Widening genetic diversity to breed innovative grapevine rootstocks

Abstract

150 years ago grafting was identified as the most efficient method to combat phylloxera, this stimulated the active breeding of grapevine rootstocks and provided numerous rootstocks that are still in use today. Since then and over the 20th century, only a few new genotypes were been released. Recent challenges, such as the requirement to reduce environmental impact and adapt viticulture to climate change, has resumed interest in rootstock breeding. As other institutes, INRAE and affiliated French organizations have initiated a new breeding program with the objective to enlarge the range of phylloxera-tolerant rootstocks which also have the ability to control soil-borne pests such as nematodes and have increased tolerance to abiotic stresses such as drought. To achieve this, we explore the potential of species, which have not yet been used for rootstock selection, and have developed modern selection approaches based on molecular data.

Over the past 20 years, Muscadine and other Vitis accessions have been screened intensively for their ability to inhibit the multiplication of nematodes such as Xiphinema index and Meloidogyne spp. Interesting genotypes have been selected as parents for crosses. Molecular markers have also been identified and are currently used in the breeding program. Although muscadine-based genotypes are difficult to cross, several new hybrids are under selection.

Recently, we have also begun to characterize the genetic architecture of rooting patterns and responses to drought in wild Vitis spp. and biparental populations. We have found that genotypes can adopt different drought adaptation strategies by combining specific combinations of traits. This knowledge will be leveraged so that the most relevant traits related to drought tolerance will be used to select the most interesting accessions in our breeding schemes.