Friday seminar on 27th November 2015:
Venue: RDC Yusipang.
The first aspect of this investigation covers QTL analysis of triple rust resistance segregating among W195/BT-Schomburgk Selection (BTSS) recombinant inbred line (RIL) population. Three QTL each for stripe rust (QYr.sun-3BS; QYr.sun-4DL; QYr.sun-7AS), leaf rust (QLr.sun-2BS; QLr.sun-3BS; QLr.sun-4DL) and stem rust (QSr.sun-2BL; QSr.sun-4DL; QSr.sun-6AS) resistance were identified. QYr.sun-3BS, QYr.sun-4DL, QLr.sun-4DL and QSr.sun-4DL were contributed by W195, whereas other QTL were contributed by the alternate parent BTSS.
QTL analysis was followed by detailed characterization of the resistance loci. QYr.sun-3BS explained 34-59% phenotypic variation and was chosen for characterisation at different growth stages and temperature regimes. It expressed well at the 4th leaf stage at a higher than normal temperature (21±2 ºC) for stripe rust growth. This locus was formally named Yr58. The co-located QTL for stripe rust, leaf rust and stem rust resistance in chromosome 4DL was demonstrated to correspond to the pleiotropic adult plant resistance (APR) locus Yr46/Lr67/Sr55 through linked marker genotyping. Yr58 produced infection type 23C when present singly and in the presence of Yr46 it produced infection type; 1N.These results demonstrated the interaction of APR gene Yr46in improving expression of the middle stage resistance gene Yr58. QLr.sun-2BS and QSr.sun-6AS were confirmed to be Lr23 and Sr8a, respectively,through seedling tests using relevant pathotypes. QYr.sun-7AS, QLr.sun-3BS, QSr.sun-2BL appear to be unique APR loci and need to be characterised in detail.
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