Marker-assisted transfer of two powdery mildew resistance genes to Egyptian bread wheat cultivars

Abstract Powdery mildew (PM) caused by Blumeria graminis f. sp. tritici , is one of the major wheat diseases in the world and development of resistant varieties is the safest and most economical approach for controlling this disease. Two PM resistance genes, PmTb7A.1 and PmTb7A.2 were previously transferred from Triticum boeoticum to hexaploid wheat lines along with the stem rust resistance gene Sr22 which is effective against the race Ug99 and located close to the resistance gene PmTb7A.1. The PM resistant Indian wheat lines were used in the current study to transfer these two PM resistance genes to the susceptible Egyptian bread wheat cultivars Sids12 and Gemmiza12 using marker assisted backcrossing. The generated BC 1 F 1 and BC 2 F 1 lines were screened using the flanking markers for both PM genes and Sr22 . Positive lines for linked markers for both PM genes and Sr22 were selected, and disease reactions were recorded for stripe, leaf, and stem rust and PM under natural field conditions. Out of 113 BC 2 F 1 plants of cross (In3*Gemmiza12), 41 were positive for PmTb7A.1 linked markers, while 13 were positive for PmTb7A.2 linked markers, 5 plants were positive for markers linked to both PM resistance genes and 54 plants did not show any introgression. Analysis with Sr22 gene linked marker showed introgression in 41 plants of cross (In3*Gemmiza12). Thus, most of the lines with PmTb7A.1 carried Sr22 and were resistant to stem rust in the field trials.