Quantitative trait loci mapping of resistance to pre-harvest sprouting in the Norwegian spring wheat breeding line T7347

Sammendrag

Pre-harvest sprouting (PHS) can result in downgrading of food quality wheat to feed in seasons with high humidity and precipitation before harvest. Higher temperatures during the grain filling phase further reduce the dormancy level and increase the risk of PHS. However, some genotypes, including the Norwegian breeding line T7347, show a high level of dormancy even under elevated temperatures. In this study, the main objective was to investigate the genetic mechanisms behind the high dormancy in T7347. A population of 233 recombinant inbred lines was developed by crossing T7347 with Saar, a CIMMYT line with moderate to low level of dormancy. The population was grown in a total of 13 field trials at three different locations in Norway and Chengdu, China, and screened for germination index (GI) and falling number (FN). The population was genotyped with the TraitGenetics 25 K SNP chip, and QTL interval mapping revealed five stable PHS QTL on chromosomes 1A, 3A, 3B, 7A and 7B. Among these, the largest proportion of phenotypic variation of GI and FN was explained by QTL overlapping with the known red color loci on chromosomes 3AL and 3BL, with the alleles conferring dormancy contributed by T7347 and Saar, respectively. Additionally, two unique FN QTL were identified, on 4B overlapping with semi-dwarfing gene Rht-B1, and on 5AL co-located with the Tipped 1 awn locus. The effect of four of the PHS QTL and the two FN QTL could be validated in independent panels of advanced breeding lines.