Population dynamics in grapevine genotypes differing in susceptibility to Pierces disease.

• Author(s): Lin, Hong;
• Abstract: he xylem-limited bacterium Xylella fastidiosa is the causal agent of Pierces Disease (PD) in grapevines, for which breeding resistant cultivars will be a long-term management strategy. To accomplish this goal resistant germplasm must be identified and characterized. A genetically diverse group of grape species and selections was mechanically inoculated with X. fastidiosa, grown in a greenhouse and evaluated for the levels of bacterial concentrations in stem and leaf tissues by quantitative ELISA 113 d post inoculation. Concentrations of X. fastidiosa were affected by genotype, plant tissue, position on the plant relative to the point of inoculation, and interactions among these factors. Based on estimated concentrations of X. fastidiosa in stem samples at 113 d post inoculation, 9621-67, Muscadinia rotundifolia, Vitis arizonica/candicans, V. arizonica/girdiana, V. candicans, V. girdiana, V. nesbittiana, and V. shuttleworthii were resistant to PD. In contrast, V. vinifera, V. aestivalis, 9621-94, and V. champinii had very high X. fastidiosa concentrations in stem tissues. Sequential sampling of petioles/mid-veins of leaf blades at 34, 77, and 113 d post inoculation revealed different temporal patterns in X. fastidiosa concentrations among the grape genotypes. Estimates of X. fastidiosa concentrations decreased after the first sampling in M. rotundifolia, 9621-67, V. girdiana, and V. arizonica/candicans, but increased in all the other genotypes. Characterization of X. fastidiosa concentrations in a broad range of grape genotypes is useful for selection of promising genetic backgrounds for breeding of PD resistant grapevines.
• Publication Date: Feb 2007
• Journal: American Journal Of Viticulture And Enology