Unravelling the Genetic Control of Bacterial Wilt Resistance in Ryegrass: Achievements, Prospects and Challenges

Abstract

Xanthomonas translucens pv. graminis (Xtg) causes bacterial wilt, one of the most important forage grass diseases in temperate grasslands. Molecular genetic and genomic tools have the potential to significantly benefit resistance breeding and to enable targeted resistance management. In the past, a major QTL for bacterial wilt resistance was identified in Lolium multiflorum and Xtg was shown to rely on a non-canonical type III secretion system for plant infection. Recently, a number of candidate genes for bacterial wilt resistance were identified by comparing genomic sequences of resistant and susceptible parental plants and their progeny. Comparative genomics of different X. translucens pathovars allowed to identify virulence traits characteristic for Xtg. These candidate plant resistance genes together with the bacterial virulence factors provide an invaluable resource for the development of genomics assisted selection strategies. In addition, the well characterised plant genotypes and bacterial strains serve as an ideal model system to fully understand the complex L. multiflorum-Xtg interaction.