Micronutrient malnutrition affects over three billion people worldwide, especially women and children in developing countries. Increasing the bioavailable concentrations of essential elements in the edible portions of crops is an effective resolution to address this issue. To determine the genetic factors controlling micronutrient concentration in wheat, the quantitative trait locus （QTL） analysis for iron, zinc, copper, manganese, and selenium concentrations in two recombinant inbred line populations was performed. In all, 39 QTLs for ifve micronutrient concentrations were identiifed in this study. Of these, 22 alleles from synthetic wheat SHW-L1 and seven alleles from the progeny line of the synthetic wheat Chuanmai 42 showed an increase in micronutrient concentrations. Five QTLs on chromosomes 2A, 3D, 4D, and 5B found in both the populations showed signiifcant phenotypic variation for 2-3 micronutrient concentrations. Our results might help understand the genetic control of micronutrient concentration and allow the utilization of genetic resources of synthetic hexaploid wheat for improving micronutrient efifciency of cultivated wheat by using molecular marker-assisted selection.
Starch is the major carbohydrate in oat （Avena sativa L.） and starch formation requires the coordinated actions of several synthesis enzymes. In this study, the granule morphology, composition and physicochemical properties of oat starch, as well as the expressions of starch synthesis genes were investigated during oat endosperm development. Under the scanning electron microscopy （SEM）, we observed that the unique compound granules were developed in oat endosperms at 10 days post anthesis （DPA） and then fragmented into irregular or polygonal simple granules from 12 DPA until seed maturity. The amylose content, branch chain length of degree of polymerization （DP=13-24）, gelatinization temperature and percentage of retrogradation were gradually increased during the endosperm development; whereas the distribution of short chains （DP=6-12） were gradually decreased. The relative expressions of 4 classes of 13 starch synthesis genes characterized in this study indicated that three expression pattern groups were significantly different among gene classes as well as among varied isoforms, in which the first group of starch synthesis genes may play a key role on the initiation of starch synthesis in oat endosperms.
γ-Gliadins are an important component of wheat seed storage proteins. Four novel γ-gliadin genes （Gli-ngl to Gli-ng4） were cloned from wheat （Triticum aestivum） and Aegilops species. The novel γ-gliadins were much smaller in molecular size when compared to the typical γ-gliadins, which was caused by deletion of the non-repetitive domain, glutamine-rich region, 3＂ part of the repetitive domain, and 5＇ part of the C-terminal, possibly due to illegitimate recombination between the repetitive domain and the C-terminal. As a result, Gli-ngl and Gli-ng4 only contained two and three cysteine residues, respectively. Gli-ngl, as the representative of novel γ-gliadin genes, has been sub-cloned into an Escherichia coli expression system. SDS- PAGE indicated that the both cysteine residues of Gli-ngl could participate in the formation of intermolecular disulphide bonds in vitro. Successful cloning of Gli-ngl from seed cDNA of T. aestivum cv. Chinese Spring suggested that these novel γ-gliadin genes were normally transcribed during the development of seeds. Phylogenic analysis indicated that the four novel γ-gliadin genes had a closer relationship with those from the B （S） genome of wheat.
Aegiliops tauschii is classified into two subspecies： Ae. tauschii ssp. tauschii and Ae. tauschii ssp. strangulata. Novel genetic variations exist in Ae. tauschii ssp. tauschii that can be utilized in wheat improvement. We synthesized a hexaploid wheat genotype（SHW-L1） by crossing an Ae. tauschii ssp. tauschii accession（AS60） with a tetraploid wheat genotype（AS2255）. A population consisting of 171 F8 recombinant inbred lines was developed from SHW-L1 and Chuanmai 32 to identify QTLs associated with agronomic traits. A new genetic map with high density was constructed and used to detect the QTLs for heading date, kernel width, spike length, spikelet number, and thousand kernel weight. A total of 30 putative QTLs were identified for five investigated traits. Thirteen QTLs were located on D genomes of SHW-L1, six of them showed positive effect on agronomic traits. Chromosome region flanked by wPt-6133–wPt-8134 on 2D carried five environment-independent QTLs. Each QTL accounted for more than 10% phenotypic variance. These QTLs were highly consistent across environments and should be used in wheat breeding.
Waterlogging is a widespread limiting factor for wheat production throughout the world. To identify quantitative trait loci （QTLs） associated with waterlogging tolerance at early stages of growth, survival rate （SR）, germination rate index （GRI）, leaf chlorophyll content index （CCI）, root length index （RLI）, plant height index （PHI）, root dry weight index （RDWI）, shoot dry weight index （SDWI）, and total dry weight index （DWI） were assessed using the International Triticeae Mapping Initiative （ITMI） population W7984/Opata85. Significant and positive correlations were detected for all traits in this population except RLI. A total of 32 QTLs were associated with waterlogging tolerance on all chromosomes except 3A, 3D, 4B, 5A, 5D, 6A, and 6D. Some of the QTLs explained large proportions of the phenotypic variance. One of these is the QTL for GRI on 7A, which explained 23.92% of the phenotypic variation. Of them, 22 alleles from the synthetic hexaploid wheat W7984 contributed positively. These results suggested that synthetic hexaploid wheat W7984 is an important genetic resource for waterlogging tolerance in wheat. These alleles conferring waterlogging tolerance at early stages of growth in wheat could be utilized in wheat breeding for improving waterlogging tolerance.
