Grape phylloxera, Daktulosphaira vitifoliae (Fitch), is an important insect pest of grape and continues impact the world’s vineyards. It is native to North America but has spread to every region where grapes are grown, causing billions of dollars in damage. Rootstocks, bred from resistant North American grape species, have been used to control phylloxera for over 100 years. However, some, such as AXR#1, have failed, with catastrophic costs to the wine industry. To prevent another widespread failure, genetic mechanisms underlying grapevine response to phylloxera must be understood. This is the first study to address genetic control of galling, which indicates susceptibility. One hundred fourteen F2 progeny were screened with grape phylloxera originally collected on AXR#1 roots from Napa, Sonoma, and Mendocino counties. Total numbers of root galls, which are positively correlated with susceptibility, were recorded. Chi-square analyses showed that more than two genes are involved in segregation of resistance and susceptibility. DNA marker analysis on this hybrid grape population is in progress to correlate AFLP and SSR markers with resistance and susceptibility and create a linkage map. These markers will be useful in resistance breeding and serve as the basis for more detailed studies of resistance mechanisms in Vitis.
Species 1: Homoptera Phylloxeridae Daktulosphaira vitifoliae (grape phylloxera)
Keywords: rootstock, DNA
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