QTL mapping of preharvest sprouting resistance in bread wheat population SHA3/CBRD by Naxos confirms a negative effect of the 1BL.1RS translocation on falling number

Summary

Preharvest sprouting (PHS) is a serious problem in wheat (Triticum aestivum L.)production areas with rainy harvest conditions. To explore the genetic control ofPHS resistance, a population of 166 recombinant inbred lines from a cross betweenSHA3/CBRD and Naxos was evaluated in a total of eight field trials in Norway andChina. PHS resistance was evaluated with both germination index (GI) and fallingnumber (FN). A total of 15 PHS-related quantitative trait loci (QTLs) were detected atchromosome arms 1RS, 2DL, 3BL, 4AL, 4BS, and 7BL. At 2DL and 3BL, QTLs forboth GI and FN were detected in proximity to each other with PHS resistance fromSHA3/CBRD, indicating a common genetic control of the two traits at these loci.At 4AL, a significant QTL for GI was detected with seed dormancy contributed byNaxos. Moreover, the Rht-B1b dwarfing allele contributed by SHA3/CBRD showeda positive association with FN. On the other hand, QFN.nmbu-1RS, carried by the1BL.1RS translocation in SHA3/CBRD showed consistent negative effects on FNacross all field trials where FN was measured. However, it did not have any notableeffect on GI. The negative effect of QFN.nmbu-1RS on FN was validated on a set of113 wheat cultivars and breeding lines, where lines carrying the 1BL.1RS translo-cation showed significantly lower FN in 12 out of 14 independent field trials. TheQTL and associated markers identified in this study will aid the breeding of morePHS-resistant wheat cultivars.