Cloning and Characterization of a QTL for Pre-Harvest Sprouting (PHS) Resistance in White Wheat.

Pre-harvest sprouting (PHS) affecting both grain yield and quality is one of the major problems for wheat production worldwide. We previously mapped one major QTL, QPhs.pseru-3AS, for PHS resistance in a white wheat cultivar Rio Blanco. In the current study, we fine mapped and cloned this QTL using a comparative mapping, association analysis and RNA interference. A physical map of the QTL region was constructed. Sequencing the BACs covering the QTL region identified a candidate gene for QPhs.pseru-3AS, designated TaPHS1. This gene is highly expressed during seed development and sprouting process. It functions as a positive regulator for PHS resistance. Transgenic Bobwhite (PHS resistant cultivar) plants with the RNAi construct became highly PHS susceptible, confirming that loss of function of TaPHS1 is responsible for PHS susceptibility. The variations of this gene in diverse wheat cultivars were also studied. Cloning of this gene provide opportunities for a more comprehensive understanding of seed development and sprouting in wheat.