QTL mapping for plant height and yield components in common wheat under water-limited and full irrigation environments

Plant height (PH) and yield components are important traits for yield improvement in wheat breeding. In this study, 207F(2:4) recombinant inbred lines (RILs) derived from the cross Jingdong 8/Aikang 58 were investigated under limited and full irrigation environments at Beijing and Gaoyi, Hebei province, during the 2011-12 and 2012-13 cropping seasons. The RILs were genotyped with 149 polymorphic simple sequence repeat (SSR) markers, and quantitative trait loci (QTLs) for PH and yield components were analysed by inclusive composite interval mapping. All traits in the experiment showed significant genetic variation and interaction with environments. The range of broad-sense heritabilities of PH, 1000-kernel weight (TKW), number of kernels per spike (KNS), number of spikes per m(2) (NS), and grain yield (GY) were 0.97-0.97, 0.87-0.89, 0.59-0.61, 0.58-0.68, and 0.23-0.48. The numbers of QTLs detected for PH, TKW, KNS, NS, and GY were 3, 10, 8, 7 and 9, respectively, across all eight environments. PH QTLs on chromosomes 4D and 6A, explaining 61.3-80.2% of the phenotypic variation, were stably expressed in all environments. QPH.caas-4D is assumed to be the Rht-D1b locus, whereas QPH.caas-6A is likely to be a newly discovered gene. The allele from Aikang 58 at QPH.caas-4D reduced PH by 11.5-18.2% and TKW by 2.6-3.8%; however, KNS increased (1.2-3.7%) as did NS (2.8-4.1%). The QPH.caas-6A allele from Aikang 58 reduced PH by 8.0-11.5% and TKW by 6.9-8.5%, whereas KNS increased by 1.2-3.6% and NS by 0.9-4.5%. Genotypes carrying both QPH.caas-4D and QPH.caas-6A alleles from Aikang 58 showed reduced PH by 28.6-30.6%, simultaneously reducing TKW (13.8-15.2%) and increasing KNS (3.4-4.9%) and NS (6.5-10%). QTKW.caas-4B and QTKW.caas-5B.1 were stably detected and significantly associated with either KNS or NS. Major KNS QTLs QKNS.caas-4B and QKNS.caas-5B.1 and the GY QTL QGY.caas-3B.2 were detected only in water-limited environments. The major TKW QTKW.caas-6D had no significant effect on either KNS or NS and it could have potential for improving yield.