Location: Crops Pathology and Genetics Research2013 Annual Report
1a. Objectives (from AD-416):
Screen grape cultivars with the causal agents of Eutypa dieback, Esca, and Botryosphaeria Canker.
1b. Approach (from AD-416):
Planting disease-resistant culitvars is a time-tested and sustainable approach to disease management. Based on field observations and published research on resistance to wood-canker diseases, we know that a range of resistance exists among commercial cultivars of almond and grape. We propose to improve screening assays for evaluating both commercial cultivars and USDA germplasm repositories for sources of disease resistance. Our approach is to screen plant materials from both commericial nurseries and the USDA-ARS National Clonal Germplasm Repository.
3. Progress Report:
This project was established in support of objective 1 of the in-house project, which is to develop sustainable disease control practices for grapevines. The goal of this project is to screen grape cultivars with the causal agents of Eutypa dieback, Esca, and Botryosphaeria Canker. The experiments were set up in order to identify markers of resistance to wood canker disease in four grape cultivars, and also to understand the basis of this resistance. The four grape cultivars included three wine grape cultivars (i.e., Cabernet Sauvignon, Merlot, Chardonnay) and one table grape cultivar (i.e., Thompson seedless). They have known susceptibility/tolerance to wood-canker pathogens. We completed the anatomical analysis of the one year-old wood of the four grapevine cultivars. We found that the hydraulic architecture, and especially the size of the vessels, of susceptible cultivars and tolerant cultivars are different. This suggests that wood anatomy and tolerance to wood-canker diseases may be connected. We developed research collaboration with a scientist in the Department of Botany and Plant Sciences at the University of California, Riverside, to gain insight on the physiology of these four cultivars, and specifically hydraulic conductivity, vulnerability to cavitation, wood density and stomatal conductance. We also inoculated 550 cuttings of the same four cultivars with four major pathogens causing wood-canker diseases (I.e., Eutypa lata, Neofusicoccum parvum, Phaeomoniella chlamydospora, and Phaeoacremonium aleophilum). Plant anatomy, physiology and chemistry will be analyzed later this year. In addition, research collaboration with a scientist in the Viticulture and Enology Department, University of California, Davis, was initiated to study gene expression of three of these fungi during colonization of susceptible (Cabernet Sauvignon) and tolerant (Merlot) grape varieties. The genome of these fungi were sequenced and published. Fungal transcriptomic analyses of the infected grape cultivars will be completed later this year. Draft Genome Sequence of the Grapevine Dieback Fungus Eutypa lata UCR-EL1 Genome Announc. May/June 2013 1:e00228-13; doi:10.1128/genomeA.00228-13 Draft Genome Sequence of Neofusicoccum parvum Isolate UCR-NP2, a Fungal Vascular Pathogen Associated with Grapevine Cankers Genome Announc. May/June 2013 1:e00339-13; doi:10.1128/genomeA.00339-13 Draft Genome Sequence of the Ascomycete Phaeoacremonium aleophilum Strain UCR-PA7, a Causal Agent of the Esca Disease Complex in Grapevines Genome Announc. May/June 2013 1:e00390-13; doi:10.1128/genomeA.00390-13