Conditional QTL Analysis Of Interaction Between Wheat Protein And Starch Content

Wheat, one of important food crops, is widely grown all over the world. It is not a nativein our country, but imported from a remote outland around5000years ago. Many importantagronomic traits and quality traits (e.g., yield traits, protein content, resistance, etc.) arecontrolled by multiple genes. So, it is very important for improving wheat quality byanalyzing quantitative traits loci (QTL). Conditional QTL mapping have been studied inrecent years. It can dissect not only the dynamic expression of QTL under differentenvironments or different periods of development, but dissect the QTL interactions betweenrelated traits. This would prepare gene resources for molecular marker assisted breeding andmolecular aggregation breeding, and can also lay a foundation for fine mapping and cloningof related genes.Therefore unconditional and conditional QTL mapping was conducted on the grainprotein, flour protein and starch content using three different genetic populations underdifferent environments in this research. The results were as follows:1. QTL for grain protein contentOn the basis of the three wheat genetic groups and their corresponding genetic linkagemaps, QTLs for GPC was evaluated in the four different environments by using the softwareof QTLNetwork2.0based on the mixed linear model approach.13unconditional and13conditional additive QTLs were detected. QGPC2A-12、QGPC6D-13（DH Population）、QGPC1D-15（RIL1Population）、QGPC2D-23、QGPC2D-31（RIL2Population）are detectedin both two methods, so these five QTLs belong to the independent expression of QTL. Thereare10pairs of epistatic unconditional QTLs and8pairs of epistatic conditional QTLs Most of them were minor QTLs. Only QGPC3B-6/QGPC4D detected in the two methods belonged tothe major QTL with phenotypic variance greater than10%.2. QTL for grain starch content7unconditional (two major) and9conditional additive QTLs (two major) for GSC weredetected. QGSC1D-1、QGSC4A-9、QGSC7B-15and QGSC7D-2were found simultaneouslyin the two methods, which indicated that this four QTLs could be expressed independenly.QGSC7B-15could account for phenotypic variance20.79%and21.51%, respectively. Thereare4pairs of epistatic unconditional QTLs and9pairs of epistatic conditional QTLs.Although the phenotypic variance of each of them showed be less than5%, the epistatic effectof accumulation cannot be ignored.3. QTL for starch componentsStarch composition is not only affected by the additive effect but epistatic effect. Thecontribution of additive is greater than that of epistatic effect There was one QTL located inthe chromosome4A, which influenced the flour starch content by affecting amylose content.In addition, other QTLs we found which influenced flour starch content by amylase oramylopectin content, are affected by another component in the different degree.4. QTL for protein componentsThere were11additive QTLs (two major QTL) of protein components with thephenotypic variance from4.23%and26.34%. Twenty two pairs of epistatic QTLs of proteincomponents can be found with the phenotypic variance from10.08%and28.79%.