Potential Application of TRAP (Targeted Region Amplified Polymorphism) Markers for Mapping and Tagging Disease Resistance Traits in Common Bean

Abstract

Genetic resistance is an important component of integrated strategies used to control problematic diseases in common bean (Phaseolus vulgaris L.). Molecular linkage maps have been used to identify, tag, and map disease resistance genes and QTL in common bean, leading to improved breeding strategies and implementation of marker‐assisted selection. Most widely used marker types, random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphisms (AFLP), for linkage mapping in bean are located randomly throughout the genome and associate with particular traits by chance. We sought to determine the potential application of a new marker system, TRAP, which uses expressed sequence information and a bioinformatics approach to generate polymorphic markers around targeted candidate gene sequences. TRAP markers were amplified by fixed primers designed against sequenced expressed sequence tag (EST) associated with disease resistance in the Compositae Genomics database or against sequenced resistance gene analog (RGA) from common bean. Seventeen of 85 TRAP markers located in the BAT 93/Jalo EEP558 core mapping population mapped in the vicinity of R genes. Six of 21 TRAP markers generated in the Dorado/XAN 176 mapping population were linked with newly identified QTL, two conditioning resistance to ashy stem blight (14% and 16% of the phenotypic variation explained, R2), and one each conferring resistance to Bean golden yellow mosaic virus (BGYMV) (15%) and common bacterial blight (30%). The TRAP marker system has potential for mapping regions of the common bean genome linked with disease resistance.