Genetic Analysis And QTL Of Agronomic Traits In Wheat

Seven agronomic traits, including plant height, effective tillers, spike length, spikeletsper spike, grains per spike, spike and flag leaf distance and compactness, are closely relatedto wheat yield. To study of the genetic law of these important agronomic traits, F₂and F₃populations which derived from wheat Xinong817and Chinese Spring were planted in theexperimental field of Northwest A&F University. Based on the constructed populations, twomethods were used to analysis the genetic law of those agronomic traits. One method is jointsegregation analysis of a mixed genetic model of major gene plus polygene in fivegenerations （P₁, P₂, F₁, F₂and F₃）, and the other is QTL mapping. Better understanding ofthese traits’s genetic law is significant to improve wheat yield, shorten breeding process. Theresults are as follows:1. Using the method of P₁, P₂, F₁, F₂, F₃five generation joint analysis, the best geneticmodels of plant height, effective tillers, spikelets per spike, spike length,grains per spike,spike and flag leaf distance and compactness were showed that the7agronomic traits werenot only controlled by the genes, but also impacted by environment. Among them, spikelength, grains per spike were totally controlled by polygenes without any major gene. Plantheight, spikelets per spike, compactness were controlled by a major gene and severalpolygenes, which all showed additive and dominant effect. Spike and flag leaf distance wascontrolled by a major gene with total dominant effect plus several polygenes with bothaddictive and dominant effect. Effective tillers was controlled by a major gene with negativeand completely dominant effect plus several additive-dominant polygenes.2.Base on comparison important agronomic traits, including plant height, effectivetillers, spikelets per spike, spike length, grains per spike, spike and flag leaf distance andcompactness, significant difference was found between wheat Xinong817and ChineseSpring.The range of variation among F₂and F₃populations in each trait was respective large.There were some individuals among F₂and F₃populations showed lower or higher than wheatXinong817and Chinese Spring. So this population was useful for QTL mapping.3.192lines in the F₃population were selected as the mapping population. DNA of Five plants which were selected randomly in each line were extracted together to represent theDNA of F₂population. A map consisting of131SRAP and SSR which showed differencebetween wheat Xinong817were constructed. The total length of the map was2268.46CM,and the average distance of two makers was17.32cM.But chromosome3A,3D,4A and5Dwere not included in the map.4. QTL of seven agronomic traits, including plant height, effective tillers, grains perspike, spikelets per spike, spike length, spike and flag leaf distance and compactness, weredetected on chromosome1A,1B,2B,4D,5D,6B and7D The total number of QTL was50.The number of QTL associated with plant height, effective tillers, spike length, grains perspike, spikelets per spike, spike and flag leaf distance and compactness were8,6,6,9,8,7and6respectively.5. In this study,13important regions which controlling different traits were found. Theseregions were Xwmc212-Xgwm99chromosome1A, Xgdm33-Xpsp3003on chromosome4A,Xgwm268-Xwmc419a on chromosome1B, Xgwm448b-Xgwm448a and Me3Em2b-Me7Em13and Xgwm359-Xgwm515on chromosome2A, Xgwm372-Xgwm558b andXgwm501-Me6Em13on chromosome2B, Xbarc251-Xgwm181on chromosome3B,Me8Em8-Me8Em11b on chromosome5A, Me8Em6c-Me3Em2a on chromosome5D,Me3Em2d-Me3Em11a on chromosome6A and Me3Em14a-Me3Em14b on chromosome7D.6. Based on comparison of the results from analysis by major gene and polygene modeland QTL mapping，similar results of genetic law of these7agronomic traits were found.Therefore, results from the two methods can be proved by each other.