Genetic analysis of resistance to tomato late blight in Solanum pimpinellifolium accession PI 163245

Abstract

AbstractLate blight (LB), caused by Phytophthora infestans, is one of the most devastating diseases of tomato (Solanum lycopersicum) worldwide. Due to the emergence of new and aggressive P. infestans isolates, identifying new genetic resistance to LB is a priority in tomato breeding. Recently, we reported the identification of several Solanum pimpinellifolium accessions with strong LB resistance. In this study, we investigated the utility of resistant accession PI 163245 for tomato breeding by examining heritability (h2) of resistance and the response to selection for resistance. Estimates of h2 based on F2 : F3 and F3 : F4 parent : offspring correlation analyses averaged 0.79 and 0.94, respectively, suggesting the heritable nature of LB resistance in PI 163245. Analysis of response to selection for resistance from F2 to F4 generations indicated a realized h2 of 0.63, confirming the utility of this resistance in tomato breeding. Two methods of estimating the minimum number of loci involved indicated the presence of one major resistance locus. Currently, genetic mapping and breeding efforts are underway to further confirm the viability of this accession for improving tomato LB resistance.