Downy mildew-resistant vines: defeated loci may compromise the effectiveness of other major resistance genes

The creation of new grapevine varieties that are naturally resistant to downy mildew is an essential strategy for reducing the use of fungicides in viticulture, a strategy that has demonstrated its potential thanks to the INRAE-ResDur breeding program. In this context, the combination of several downy mildew resistance genes in a single grapevine variety (pyramiding) is used to increase the durability of resistance. However, while pyramiding provides increased resistance in the vast majority of cases, resistance loci that are defeated by certain strains of downy mildew can act as Trojan horses, compromising the resistance provided by other major loci in certain pyramiding situations. The discovery of potentially negative interactions between major resistance loci therefore calls for further research to identify the most promising combinations of resistance genes for optimal resistance durability.

Publication: bioRxiv doi.org/10.1101/2025.04.25.650562
Contact: Philippe Hugueney