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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 F8 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

Bread-making quality is a core trait for wheat breeding programs. Recently, the expression of a novel gene named wheat bread making (wbm) gene has been associated with good bread-making quality. In this study, 54 historical and modern bread wheat genotypes from CIMMYT were screened by PCR marker for the presence of the allele associated with high wbm expression. Eight of the 54 wheat genotypes tested positive for the wbm allele and the genotype Waxwing was identified as the most likely donor of the allele in part of CIMMYT germplasm. The wbm allele had a significant effect on overall gluten quality, gluten strength, gluten extensibility and bread-making quality, although its effect was smaller than the effects of other quality related genes as Glu-D1, Glu-B1 or the negative effect of the 1BL.1RS translocation. The wbm allele was associated with higher values of the traits mentioned but not with higher protein content. The identification of this new wbm gene/protein is a step forward in understanding wheat quality genetic control. Implementation of marker assisted selection in breeding programs to detect the wbm allele is highly recommended.

Leaf senescence is an important trait for yield improvement under stress. In the present study, 207 F2:4 random inbred lines (RILs) derived from the Jingdong 8/Aikang 58 cross were investigated under limited and full irrigation environments at two locations during the 2011–2012 and 2012–2013 cropping seasons. The RILs were genotyped with 149 SSR markers and QTLs for leaf senescence-related traits and heading dates (HD) were analyzed by inclusive composite interval mapping. The broad sense heritabilities of normalized difference vegetation index at Zadoks47 (NDVIv) and at Zadoks75 (NDVIg), leaf senescence rate (LSR), leaf senescence scored visually (LSS), leaf area index (LAI) and HD were 0.37–0.54, 0.39–0.48, 0.4–0.45, 0.56–0.58, 0.64–0.79 and 0.82–0.86, respectively. There were significant correlations between NDVIg and LSR (r = −0.55 to −0.70), NDVIg and LSS (r = −0.61 to −0.61), and LSS and LSR (r = 0.48–0.68). NDVIv and LAIv explained 18.5 % and 19.4 % of the variation in grain yield under limited irrigation, respectively. Forty five QTLs were distributed on 15 chromosomes. The respective numbers of QTLs for NDVIv, NDVIg, LSR, LSS and HD were 10, 10, 9, 9 and 7 across all eight environments. Previously unreported QTLs were found on chromosomes 1A, 2D, 5B, 7A and 7D for NDVI, on 6D for LSR and 5B for LSS. QNDVIv.caas-4A explained 23.7–56.6 % of the phenotypic variation (PV) for NDVIv and was stably expressed in four environments. In contrast, QNDVIg.caas-4B.2 explained 13.2–16.0 % of PV but was only expressed in full irrigation. Pleiotropic QTLs were detected; QNDVIv.caas-5B, explaining 22.9–35.9 % of PV, had an effect on LSS, and QNDVIg.caas-4D, accounting for 11.5–28.5 % of PV, also influenced NDVIv. QTLs controlling LSR, QLSR.caas-4D and QLSR.caas-3B, also increased thousand kernel weight and grain yield, indicating that rapid senescence increased grain filling rate. Some QTLs such as QNDVIg.caas-1A.1, QLSR.caas-2A, QLSS.caas-2B, QLSS.caas-3B, QLSS.caas-5B and QLSS.caas-2D.1 were detected only under limited irrigation. These drought stress-induced QTLs could be valuable for improving drought resistance in wheat.

Seedling vigor is an important trait characterized by rapid development of vegetative cover above the soil surface, particularly in rainfed environments. To elucidate the genetic basis of seedling vigor, 207 F2:4 lines derived from Jingdong 8/Aikang 58 were investigated in the field at Beijing and Gaoyi, Hebei province, during the 2011–2012 and 2012–2013 cropping seasons. A total of 148 SSR markers polymorphic between the parents, and the RhtD1b-specific marker were used to map QTL for seedling vigor by inclusive composite interval mapping (ICIM). Normalized difference vegetation index (NDVI) and ground cover (GC) before winter and in late spring showed a continuous distribution. Significant differences in NDVI and GC among lines were detected. Broad-sense heritability of NDVI and GC ranged from 0.69 to 0.74 based on the mean values averaged across four environments. GC was highly correlated with NDVI (r = 0.74–0.85, P

Pre-harvest sprouting (PHS) of wheat greatly reduces the quality and economic value of grain, and PHS resistance is one of the most important traits in wheat breeding. Red-grained wheat varieties are generally more resistant to PHS than white-grained ones; however, some are still susceptible. The red pigment of red-grained wheat is synthesized through the flavonoid biosynthetic pathway, in which the dihydroflavonol-4-reductase gene (DFR) is one of the genes involved in anthocyanin synthesis. In this study, a set of 120 red-grained Chinese wheat cultivars and lines with distinct PHS resistance were used to characterize TaDFR genotype variations and their association with PHS resistance. Whereas no variation or functional variation of TaDFR genes was detected on chromosomes 3A and 3D, a novel TaDFR allele, designated TaDFR-Bb, was explored on chromosome 3B. Compared with TaDFR-Ba, an 8 bp insertion (CTCTAGGA) was identified in the promoter region of TaDFR-B in most of the PHS resistant red-grained wheat varieties and advanced lines. Based on this, a CAPS marker was designed and validated with a set of Chinese red-grained wheat cultivars and lines with distinct PHS resistance. In most cases, TaDFR-Bb was associated with higher PHS resistance. An association study indicated that wheat varieties with the 8 bp insertion (average seed germination index 23.6 %) were significantly more resistant (P < 0.01) to PHS than those without the insertion (average seed germination index 69.5 %). Further study on gene expression demonstrated that the insertion led to increased TaDFR-B expression in cultivars with PHS resistance. Transient expression of TaDFR-B in coleoptiles of wheat cv. Chinese Spring revealed that increasing TaDFR gene expression did not induce the synthesis of anthocyanins.

Improvement of flour colour is an important breeding objective for various wheat-based end-products. The objectives of this study were to identify quantitative trait loci (QTL) for flour colour components and yellow pigment content (YPC), using 240 recombinant inbred lines (RILs) derived from a cross between the Chinese wheat cultivars PH82-2 and Neixiang 188. Field trials were performed in a Latinized α-lattice design in Anyang and Jiaozuo, Henan Province and Taian, Shandong, in the 2005–2006 and 2006–2007 cropping seasons providing data for six environments. One hundred and eighty-eight polymorphic SSR markers, rye secalin marker Sec1, STS markers YP7A for a phytoene synthase gene (Psy-A1), and four glutenin subunit markers, were used to genotype the population and construct the linkage map for subsequent QTL analysis. Two major QTL were detected for YPC, associated with 1RS (1B.1R translocation) and the Psy-A1 (7A) gene, explaining 31.9% and 33.9% of the phenotypic variances, respectively. 1RS also had large influences on Fa*, Fb*, KJ, NL*and Nb*, and Psy-A1 genes showed large effects on Fa*, Fb*, Kj, Fci, NL*, Na* and Nb*, explaining from 4.5 to 26.1% and 4.3 to 35.9% of the phenotypic variances, respectively. In addition, QTL for flour colour parameters and yellow pigment content were also detected on chromosomes 1A and 4A, accounting for 1.5–4.1% of the phenotypic variance. The genetic effect of the 1B.1R translocation on flour colour parameters was also discussed.