Location: Grape Genetics Research2008 Annual Report
1a. 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.
1b. 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.
3. Progress Report
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.
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.