Breeding for Phytophothora capsici Resistance: Study in QTL Analysis for Disease Resistance and Horticultural Traits in Bell Pepper (Capsicum annuum)

摘要

Bell pepper (Capsicum annuum) is a highly consumed vegetable in the U.S. However, it is also highly susceptible to many diseases. Phytophthora capsici is one of the major pathogens of bell pepper production. Introgression of sources of genetic resistance into commercial varieties is an effective approach for disease management. In this study, resistance loci for different isolates in a pepper recombinant inbred line (RIL) population, along with some desirable traits such as fruit size and unfavorable traits associated with the resistant parent, were identified. Quantitative trait loci (QTL) analysis identified the major components of P. capsici resistance, as well as components of resistance that were isolate-specific. QTL for organ (fruit and leaf) size clustered into a few loci in the pepper genome. The linkage map and correlation study revealed relationships among the traits. Genetic and physical genomic maps were used to investigate the candidate genes for all traits. R-gene complexes were proposed to contain the candidate genes for the resistance at the major QTL, whereas three genes on chromosomes 1, 2 and 3 were suggested for organ size. Combining the phenotypic and genotypic data from all traits, a RIL was selected for the resistant parent and crossed to bell-type varieties to develop marketable bell pepper lines containing broad genetic resistance for P. capsici. .