Genetic resources for breeding phylloxera-resistant rootstocks

Abstract

Grape phylloxera (Daktulosphaira vitifoliae Fitch) is a major insect pest that has had devastating effects in grape-growing regions worldwide. As a result, using phylloxera-resistant rootstocks is a key component of modern vineyard management. However, most commercially available rootstocks only offer limited resistance, allowing the insects to feed, reproduce, and spread. Therefore, there is an urgent need for rootstocks that are completely resistant to phylloxera. Complete resistance is characterized by the insect’s inability to feed or reproduce on the vine.

So far, the only source of complete resistance used in commercial rootstocks is the accession Cinerea Arnold, which belongs to Vitis cinerea var. cinerea. To broaden the genetic basis for complete phylloxera resistance, we have screened a collection of V. cinerea var. berlandieri from Texas, as well as Asian Vitis species V. armata and V. coignetia, for their responses to phylloxera. We identified promising candidate donors of new resistance traits and have begun initial efforts to introgress this resistance into new rootstocks.

Our long-term goal is to develop a complete and stable resistance to phylloxera, which can only be achieved by identifying and stacking resistance alleles from various wild Vitis species. This involves testing new material over several years and across different locations to evaluate its stability under diverse climatic and soil conditions, as well as against various genetic strains of phylloxera.