Two-reference GWAS uncovers heat-stress-dependent bacterial wilt resistance in tomato

Researchers including Adrien Belny, Henri Desaint, and colleagues publishing in PLOS Genetics have applied a two-reference genome-wide association study (GWAS) framework to identify resistance loci in tomato (Solanum lycopersicum) that are specific to plants simultaneously experiencing heat stress and infection by Ralstonia solanacearum, the pathogen responsible for bacterial wilt.

Conventional resistance-mapping studies typically assess disease response under standard temperature conditions. The team's approach, which draws on two reference genomes to improve variant resolution, was designed to capture resistance that is only expressed — or is substantially altered — when heat stress is applied concurrently. The authors describe the resistance detected as biologically relevant, distinguishing it from artefactual associations, and argue that climate-change projections make the heat-plus-pathogen interaction an increasingly important target for crop-improvement programmes.

The findings are relevant to plant geneticists working on Solanaceae, to crop breeders seeking durable disease resistance under warming conditions, and to researchers interested in genotype-by-environment interactions more broadly. The two-reference GWAS methodology may also be of interest to statisticians and bioinformaticians working on association mapping in species with complex or divergent reference sequences. Educators teaching quantitative genetics or plant genomics may find the interaction phenotyping design illustrative of the limits of single-environment association studies.