Preharvest sprouting (PHS) in wheat is the untimely germination of mature seed on the mother plant before harvest that can destroy the baking quality. Hence, such wheat lots will be degraded to feed. Higher temperatures combined with high humidity between grain ripening and harvest decrease the dormancy level and promotes preharvest sprouting (PHS). However, some genotypes, including the Norwegian breeding line T7347, show a high level of dormancy even under elevated temperatures.

In this study, we investigated the genetic mechanisms behind the high dormancy in T7347. A population of 233 recombinant inbred lines (RILs) was developed by crossing T7347 with Saar, a CIMMYT line with moderate to low level of dormancy. The population was grown at three different locations in Norway and Chengdu, China in a total of 13 trials, and screened for germination index (GI) and falling number (FN). Red grain is known to be associated with higher level of dormancy than white grain, and we measured color with NIR-VIS on dry seeds.

The population was genotyped with the TraitGenetics 25 K SNP chip and QTL 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.

To further investigate genes underlying the QTL, a transcriptome study was carried out on a subset of extreme dormant and non-dormant RILs grown in the greenhouse. RNA was extracted from embryo, aleurone and starchy endosperm 30 days after anthesis. Transcriptome analysis allowed us to identify several candidate genes within the QTL regions. Current work includes establishment of a gene editing protocol for functional validation of these.