Breeding Of Near-isogenic Lines For Wheat High Molecular Weight Glutenin Subunits And Quality Effects Of Some Subunits

Wheat kernel protein can be divided into albumin, globulin, gliadin and glutenin. As themain component of glutens, gliadin and glutenin formed a complex polymer which controlsthe extensibility and extension resistance of dough. High molecular weight subunits(HMW-GS) only account for10%of the total amount of glutens, but plays a "networkskeleton" effect in the glutens structure and has significant effects on its function and wheatprocessing quality. Therefore, to clear the quality effect of HMW-GS is beneficial to discoverthe genetic potential and improve the processing quality of wheat. But, the present researchresults were not clear due to the interference of different genetic background and some otherfactors. So studying the quality effects of HMW-GS with Near-isogenic lines can waken theinterference caused by genetic background to the lowest level and making the results moreaccurate and credible, Therefore, the breeding of Near-isogenic lines has became theprecondition of relevant study, but the breeding process requires consective backcross andtracking detection costing a longer period, so the optimizing of subunits identification wouldaccelerate the breeding dramatically. This study is just base on the conditon mentioned above.Firstly, chosing six widely planted cultivars in the Huang-Huai wheat region and twointroduced cultivars from franch with high quality subunits as the recurrent parents and donorrespectively to transfer HMW-GS near-isogenic lines (NILs) through continuous backcrossand selfing, meanwhile, optimizing the test method of HMW-GS during the breeding process;secondly, studying the difference of the quality effects bettween the subunits5+10and2+12(encoded by Glu-D1),7+8and7+9(encoded by Glu-B1),2*and N (encoded by Glu-A1) byusing the BC₄F₃pure lines selected form the backcross generations. The main results for thisstudy are as follows:The former SDS-PAGE method was optimized in the progress of HMW-GSidentification of the backcross generations, meanwhile three multiple PCR systems used inthe identification of HMW-GS were developed based on the relevant single PCR; the identification of HMW-GS became more efficient and accurate after the SDS-PAGE andmolecular marker used together and19BC₄F₃pure lines from414backcross generationswere selected. Specifically, two NILs of the subunits5+10in the genetic background ofXiaoyan6, besides, one, one and three NILs of2*,7+8and5+10in the background ofXianyan22respectively, moreover, five NILs of5+10in the background of Xinong2208andsix NILs of5+10under the background of Xinong1718. Finally,17NILs under the lastgenetic background above were chosed as the materials of the quality effects researchfollowed.The research results of quality effects from different subunits showed that, at the Glu-D1loci, there is no difference of protein content between subunits5+10and2+12, comparingwith2+12,5+10has a better dough strength and extensibility resistentce, but the extensibilitydecreased slightly; in all the quality properties that were influenced significantly by the5+10,the Thousand Kernel Weight, brightness and red degrees of grain, sedimentation value, waterabsorption, stability time and softness were not influenced by the genetic background, but allthe other quality properties were influenced by the genetic background more or less; at theGlu-B1loci, the quality effects to the kernel color, flout color and farinograph parameters thatcaused by subunits7+8and7+9were influenced by the subunits composition of locus Glu-A1and Glu-D1; all the protein quality parameters of7+8were better than7+9and the relativechange degree was influenced by the subunits composition of the other two locus too; besides,comparing to subunits7+9, the7+8has a lower extensibility resistentce but a higherextensibility, meanwhile, its bread volume and bread score were poor than the latter. At theGlu-A1loci, comparing with the subunits N, the flour yield, flour red degree, flout yellowdegree and protein content of2*all increased; its mixing properties became poor andextensibility resistance increased dramatically with the decreased of extensibility, besides, thebread volume and bread score of2*were significantly better than N.This research chose six widely planted cultivars in the Huang-Huai wheat region as therecurrent parents to transfer HMW-GS NILs for the first time, the identification method ofHMW-GS was optimized and three multiple PCR systems were developed during theselecting progress. Finally,19BC₄F₃pure lines were selected from the backcross generationsand the quality effects of some subunits were studied using17lines of them, its results wouldprovide reference for the wheat quality breeding, cultivation and food processing.