Mapping And Meta-analysising Of QTLs For Plant Height And Thousand-grain Weight In Wheat

Plant height and grain weight were important agronomic traits that affect wheat(Triticum aestivum L) yield, and reasonable height and grain weight were high the premise to obtain high grain yield. However, plant height, grain weight and other production-related factors will be reduced in wheat under drought stress condition, to alleviate injury of drought stress on the plant body, maximize to maintain survival and produce offspring. And they showed significant flexible adaptation to water and low heritability, highlighted complicated genetic quantitative characteristics, which brings greater difficulties for wheat plant height and grain weight drought-resistant and conventional breeding. Therefore, using quantitative genetics and meta-analysising to analyze genetic basis for plant height and grain weight drought-resistant, to explore major QTL and candidate molecular markers, and these will be have great significance to improve drought resistance genetic improvement efficiency and accuracy of wheat plant height and grain weight. So in this study, A total of 120 recombinant inbred lines( RIL) derived from Chinese winter wheat cultivars Longjian 19×Q9086 and the two parents were taken as test materials, Setting different water environment, to do the QTL mapping and molecular quantitative genetic analysis for wheat plant height and grain weight; then integrate QTL information and carry out meta-analysising. The results are as follows:1. Plant height and grain weight of wheat RIL population were significantly sensitive to water conditions and showed wide variations and transgressive segregations. And they were complex quantitative traits controlled by polygenes and susceptible to water environment.2. Nineteen additive QTLs(A-QTLs) and 45 epistatic QTLs(AA-QTLs) for PH were identified and widely distributed on all chromosomes besides 3D. The expression of these QTLs might influence the phenotypic variation of PH by the up- and down-regulation, accounted for variations of PH by 0.47%~7.14%and 0.34%~2.93%, respectively. Two A-QTLs, Qph.acs-5A.1 and Qph.acs-7A.1, could be detected in multi-environments. In addition, two A-QTL hot-spot regions for PH were also found in some specific intervals, e.g., Xbarc1072-XBarc167 on chromosome 2B and Xksum253-Xbarc164 on chromosome 5B. Most of interaction effects of A-QTLs and AA-QTLs with drought-stressed environments showed the down-regulation for the PH variations. The additive and the epistatic effect could be main genetic factors controlled the PH inheritance, which expressions might decrease PH.3. 19 additive QTLs(A-QTLs) and 38 pairs of epistatic QTL(AA-QTLs) were detected for TGW in wheat, distributed on all chromosomes besides 1A, 3B, 4D and 6A. Expression of these QTLs might influence the phenotypic variation of TGW by the up- and down-regulation, which accounted for variations of TGW by 1.24%~10.94% and 0.38%~2.89%, respectively. Three A-QTLs, Qtgw.acs-1B.1, Qtgw.acs-2A.1 and Qtgw.acs-4A.1, could be detected in multi-environments. In addition, four A-QTL hot-spot regions for TGW were also found in some specific intervals, e.g., Xmag2064-Xbarc181 on chromosome 1B, Xwmc522-Xgwn122 on chromosome 2A, Xwmc446-Xgwm610 on chromosome 4A and Xwmc603-Xbarc195 on chromosome 7A. Most of interaction effects of A-QTLs and AA-QTLs with drought-stressed environments showed the down-regulation for the TGW variations. The additive and the additive×environment interaction effect could be main genetic factors controlled the TGW inheritance, which expressions might decrease TGW.4. Total of 177 QTLs for PH and 134 QTLs for TGW were integratied from previous mapped data. Through the Meta-analysis, 28 of MQTLs for PH and 21 MQTLs for TGW were identified, distributed on chromosome 1A, 1D, 2A, 3A, 5A, 5D, 7A, 7B and 1D, 2A, 3A, 3B, 3D, 5A, 7A, 7B, respectively. Each chromosome averagely contained 3.5 MQTLs for PH and 2.6 MQTLs for TGW, respectively. But the distribution of MQTLs was enriched and cluster on the specific intervals of chromosomes. Among them, the marker interval Xgwm96-Xwmc795 on chromosome 1A, Xgwm96-Xwmc795 on chromosome 5A, Xwmc434b-vrnd on chromosome 5D, Xwmc828-Xfba234 on chromosome7 A were MQTL hotspots for PH. The marker interval Xcfp7-Eactg.Mctc.1 on chromosome 3B, Xcfd9-Xfbb269 on chromosome 3D, Xmag747-Xfba382 a on chromosome 7A were the MQTL hotspots for TGW. It indicated that many important genes controlled the PH and TGW could locate on these key marker intervals. The 7A chromosome was the main cluster area of MQTLs for PH and TGW, on which were located in the same or overlapping area especially on Xmag747-Xfba382 a. It indicated that it could exist "pleiotropism" sites.