杂交棉‘冀1518’纤维品质性状的QTL定位及遗传分析

QTL Mapping and Genetic Analysis of Fiber Quality Traits in Hybrid Cotton ‘Ji1518’

‘冀1518’是以优质品种‘冀228’为母本,丰产品系‘冀567’为父本配制的适机采杂交棉新品种,为挖掘‘冀1518’的优异纤维品质相关分子标记,本研究利用杂交棉‘冀1518’的亲本构建了F_(2)、F_(2:3)和F_(2:9)(重组近交系)(recombinant inbred lines,RILs)三个世代的分离群体,并利用SSR分子标记分别以F_(2)群体和RIL(F_(2:9))群体构建遗传连锁图谱,并对纤维品质性状进行定位。结果表明,F_(2)作图群体共有15个标记位点连锁,包含4个连锁群,全长覆盖237.10 cM,RIL(F_(2:9))作图群体共有45个标记位点连锁,包含11个连锁群,全长覆盖554.42 cM。利用QTL IciMapping 4.1对F_(2)、F_(2:3)和RIL(F_(2:9))群体的纤维品质性状进行复合区间作图法分析,在F_(2)及F_(2:3)分离群体能同时检测到15个与纤维品质相关的QTLs,其中,与马克隆值相关的QTL位点q FM-4-2解释表型变异率最高,为21.10%,显性或超显性效应的QTLs占总数的66.7%,表明显性基因是‘冀1518’纤维品质杂种优势的主要来源。在RIL(F_(2:9))群体定位到6个与纤维品质性状相关的QTLs,解释表型变异率在5.10%~10.26%之间。F_(2)、F_(2:3)和RIL(F_(2:9))群体均能在HAU2349附近(F_(2:9)作图,0.31 cM)检测到与断裂比强度和马克隆值相关的QTL位点,在HAU2710附近(F_(2:9)作图,0.84 cM)检测到与整齐度相关的QTL位点,且上述两标记连锁,连锁区段被定位在A6染色体上。本研究获得在多世代中稳定表达的QTLs,有望用于纤维品质分子标记辅助选择,提高育种效率。

‘Ji1518’is a new hybrid cotton variety suitable for mechanized harvesting,the two parents of‘Ji228’and‘Ji567’were crossed to established F_(2),F_(2:3) and F_(2:9)(recombinant inbred lines RILs)population.Simple sequence repeats(SSR)was performed to construct two different genetic maps based on the F_(2) and F_(2:9) populations respectively.The QTL mapping of five fiber quality traits was performed in three populations above.A genetic map was constructed by F_(2) population,which contained 15 loci in 4 linkage groups,with a full-length coverage of 237.10 cM.While the other linkage map was constructed by F_(2:9) population,which contained 45 loci in 11 linkage groups,with a full-length coverage of 554.42.Based on the inclusive composite interval mapping method with QTL IciMapping4.1,15 QTLs related to upper half mean length,fiber strength,the micronaire value,the elongation and the uniformity were both detected in F_(2) and F_(2:3) segregating populations,among them,the QTL locus qFM-4-2 related to the micronaire value explained the highest phenotypic variation rate at 21.10%.QTLs with dominant or superdominant effects accounted for 66.7%of the total,which showed that dominant genes were the main source of fiber quality heterosis in‘Ji1518’.Meanwhile,6 QTLs related to the above five traits of fiber quality were detected in the RIL(F_(2:9))population,and the contribution rate was between 5.10%and 10.26%.QTL loci related with FS and MIC were detected near HAU2349 in all three populations,and QTL loci related with FU were detected near HAU2710 in all three populations,and the markers above were linked on A6 chromosome.These stable and common QTLs are beneficial to the MAS breeding,which could improve the breeding efficiency.