Molecular cytogenetic characterization of wheat- Aegilops umbellulata leaf rust and stripe rust resistant introgression lines
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Date
2011
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PAU Ludhiana
Abstract
Leaf rust and stripe rust are the most damaging diseases of wheat. Ae. umbellulata, was found to be an excellent source of resistance for various diseases. In the present investigation, characterization of the WL711-Ae. umbellulata introgression lines (ILs) through Genomic in situ hybridization to determine the size of the alien segment and Bulked Segregant Analysis (BSA) for tagging of stripe rust and leaf rust resistance genes introgressed from Ae. umbellulata into Triticum aestivum were undertaken. GISH showed the presence of complete Ae. umbellulata chromosome in ILs T311-5 and T315-5 whereas no hybridization signal was detected in other ILs. BC2F4 population derived from the cross of introgression line T393-4 with PBW343 segregated for a leaf rust (103R:66H:77S; 2=4.102) and a stripe rust resistance gene (108R:64H:74S; 2=6.401). The progeny testing in BC2F5 confirmed the transfer of a single gene for leaf rust resistance. BSA using 31 polymorphic markers indicated the association of short arm of chromosome 5D with rust resistance. The 5DS mapped SSR markers Xgwm190 and Xwmc805 detected parental IL specific alleles in resistant bulk. In order to distinguish the leaf rust and stripe rust resistance gene transferred from Ae. umbellulata (LrU and YrU) from previously mapped Lr57/Yr40 at same location, the Lr57/Yr40 CAPS primer was amplified and the amplicons were sequenced. A number of SNPs were detected which could distinguish two introgressions carrying Lr57/Yr40 and LrU/YrU. Linkage mapping using computer software MapDisto mapped leaf rust gene on 5DS with Lr57/Yr40 CAPS marker at a distance of 2.5cM. Stripe rust resistance gene mapped towards the distal end of 5DS at a distance of 4.1cM from the LrU. LrU/YrU carrying alien introgression was further distinguished from Lr57/Yr40 introgression, through the identification of SNPs in the grain softness protein specific amplicons. The LrU and YrU are proposed to be putatively new genes which provide complete resistance against leaf rust and stripe rust, respectively.
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