identification of ssr marker linked to leaf rust resistant gene lr24 and marker assisted transfer of leaf rust resistance genes into bread wheat

a study was conducted to identify ssr markers linked to leaf rust resistance genes lr24 and lr28 and to be used for marker-assisted selection (mas) to transfer both genes to a widely cultivated wheat variety mp 3299 under rainfed condition. f2 individuals of the cross mp 3299×nil pbw 343 were used for generating genotypic data employing closely linked scar markers s73719 and s421570 to lr24 and lr28, respectively, and further subjected to bulk segregant analysis. a total of 70 ssr markers that amplify sequences on long arm of chromosome 3d and long arm of chromosome 4a were used for polymorphism assay between the parents mp 3299 and nil pbw 343. eighteen ssrs were polymorphic between the parents, of which 10 were located on chromosome 3dl and eight on chromosome 4al. three ssr markers out of 18 polymorphic markers differentiated two contrasting bulks and further used for f2 genotyping. finally, one ssr marker i.e. ‘barc 71’ linked to scar marker scs73719 at a distance of 3.36 cm based on the per cent recombination frequency was identified. thus, the newly identified ssr marker barc 71 linked to lr24 can serve as a useful marker in gene pyramiding instead of scar marker scs73719.