Monday, November 5, 2007 - 10:15 AM
79-5
Mapping QTLs for Pre-Harvest Sprouting Resistance in a U.S. White Winter Wheat.
Pre-harvesting sprouting (PHS) is a major constraint for wheat production in many wheat growing areas worldwide. Severe PHS not only reduces the end-use quality of wheat, but also causes substantial yield losses. An U.S. white winter wheat cultivar Rioblanco has demonstrated a high level of resistance to PHS, but its genetic mechanism of PHS resistance remains unknown. In this study, a population of recombinant inbred lines (RILs) was constructed by crossing RioBlanco to a PHS-susceptible line NW97S186. PHS of 170 F6 RILs was evaluated by incubating physiologically matured spikes in a moist chamber with 100% humidity. The experiment was repeated once with two replications in the greenhouse conditions. After 1430 SSR primer pairs were screened, 124 primers were polymorphic between the parents and between the resistant and susceptible bulks and used to screen the population. Three QTLs in Rioblance were detected for PHS resistance. One QTL with the largest effect on PHS resistance, designed as QPhs.rio-3A.1, was flanked by markers Xbarc57 and Xbarc12 in the distal region of 3AS and explained 20% to 41% of the total phenotypic variation in two greenhouse experiments. This QTL was validated in another population from RioBlanco/ NW97S078. In addition, two minor QTLs, designed as QPhs.rio-5B.2 on 5B and QPhs.rio-5d.3 on 2B, were flanked by markers Xgwm371 and Xgwm133-1, and Gwm132-1 and Dup398, respectively, and explained 10.8% to 16.9%, 10.4% to 19.6% phenotypic variations, respectively. The linked SSR markers to the QTLs have potential to be used for high-throughput marker-assisted selection for PHS-resistant wheat cultivars.
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