Ahmed Fawzy Elkot
Agricultural Research Center,Egypt
Title: Fine mapping and transfer of two Powdery mildew resistance genes PmTb7A.1 and PmTb7A.2 from Triticum boeoticum (Boiss.) to Triticum aestivum (L.)
Biography
Biography: Ahmed Fawzy Elkot
Abstract
Powdery mildew (PM), caused by Blumeria graminis f. sp. tritici, is one of the important wheat diseases, worldwide. Two PM resistance genes, designated as PmTb7A.1 and PmTb7A.2, were identified in T. boeoticum acc. pau5088 and mapped on chromosome 7AL approximately 48cM apart. Shotgun sequence assembly data for chromosome 7AL were utilised for fine mapping of these Pm resistance genes, two resistance genes analogue (RGA)-STS markers Ta7AL-4556232 and 7AL-4426363 were identified to be linked to the PmTb7A.1 and PmTb7A.2, at a distance of 0.6cM and 6.0cM, respectively. The two genes were transferred to T. aestivum using T. durum as bridging species. As many as 12,317 florets of F1 of the cross T. durum /T. boeoticum were pollinated with T. aestivum lines PBW343-IL and PBW621 to produce 61 and 65 seeds, respectively of three-way F1. The resulting F1s of the cross T. durum/T. boeoticum//T. aestivum, were screened with marker flanking both the PM resistance genes PmTb7A.1 and PmTb7A.2 (foreground selection) and the selected plants were backcrossed to generate BC1F1. Introgression of alien chromatin in BC2F1 plants varied from 15.4 - 62.9 per cent. Out of more than 110 BC2F1 plants showing introgression for markers linked to the two PM resistance genes, 40 agronomically desirable plants were selected for background selection.The BC2F2 plants homozygous for the two genes have been identified. The PM resistance gene PmTb7A.1 maps in a region very close Sr22, a stem rust resistance gene effective against the race Ug99. Analysis of selected plants with markers linked to Sr22 showed introgression of Sr22 from T. boeoticum in several BC2F1 plants. Thus, in addition to PM resistance these progeny might also carry resistance to stem rust race Ug99.