Genome-wide linkage mapping of QTL for physiological traits in a Chinese wheat population using the 90K SNP array

Many physiological traits are associated with grain yield and yield-related traits in wheat. The aim of the present study was to identify quantitative trait loci (QTL) for physiological traits, including ground cover, normalized difference in vegetation index and canopy temperature depression, and closely linked molecular markers for marker-assisted breeding. Two hundred and forty-six F-8 recombinant inbred lines (RILs) come from the Zhou 8425B/Chinese Spring cross were genotyped using the high-density Illumina iSelect 90K single nucleotide polymorphism (SNP) assay. Field trials were conducted under irrigated conditions at Zhengzhou and Zhoukou in Henan province, during the 2012-2013 and 2013-2014 cropping seasons. Analysis of variance of physiological traits showed significant differences (P < 0.01) among RILs, and RILs x environment interactions. Ground cover at late spring (GC-S), normalized difference in vegetation index at late spring (NDVI-S), and ground cover pre-winter (GC-W), had moderate broad-sense heritabilities of 0.66, 0.52 and 0.40, respectively. GC-S, NDVI-S and canopy temperature depression at 10 days post anthesis (CTD-10) were positively correlated with GY. Using a high-density linkage map of 5636 polymorphic SNP markers and composite interval mapping, 24 QTL for GC, NDVI and CTD were identified on 12 chromosomes, explaining 3.4-14.6 % of the phenotypic variance. Five stable QTL were detected across three environments, viz. QGC-W.caas-7AL, QNDVI-S.caas-7AL, QGC-S.caas-3AS, QCTD-A.caas-5BS and QCTD-10.caas-5BS. In addition, 10 QTL clusters were observed on chromosomes 1AL, 2AL, 2BL, 3AS, 3B (2), 4BS, 5B, 7AS, and 7AL. The stable QTL and QTL clusters were linked to SNP markers, with genetic distances to the closest SNPs ranging from 0 to 2.0 cM; these could be used for marker-assisted selection to improve yield-related traits in wheat breeding.