Andy V. Nguyen, Cecilia Agüero, Hannele Padre, and M. Andrew Walker*
*Department of Viticulture and Enology, UC Davis, Davis, CA 95616 (awalker@ucdavis.edu)

Grapevine fanleaf virus (GFLV) causes fanleaf degeneration, one of the most economically severe viral diseases affecting grapevines worldwide. The disease can result in crop losses of up to 80% by greatly reducing fruit set, leading to small, seedless ‘shot berries’. Muscadinia rotundifolia, a North American grape species, has previously been shown as a valuable source of GFLV resistance. The objective of this work is to quantify GFLV resistance in the progeny from a cross between the susceptible commercial rootstock 101-14 Mgt. and M. rotundifolia cv. Trayshed, and to study the inheritance of this trait. For GFLV inoculation, two-node cuttings of GFLV-infected Vitis vinifera cv. Cabernet Sauvignon were grafted onto hardwood cuttings from 32 individuals of the 101-14 x Trayshed population. Five months after grafting and growing in the greenhouse, the roots of the surviving plants were assayed for GFLV using RT-qPCR. Here we present preliminary results of GFLV concentrations in different genotypes. This work provides insight into the inheritance of GFLV resistance from M. rotundifolia and continues our progress toward developing new rootstocks to ameliorate the effects of GFLV.

We gratefully acknowledge research funding from the California Grape Rootstock Improvement Commission.

Funding Support: Calif. Grape Rootstock Improvement Commission