Demarcation of Genomic Regions Influencing the Non-blighting Trait in Tomatoes

One of the most significant diseases challenging tomato growers in Florida is bacterial spot. Infections often result in extensive blighting and defoliation. Bacterial spot disease management is hindered by many factors, including climatic conditions conducive to infection, susceptibility of germplasm, and lack of efficient chemical control options. Shifts in bacterial populations hamper breeding efforts relying on race-specific resistance genes. Current breeding strategies aim to utilize race-non-specific resistance QTL. We have identified such QTL in Fla. 630, a non-blighting (NB) tomato genotype that maintains healthy foliage despite moderate bacterial spot pressure. The primary objective of our project is to develop a set of genome-wide markers for use in marker-assisted breeding of NB cultivars. Using Fla. 630 as the NB donor, we developed three BC₁F₃ populations for QTL-mapping. We visually assessed individual plants for NB under field conditions to generate two pools representing extreme ends of the blighting distribution per population for selective genotyping. We are conducting marker-trait association analyses to identify genomic regions influencing the NB phenotype and will screen advanced selections along with segregating backcross populations for the SNPs putatively associated with NB to validate them.