| Wheat biomass and yield are commonly limited by a lack of water essential for growth. Carbon isotope discrimination, through its negative relationship with water use efficiency, has been used in selection of higher wheat yields in breeding for rain-fed environment. Selection efficiency of carbon isotope discrimination would be enhanced with a better understanding of its genetic control. 128 RILs derived from the cross of common wheat(Triticum aestivum L.) Ningchun4 × Ningchun27 were used as the plant materials, QTL analysis of spring wheat carbon isotope discrimination and flag leaf traits were performed through whole genome scanning. Correlation analysis of flag leaf traits and carbon isotope discrimination were evaluated by SPSS. The results are as follows:1. Carbon isotope discrimination significantly negative correlated with flag leaf length(P<0.05), flag leaf width(P<0.01) and flag leaf area(P<0.01). Significant positive correlation were detected among flag leaf length, width and area(P<0.01). Flag leaf SPAD score showed a significant positive correlation with flag leaf length, width and area(P<0.01).2. A population of 128 F9 recombinant inbred lines(RILs) was developed from the cross Ningchun4×Ningchun27 by single-seed descent. The genetic linkage map which contained 291 SSR markers covered 21 pairs of wheat chromosomes with a total genetic distance of 2576.09 cM and an average marker interval of 8.85 cM.3. Four water treatment experiments showed that spring wheat performed low carbon isotope discrimination in drought environment. Carbon isotope discrimination raised with the increase of available water during wheat whole growth period. When the available water reached the threshold, carbon isotope discrimination reduced with the increase of available water. QTL analysis of carbon isotope discrimination was performed by ICIM method, 5 additive QTLs with PVE of 10.69%~47.54% and 4 epistatic QTLs with PVE of 16.06~40.34% were detected under 4 different water treatments. Both additive QTL and epistatic QTL interacted with environment, explained 1.48%~3.18% of the phenotypic variation. Spring wheat carbon isotope discrimination were equally controlled by additive effect and epistatic effect and interacted with environment.4. QTL analysis of flag leaf length, width, area, SPAD were performed by ICIM method in 3 different environments. 6 additive QTLs for flag leaf length, 8 additive QTLs for width and 5 additive QTLs for area were detected and explained 7.27%~28.66%, 5.93~18.33%, 10.00%~35.17% of phenotypic variation respectively. 16 QTLs interacted with environment, which can explain 0.18%~3.46% of phenotypic variation, indicated that flag leaf length, width and area were controlled by additive effect and interacted with environment. 4 additive QTLs with PVE of 8.54%~33.11% and 3 epistatic QTLs with PVE of 13.29%~14.12% were detected for flag leaf SPAD. Both additive QTL and epistatic QTL interacted with environment except for Qspad-3D/7B and Qspad-5B/7B, explained 0.30%~3.84% of the phenotypic variation. Flag leaf SPAD was mainly controlled by additive effect more than epistatic effect and interacted with environment.5. Four co-located intervals on chromosome 3B, 5D and 7B were detected. Flag leaf area QTL-Qfla-3B and flag leaf width QTL-Qflw-3B.1 located in barc164-gwm376 marker interval on chromosome 3B with genetic distance of 9.45 cM. Flag leaf area QTL-Qfla-7B.2 and flag leaf length QTL-Qfll-7B.2 located in gwm400-barc176 marker interval on chromosome 7B with genetic distance of 15.19 c M. Flag leaf width QTL-Qflw-5D, flag leaf length QTL-Qfll-5D and flag leaf area QTL-Qfla-5D.1 located in cfd67-cfd40 marker interval on chromosome 5D with genetic distance of 11.24 cM. Carbon isotope discrimination QTL-Qcid-7B, flag leaf length QTL-Qfll-7B.2, flag leaf width QTL-Qflw-7B and flag leaf area QTL-Qfla-7B.1 located in barc267-gwm46 on chromosome 7B with genetic distance of 1.45 cM, suggested that the chromosomal interval had pleiotropic QTL for different traits. |
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