitis vinifera to powdery mildew and/or downy mildew via knock-out of susceptibility loci. Characterize the genetic control of resistance to Meloidogyne species (root-knot nematodes) in grapevine. Develop molecular markers associated with resistance to root- knot nematodes. Develop grape rootstocks with enhanced resistance to root-knot nematodes. Evaluate the ability of rootstocks to mitigate symptoms of Pierce�s disease in grapevine rootstocks. Develop autotetraploid selections with reduced vigor induction and evaluate their pest resistance. This project terminated on March 31st, 2013. A new OSQR Project (1910- 21220-006-00D) was approved for implementation on April 1, 2013. In order to develop a small, easily transformed grapevine variety for grape functional genomics research, we evaluated the impact of allelic forms of the grape GAI gene on plant growth and development in transgenic Arabidopsis and grapes. We observed that different grape GAI gene allelic forms have different impacts on plant growth, architecture and flowering time. Results from this work will advance our understanding of grape GAI gene function and help create a new variety suited for grape functional genomics research. The results will also help develop desirable vine architecture for enhancing grape yield and fruit quality as well as vine suitability for mechanical pruning and harvest. We have also developed a transgenic hairy root system as well as a stable transgenic platform for grapevine functional genomics studies. In protecting grapes from fungal and oomycete pathogens, we pursued a strategy to know the enemy then identify tools effective against that enemy. We discovered that powdery mildew (PM) has maximal genetic diversity in the Eastern U.S. We developed molecular technologies to track variants of PM to predict which disease management tools should be most effective. Most grape varieties are susceptible to PM and require frequent fungicide applications. We developed collaborations with all US public grape breeders and made significant progress advancing 6 sources of PM resistance into grape breeding lines. In addition, we applied DNA markers linked with four PM resistance genes to help grape breeders predict PM resistance. Furthermore, we observed that PM clones are differential in their ability to grow on resistant vines. We identified and silenced four grape susceptibility genes in �Chardonnay� and showed that these vines were more resistant to PM. These discoveries will reduce PM and inputs required for PM control. Root-knot nematodes are a major pest of vineyards across California and the United States. We developed and released three improved root-knot nematode resistant rootstocks, �Matador�, �Minotaur�, and �Kingfisher�. These resistant rootstocks demonstrate improved yield when compared to Freedom rootstock, an industry standard. We also released a precocious flowering grape variety, Scout, for breeding and genetics research. Grapevine genetics and breeding is slower than in other crop plants because of its long life cycle from seedling to fruiting. �Scout� grapevine seedlings can flower in as few as 100 days from seed. Furthermore, we released three lines of low vigor grapevine rootstocks. Some rootstock varieties are too vigorous for certain fertile vineyard soils. We invented three selections of grapevine rootstock that are slower growing than their diploid progenitor and are expected to produce lower vigor and vine size in fruitful scions grafted on them. In addition, we developed three new lines of pistillate-flowered dwarf grapevines for easy cross-hybridization. Accomplishments 01 High-resolution genetic maps for grapevine. Plant breeders and geneticists use DNA markers on genetic maps to track the location of genes underlying key traits, such as disease resistance and fruit quality. Akin to mile markers on highways, DNA markers reveal the context of the destination (the trait), and more frequent markers result in more precision in reaching the destination. ARS researchers at Geneva, New York and Ithaca, New York adapted a new genetic technology that resulted in a 10-fold increase in the resolution of DNA markers in grapevine, at a cost that is affordable to grape breeders. As a result, traits such as powdery mildew resistance, flower sex, seedlessness, and berry color are being tracked in traditional grape breeding programs with drastically-improved precision. These markers enable breeders to identify and discard undesirable progeny within months of seed germination, saving years of effort and expense from the breeding and evaluation process. 02 Resistance to root-knot nematodes in grapevine. Root-knot nematodes (RKN) are a chief pest of vineyards across California and the United States. The most cost-effective solution to control RKNs in vineyards is to use nematode resistant rootstocks. Breeding for nematode- resistant rootstocks is a long and laborious process, which may take more than one decade to obtain commercially acceptable resistant rootstocks. Furthermore, the occurrence of multiple RKN species and the constant emergence of new virulent populations in vineyards make the conventional breeding for nematode resistant rootstocks even more challenging. To provide an alternative solution to this challenge, ARS researchers at Geneva, New York evaluated a biotech-based solution for controlling RKNs in grapes. The basic idea is that, through some sophisticated designs, when nematodes try to feed on the roots of the engineered grape rootstocks, their feeding is suppressed such that the nematodes will not be able to feed or reproduce. We have successfully demonstrated this concept. This technology can provide an important alternative solution, complementary to the conventional breeding, to controlling RKNs in grapevines.
Impacts
(N/A)
Publications
- Saito, S., Dunne, K., Evans, K., Barry, K., Wilcox, W., Cadle Davidson, L. E. 2013. Optimisation of techniques for quantification of Botrytis cinerea in grape berries and receptacles by quantitative polymerase chain reaction. Australian Journal of Grape and Wine Research. 19:68-73.
- Asalf, B., Gadoury, D., Tronsmo, A.M., Seem, R., Cadle Davidson, L.E., Brewer, M., Stensvand, A. 2013. Temperature regulates the initiation of cleistothecia in powdery mildew of strawberry. Phytopathology. 103:717-724.
- Yang, Y., Jittayasothorn, Y., Chronis, D.N., Wang, X., Cousins, P., Zhong, G. 2013. Molecular characteristics and efficacy of 16D10 siRNAs in inhibiting root-knot nematode infection in transgenic grape hairy roots. PLoS One. 8(7):e69463. doi: 10.1371/journal.pone.0069463.
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): 1. Develop improved genetic systems for functional genomics research of grape pest and disease resistance. 2. Characterize the genetic, genomic, proteomic, and other aspects of the interaction of grapevines and fungal and oomycete pathogens to identify the key determinants of resistance, tolerance, and susceptibility. 3. Improve grapevine rootstocks through identification, development, deployment, and enhancement of resistance to pests and diseases. Approach (from AD-416): Develop a grapevine system with reduced juvenile period for rapid candidate gene evaluation of disease and pest resistance. Optimize and evaluate the utility of a newly created dwarf grapevine system for investigating interactions between grapevines and key pests and pathogens. Determine race-specificity of powdery mildew resistance in Vitis species. Develop molecular markers associated with resistance to grape powdery mildew. Characterize the relationship between biochemical changes in the berry-powdery mildew interface and developmentally- regulated resistance to powdery mildew on grape berries. Enhance non- race-specific resistance in Vitis vinifera to powdery mildew and/or downy mildew via knock-out of susceptibility loci. Characterize the genetic control of resistance to Meloidogyne species (root-knot nematodes) in grapevine. Develop molecular markers associated with resistance to root- knot nematodes. Develop grape rootstocks with enhanced resistance to root-knot nematodes. Evaluate the ability of rootstocks to mitigate symptoms of Pierce�s disease in grapevine rootstocks. Develop autotetraploid selections with reduced vigor induction and evaluate their pest resistance. DNA molecular markers can be used to track genes and positive alleles in breeding programs. We adapted a high resolution DNA marker platform called Genotyping-by-Sequencing (GBS) to identify genes underlying traits and to apply markers for selection in grape breeding programs. The GBS technology increased marker resolution 10-fold over previous high resolution marker platforms and 100-fold over standard SSR marker platforms, with a low per-sample cost. In 2012, we confirmed linkages of GBS markers with powdery mildew resistance and seedlessness. We applied GBS markers in over 6000 grape breeding progeny to identify elite seedlings for focused evaluation. Some muscadine grapevines (Vitis rotundifolia) from the Southeastern U.S. are naturally resistant to powdery mildew infection due to the Run1 resistance gene. In NY, we observed signs of powdery mildew infection on Run1-containing vines, even though the pathogen population had never been exposed to muscadine grapevines or the Run1 resistance gene until the past decade. We collected isolates of the powdery mildew fungus and evaluated their interaction with grapevines carrying the Run1 gene. The powdery mildew isolates could grow well on these grapevines, but not on grapevines with other resistance genes. When Run1 was combined with other resistance genes, powdery mildew was effectively halted. These results are guiding grape breeders, grape pathologists, and grape growers to protect Run1 for future generations. Around the world, early season epidemics of grape powdery mildew progress more slowly than predicted. We showed that pre-treatment of susceptible grape leaves by exposure to cool, springtime temperatures (eg, 4 to 8�C for as little as 5 minutes) reduced powdery mildew disease. This may partly account for discrepancies in disease forecast modeling. Historical weather data indicated that early-season cold events in this temperature range occur commonly across most viticulture regions worldwide, and may partially explain: unexpectedly slow development of powdery mildew during the first month after budbreak, and the sudden increase in epidemic development once seasonal temperatures increase above the threshold for acute cold events. This knowledge may reduce the number of pesticide sprays and improve disease forecasting models. Genotyping microarrays are a common technology used to assay genetic variation. These arrays rely on the matching of a sample�s DNA to a sequence from a reference plant. High diversity plant species such as grapevine, data from the array can be difficult to interpret. We developed a genetic mapping method that is easy to compute and can be used in any mapping population for which genotyping microarray data have been collected. We demonstrated its use in mapping three simple traits (color, flower sex and resistance to powdery mildew) in grapevine by using raw fluorescence data instead of software-generated sequence predictions, and with population sizes smaller than previously used. This advance will reduce the cost and increase the impact of genotyping microarrays in high diversity species, which includes many of the plants we rely on for food. Accomplishments 01 Three lines of low vigor grapevine rootstocks. Rootstocks that provide protection against pests and diseases are a sustainable method for managing damage to grapevine roots. Rootstocks influence the size and growth rate of the fruitful scion varieties grafted on them. Some rootstock varieties are too vigorous for certain fertile vineyard soils, but these rootstocks have useful or unique pest and disease resistance. ARS researchers at Geneva, New York invented three selections of a usefu but highly invigorating grapevine rootstock that are slower growing with shorter internodes than their diploid progenitor and are expected to produce lower vigor and lower vine size in fruitful scions grafted on th Special nursery propagation, production, and grafting methods will be needed for commercialization of these selections. A Material Transfer Agreement with a leading grapevine nursery is in place for these three lines. 02 Dwarf grapevines. ARS researchers at Geneva, New York developed the Pixi dwarf grapevine variety in cooperation with the University of California and released the variety in 2007. The Pixie dwarf grapevine is gibberellic acid insensitive. Pixie grapevines have very short internod and produce inflorescences in preference to tendrils. Seedlings carryin the semidominant dwarfing gene inherited from Pixie can begin to flower as few as three months. We used Pixie as a pollen parent in crosses wit rootstocks to develop three lines of dwarf grapevines. These dwarf grapevines are more vigorous than Pixie, showing faster growth, but the vines are still compact and show inflorescences in preference to tendril The three new lines of dwarf grapevines are pistillate flowered, with on functional female parts. This is in contrast to the Pixie grapevine, which is self fertile, self pollinating, and has functional male and female parts. Since the new lines are pistillate flowered, they can easily be used in hybridization with other grapevine varieties. The new lines flower continuously when cultivated in a greenhouse. One of the lines carries the N allele for root-knot nematode resistance inherited from Freedom rootstock. The new lines of dwarf grapevine could be usefu for breeding and genetics studies and as parent material for grapevine rootstocks.
Impacts
(N/A)
Publications
- Mahanil, S., Ramming, D.W., Cadle-Davidson, M., Owens, C.L., Garris, A., Myles, S., Cadle Davidson, L.E. 2012. Development of marker sets useful in the early selection of Ren4 powdery mildew resistance and seedlessness for table and raisin grape breeding. Journal of Theoretical and Applied Genetics. 124:23-33.
- Frenkel, O., Portillo, I., Brewer, M., Peros, J., Cadle Davidson, L.E., Milgroom, M. 2012. Development of microsatellite markers from the transcriptome of Erysiphe necator for analyzing population structure in North America and Europe. Plant Pathology. 61:106-119.
- Cadle Davidson, L.E., Brooks, S., Gadoury, D., Kozma, P., Reisch, B. 2011. Natural infection of Run1-positive vines by na�ve genotypes of Erysiphe necator. Vitis. 50:173-175.
- Wakefield, L., Gadoury, D., Cadle Davidson, L.E., Seem, R. 2012. Initiation of conidiation in Erysiphe necator is regulated by prior vegetative growth, inoculum density and light. Phytopathology. 102:65-72.
- Liang, Z., Yang, Y., Chen, L., Zhong, G. 2012. Polyphenolic composition and content in the ripe berries of wild Vitis species. Food Chemistry. 132:730-738.
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) 1. Develop improved genetic systems for functional genomics research of grape pest and disease resistance. 2. Characterize the genetic, genomic, proteomic, and other aspects of the interaction of grapevines and fungal and oomycete pathogens to identify the key determinants of resistance, tolerance, and susceptibility. 3. Improve grapevine rootstocks through identification, development, deployment, and enhancement of resistance to pests and diseases. Approach (from AD-416) Develop a grapevine system with reduced juvenile period for rapid candidate gene evaluation of disease and pest resistance. Optimize and evaluate the utility of a newly created dwarf grapevine system for investigating interactions between grapevines and key pests and pathogens. Determine race-specificity of powdery mildew resistance in Vitis species. Develop molecular markers associated with resistance to grape powdery mildew. Characterize the relationship between biochemical changes in the berry-powdery mildew interface and developmentally- regulated resistance to powdery mildew on grape berries. Enhance non- race-specific resistance in Vitis vinifera to powdery mildew and/or downy mildew via knock-out of susceptibility loci. Characterize the genetic control of resistance to Meloidogyne species (root-knot nematodes) in grapevine. Develop molecular markers associated with resistance to root- knot nematodes. Develop grape rootstocks with enhanced resistance to root-knot nematodes. Evaluate the ability of rootstocks to mitigate symptoms of Pierce�s disease in grapevine rootstocks. Develop autotetraploid selections with reduced vigor induction and evaluate their pest resistance. Understanding how rootstocks and scions interact is important for grape production and variety development. To determine whether or not dwarf phenotype can be transmitted from rootstocks to scions, Pixie, a dwarf grapevine, was used as rootstock and grafted to Thompson Seedless, which has a normal plant stature. No dwarf phenotype was observed in the scion of the grafted plants. This result was in contrast with what was observed in apples in which dwarf rootstocks can pass their dwarf characteristics to scions. The result suggested that rootstock-scion interactions were trait- and species-specific. Whole plant functional testing of grapevine genes is challenging due to large plant size and the time required from transformation to fruiting. In order to develop a small, rapid cycling, and easily transformed grapevine variety, we introduced several plant-growth related genes including VvGAI, VvFT and AtBRC1 into grapevines to determine how these genes affect plant architecture and growth. We observed that these genes significantly impacted plant height, branching and other growth and development traits. This knowledge will help us create new varieties with improved architecture and other growth and development traits for functional genomics research as well as variety improvement. We are interested in exploring the feasibility of developing a biotech solution for controlling root-knot nematodes in grapevines. We developed a transgenic hairy root system for evaluating root-knot nematode resistance genes in grape. We characterized the responses of 14 grape species to the inoculation of 3 Agrobacterium strains and observed that Agrobacterium strains, plant genotypes, and inoculation sites all significantly impacted the success of inducing hairy roots. An optimized hairy-root induction system was established and is being used as a high through-put system for evaluation of genes conferring nematode resistance to grapes. To develop new cultivars with disease resistance, we used molecular markers to screen 1704 breeding progeny from 20 independent cross- hybridizations. These markers, genetically linked with known disease resistance genes, enabled selection of progeny with multiple disease resistance genes, for improved durability and breadth of resistance. Grapevine seedlings often do not flower until after several seasons. This growth habit limits the progress of genetics and breeding research, since such research is often limited by generation time. In a cross of a precocious flowering grapevine with a rootstock, we demonstrated that precocious flowering is conditioned by a single semi-dominant allele. The population segregated for leaf disk color/berry flesh color and flower sex type in addition to precocious flowering. Since more grandparental phenotypes were recovered than would be expected randomly, it may be that precocious flowering is genetically linked to flower sex and leaf disk color, although this could be an artifact of flower sex type on sexual maturation. This research enables grape breeders to use the publically available germplasm to more specifically address accelerating population improvement and genetics research. Accomplishments 01 Identified important grape powdery mildew genes. Although powdery milde is economically the most important fungal pathogen of grapevines, it cannot be grown in pure culture, thereby limiting knowledge about its genetics. In order to identify and target weaknesses in powdery mildew biology, ARS researchers at Geneva, NY, sequenced and described all of t genes expressed by grape powdery mildew, as part of an international collaboration spanning powdery mildews of fruits, vegetables, grasses, a weeds. Researchers discovered powdery mildew genes required for reproduction, cold survival, and fungicide tolerance. This improved knowledge of powdery mildew genetics provides new targets for disease management of a fungus that costs grape growers $100 to 400 per acre per year. 02 Released three new nematode resistant rootstocks. Root-knot nematodes a a chief pest of vineyards across California and the United States. Resistant rootstocks provide protection against nematodes and are an alternative to pesticides. ARS researchers at Geneva, NY, used cross breeding to combine nematode resistance and useful traits into new rootstock selections and evaluated pest resistance, viticultural performance, and other important qualities to identify candidate rootstocks. Three improved root-knot nematode resistant rootstocks, �Matador�, �Minotaur�, and �Kingfisher�, were released in 2010. These nematode resistant rootstocks demonstrate improved yield efficiency when compared to Freedom rootstock, an industry standard, with more yield of grapes in relation to weight of cane prunings. All three rootstocks are available as virus tested plant material from the University of Californ Foundation Plant Services; grapevine nurseries have acquired these varieties for commercial increase blocks. 03 Released precocious flowering grape variety for breeding and genetics research. Grapevine genetics and breeding is slower than in other crop plants because grapevines usually need three to four years before they flower and fruit. �Scout� is a new grape variety that provides accelerat flowering for breeding and genetics research. �Scout� was developed by ARS researchers at Geneva, NY, from a cross of �Rubired� wine grape with wild grape species. �Scout� grapevine seedlings may flower in as few as 100 days from seed. The development of this new variety will greatly accelerate grape breeding progress for economically important traits. �Scout� vines flowers profusely and continuously in a greenhouse. �Scou develops deep red color in leaf disk assays; this trait can be used to demonstrate hybrid parentage of populations. �Scout� is a male flowered vine, but seedlings can be self fertile or male flowered.
Impacts
(N/A)
Publications
- Ramming, D.W., Gabler, F., Smilanick, J.L., Cadle Davidson, M., Barba, P., Consolie, N.H., Mahanil, S., Cadle Davidson, L.E. 2011. A single dominant locus Ren4 confers non-race-specific penetration resistance to grapevine powdery mildew. Phytopathology. 101(4):502-508.
- Wakefield, L., Gadoury, D.M., Seem, R.C., Milgroom, M.G., Sun, Q., Cadle Davidson, L.E. 2011. Differential gene expression during conidiation in the grape powdery mildew fungus, Erysiphe necator. Phytopathology. 101:839- 846.
- Gadoury, D., Cadle Davidson, L.E., Wilcox, W., Dry, I., Seem, R., Milgroom, M. 2012. Grapevine powdery mildew (Erysiphe necator): a fascinating system for the study of the biology, ecology, and epidemiology of an obligate biotroph. Molecular Plant Pathology. 13:1-16.
- Brewer, M.T., Cadle Davidson, L.E., Cortesi, P., Spanu, P.D., Milgroom, M. G. 2011. Identification and structure of the mating-type locus and development of PCR-based markers for mating type in powdery mildew fungi. Fungal Genetics and Biology. 48:704-713.
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) 1. Develop improved genetic systems for functional genomics research of grape pest and disease resistance. 2. Characterize the genetic, genomic, proteomic, and other aspects of the interaction of grapevines and fungal and oomycete pathogens to identify the key determinants of resistance, tolerance, and susceptibility. 3. Improve grapevine rootstocks through identification, development, deployment, and enhancement of resistance to pests and diseases. Approach (from AD-416) Develop a grapevine system with reduced juvenile period for rapid candidate gene evaluation of disease and pest resistance. Optimize and evaluate the utility of a newly created dwarf grapevine system for investigating interactions between grapevines and key pests and pathogens. Determine race-specificity of powdery mildew resistance in Vitis species. Develop molecular markers associated with resistance to grape powdery mildew. Characterize the relationship between biochemical changes in the berry-powdery mildew interface and developmentally- regulated resistance to powdery mildew on grape berries. Enhance non- race-specific resistance in Vitis vinifera to powdery mildew and/or downy mildew via knock-out of susceptibility loci. Characterize the genetic control of resistance to Meloidogyne species (root-knot nematodes) in grapevine. Develop molecular markers associated with resistance to root- knot nematodes. Develop grape rootstocks with enhanced resistance to root-knot nematodes. Evaluate the ability of rootstocks to mitigate symptoms of Pierce�s disease in grapevine rootstocks. Develop autotetraploid selections with reduced vigor induction and evaluate their pest resistance. To develop new cultivars with disease resistance to powdery mildew and downy mildew, we germinated 3000 seeds from 13 independent hybridizations for evaluation of disease resistance.We analyzed the genome of the powdery mildew pathogen and identified genes required for virulence and sporulation. Functional analysis of these genes enables the development of novel disease management strategies that target the weaknesses of the pathogen. We identified eleven easily propagated, nematode resistant rootstock selections that can provide an alternative to methyl bromide fumigation. In order to identify these candidate rootstocks, we tested the propagation ability of 190 selections and 176 selections showed that they are easily propagated. 80 selections were retested to confirm nematode resistance in replicated trials. An optimized hairy-root induction system was established and will be used as a high through-put system for evaluating nematode resistance genes in grape, overcoming limitations of the conventional rootstock breeding. We characterized the responses of 14 grape species to the inoculation of 3 Agrobacterium strains and observed that plant genotypes and inoculation sites significantly impacted the success hairy root induction. In order to develop a small, rapid cycling, and easily transformed grapevine variety, we introduced several plant-growth related into grapevines to see how these genes might affect plant architecture and growth cycle. We observed that these genes had significant impact on plant heights, branching and other growth traits. This knowledge will help us design a better strategy for creating a new grapevine variety for functional genomics research. Grapevine seedlings often do not flower until after several seasons. We showed inheritance of precocious flowering of interspecific hybrid populations of grapevine seedlings. The hybrid grapevine seedlings flowered precociously within four months; they did not receive chilling hours or dormancy, typically required for regular flowering in mature grapevines. We have now shown multiple generations of inheritance of precocious flowering. Seedlings of crosses of select precocious and continuously reblooming parents to rootstock and wine grape varieties show precocious flowering, indicating broad application of this source of precocious flowering in developing model grapevine varieties for research. To identify the genetic control of resistance against aggressive root- knot nematodes, the allelism of a putative new allele for resistance inherited from Vitis cordifolia was tested to determine its relationship to the N allele. Based on progeny testing, the novel allele from V. cordifolia is not allelic to the N allele. The independent assortment of resistance alleles indicates that the N allele and the V. cordifolia allele represent forms of different genes. The V. cordifolia allele provides protection to a broader range of nematodes than does the N allele and is deployed in resistant rootstock selections. Determination of the non-allelic nature of the N and the V. cordifolia allele will facilitate breeding improved rootstocks and gene pyramiding to enhance resistance durability Accomplishments 01 Accelerating introduction of powdery mildew resistant table, raisin, and wine grape cultivars through marker assisted selection. New cultivars with powdery mildew resistance are desired by grape growers, but durability of this resistance is critical due to the cost of vineyard establishment and the necessary longevity of grapevines. ARS Researcher at Geneva, New York successfully documented that some resistances in breeding programs could be overcome quickly by common pathogen isolates and communicated a need for breeders to pyramid multiple resistance gene in new cultivars. We are applying molecular markers to track these resistance genes and further the development of varieties with multiple resistance gene durability. Further, we identified a source of powdery mildew resistance that prevents the pathogen penetration and appears to durable by itself. We are using molecular markers to track the introgression of this resistance gene into high quality raisin, table, a wine grapes. Varieties bred with broad spectrum powdery mildew resistan would save growers between $100 to 400 per acre per year in pesticide costs and reduce direct and indirect effects of pesticide application. 301 2 B 2006 301 2 C 2006 301 3 B 2006 301 3 C 2006 303 3 A 2006
Impacts
(N/A)
Publications
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Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) 1. Develop improved genetic systems for functional genomics research of grape pest and disease resistance. 2. Characterize the genetic, genomic, proteomic, and other aspects of the interaction of grapevines and fungal and oomycete pathogens to identify the key determinants of resistance, tolerance, and susceptibility. 3. Improve grapevine rootstocks through identification, development, deployment, and enhancement of resistance to pests and diseases. Approach (from AD-416) Develop a grapevine system with reduced juvenile period for rapid candidate gene evaluation of disease and pest resistance. Optimize and evaluate the utility of a newly created dwarf grapevine system for investigating interactions between grapevines and key pests and pathogens. Determine race-specificity of powdery mildew resistance in Vitis species. Develop molecular markers associated with resistance to grape powdery mildew. Characterize the relationship between biochemical changes in the berry-powdery mildew interface and developmentally- regulated resistance to powdery mildew on grape berries. Enhance non- race-specific resistance in Vitis vinifera to powdery mildew and/or downy mildew via knock-out of susceptibility loci. Characterize the genetic control of resistance to Meloidogyne species (root-knot nematodes) in grapevine. Develop molecular markers associated with resistance to root- knot nematodes. Develop grape rootstocks with enhanced resistance to root-knot nematodes. Evaluate the ability of rootstocks to mitigate symptoms of Pierce�s disease in grapevine rootstocks. Develop autotetraploid selections with reduced vigor induction and evaluate their pest resistance. Significant Activities that Support Special Target Populations Powdery mildew and downy mildew are serious grapevine pathogens that reduce grape yield and quality. To help U.S. grape breeders select for resistance to mildews, more than 850 advanced breeding lines, cultivars, and segregating progeny (over 10,000 replicate samples) were screened. In order to identify easily propagated candidate rootstocks, 156 selections resistant to aggressive virulent root-knot nematode populations were tested for rooting ability under greenhouse conditions. Of the selections tested, 142 rooted at 70% or above without the addition of rooting hormones or bottom heat. These selections are candidates for additional root-knot nematode resistance evaluation and horticultural evaluation. Developed a transgenic hairy root system for evaluating genes in grapevine roots. We evaluated the responses of 14 grape species to inoculation with three Agrobacterium strains and observed that two of the grape species responded to the inoculation positively in producing hairy roots. These results will lead to the development of a hairy root testing system for high through-put evaluation of genes that may confer grapevine resistance to root-knot nematodes and other root pests and diseases. In order to develop a small, easily transformed grapevine variety, we evaluated several plant-growth related genes including VvGAI, VvFT and AtBRC1 in the model plant Arabidopsis. We observed that these genes had significant impact on plant heights and other growth traits. This knowledge will help us to design a better strategy for creating a new grapevine variety for functional genomics research. Demonstrated flowering of interspecific hybrid populations of grapevine seedlings as preciously as the 10th node above the cotyledons. These seedlings were grown in a greenhouse and did not receive chilling hours or dormancy, typically required for regular flowering in physiologically mature grapevines. Selected individual seedlings show continuous flowering from latent buds under greenhouse conditions and can be propagated in tissue culture, which will facilitate their utilization in genomics and breeding research. To identify the genetic control of resistance against aggressive virulent root-knot nematodes, the allelism of putative new allele for nematode resistance inherited from Vitis rufotomentosa Small was tested to determine its relationship to the N allele. Based on progeny testing, the novel allele from V. rufotomentosa is not allelic to the N allele sensu Lider (found in Harmony and Freedom rootstocks). The independent assortment of the nematode resistance alleles indicates that the N allele and the V. rufotomenstosa allele represent forms of different genes. The V. rufotomenstosa allele provides protection to a broader range of nematode populations than does the N allele and is deployed in nematode resistant rootstock selections. Determination of the independent and non- allelic nature of the N and the V. rufotomenstosa allele will facilitate breeding superior nematode resistant rootstocks and allow gene pyramiding to enhance durability of resistance.
Impacts
(N/A)
Publications
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Progress 10/01/07 to 09/30/08
Outputs
Progress Report Objectives (from AD-416) 1. Develop improved genetic systems for functional genomics research of grape pest and disease resistance. 2. Characterize the genetic, genomic, proteomic, and other aspects of the interaction of grapevines and fungal and oomycete pathogens to identify the key determinants of resistance, tolerance, and susceptibility. 3. Improve grapevine rootstocks through identification, development, deployment, and enhancement of resistance to pests and diseases. Approach (from AD-416) Develop a grapevine system with reduced juvenile period for rapid candidate gene evaluation of disease and pest resistance. Optimize and evaluate the utility of a newly created dwarf grapevine system for investigating interactions between grapevines and key pests and pathogens. Determine race-specificity of powdery mildew resistance in Vitis species. Develop molecular markers associated with resistance to grape powdery mildew. Characterize the relationship between biochemical changes in the berry-powdery mildew interface and developmentally- regulated resistance to powdery mildew on grape berries. Enhance non- race-specific resistance in Vitis vinifera to powdery mildew and/or downy mildew via knock-out of susceptibility loci. Characterize the genetic control of resistance to Meloidogyne species (root-knot nematodes) in grapevine. Develop molecular markers associated with resistance to root- knot nematodes. Develop grape rootstocks with enhanced resistance to root-knot nematodes. Evaluate the ability of rootstocks to mitigate symptoms of Pierce�s disease in grapevine rootstocks. Develop autotetraploid selections with reduced vigor induction and evaluate their pest resistance. Significant Activities that Support Special Target Populations Disease resistance evaluation Powdery mildew is a serious grapevine pathogen that reduces grape yields and quality. In order to identify sources of resistance to powdery mildew, more than 1200 accessions were evaluated. We identified variation for resistance within and among species; the most resistant accessions permit no mildew growth. This information will permit grape breeders to more effectively use the accessions to develop improved varieties with durable disease resistance and characterize resistance mechanisms. NP 301 Plant Genetic Resources, Genomics and Genetic Improvement Component 3. Genetic Improvement of Crops Problem Statement 3B: Capitalizing on Untapped Genetic Diversity. NP 303 Plant Diseases Component 3: Plant Disease Resistance Problem Statement 3B. Disease resistance in new germplasm and varieties. Functional genomics technology development Evaluating grapevine gene function is challenging due to the lengthy transformation process. In order to accelerate functional gene testing, we adapted a transient gene expression system (previously used in one grape species) for use in multiple species, including those with powdery mildew resistance. Confirmed gene function will be a platform for identifying and utilizing genes for foliar disease resistance, permitting selection of improved varieties. Whole plant functional testing of grapevine genes is challenging due to large plant size and the time required from transformation to fruiting. In order to develop a small, easily transformed grapevine variety, we evaluated the impact of ten allelic forms of the grape GAI gene on plant growth and development in the model plant Arabidopsis. We observed that different grape GAI gene allelic forms have different impacts on Arabidopsis growth, architecture and flowering time. This observation advanced our understanding of grape GAI gene function and provides an opportunity to create a new variety suited for grape functional genomics research. NP 301 Plant Genetic Resources, Genomics and Genetic Improvement Component 2: Crop Informatics, Genomics, and Genetic Analyses Problem Statement 2B: Structural Comparison and Analysis of Crop Genomes. Problem Statement 2C: Genetic Analyses and Mapping of Important Traits. Grape Scion Disease Resistance Characterization Developing grapes can be attacked by pathogens that reduce grape quality and yield. The pathogens interact with the cuticle, the outer layer of the grape. In order to identify possible disease resistance components in the cuticle, we characterized cuticle development and resolved and identified proteins from wild and cultivated grapes at several developmental stages. The new information on cuticle biochemistry and development will enable isolation of specific components that condition pathogen resistance and impact berry growth. NP 301 Plant Genetic Resources, Genomics and Genetic Improvement Component 2: Crop Informatics, Genomics, and Genetic Analyses Problem Statement 2C: Genetic Analyses and Mapping of Important Traits. NP 303 Plant Diseases Component 3: Plant Disease Resistance Problem Statement 3A. Mechanisms of Plant Disease Resistance.
Impacts
(N/A)
Publications
- Gee, C., Gadoury, D., Cadle Davidson, L.E. 2008. Ontogenic resistance to Uncinula necator varies by genotype and tissue type in a diverse collection of Vitis spp. Plant Disease. 92:1067-1073.
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