CYTOGENETIC CHARACTERIZATION AND MOLECULAR TAGGING OF LEAF RUST RESISTANCE GENE TRANSFERRED FROM Aegilops peregrina INTO HEXAPLOID WHEAT
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Date
2012
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PAU Ludhiana
Abstract
Leaf rust is the most damaging disease of wheat worldwide. Wild germplasm of wheat is known to be a rich source of different useful genes. Ae. peregrina acc. pau 3519, a non-progenitor tetraploid species with UUSS genome, was found to be an excellent source of resistance for various diseases. In the present investigation, WL711-Ae. peregrina introgression lines (ILs) were characterized through Genomic in situ hybridization and no hybridization signal was detected in any of the IL. F2 population derived from the cross of introgression line 973 with WL711, was tested at seedling stage and segregated in a ratio of 191 resistant:63 susceptible plants with 2=0.0052(3:1). At the adult plant stage, the population segregated into 185 resistant: 65 susceptible with 2=0.0053(3:1). The progeny testing in F3 confirmed the transfer of a single gene for leaf rust resistance. Molecular characterization of the IL973 with the SSR markers indicated Ae. peregrina specific introgression on homoeologous groups 1, 2, 5 and 7. Bulked segregant analysis was done using 79 polymorphic markers and one of the SSR marker Xcfd50, detected IL973 specific allele in resistant bulk. This marker has already been reported to be linked with known gene Lr58 from Ae. triuncialis on long arm of chromosome 2B. STS marker Xncw-Lr58 amplified on whole F2 population and it was mapped at a distance of 1.7 cM from leaf rust resistance gene using computer software MapDisto. Nullitetrasomic analysis confirmed the introgression of Ae. peregrina leaf rust resistance gene (LrAP) on the wheat chromosome 2D. LrAP gene studied during the present investigation is either a new gene or an allele of the already known gene Lr58 will be established through allelic tests in subsequent studies.
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