甜玉米根系相关性状的QTL定位

QTL mapping of root related traits in sweet corn

[目的]研究甜玉米根系相关性状的QTL,为甜玉米耐密、抗倒伏和抗逆育种提供理论依据。[方法]应用复合区间作图法,以甜玉米组合T49×T56的F_(2)为作图群体,测定F_(2∶3)家系的根长、根干质量和节根层数,并进行QTL定位。[结果]甜玉米遗传连锁图谱包含153个SSR位点,图谱全长1 199.1 cM,平均间距7.83 cM。检测到2个与根长相关的QTL位于第2、8染色体上,贡献率分别为19.70%和18.20%;5个与根干质量相关的QTL位于第3、4、8染色体上,单个QTL可解释5.28%~17.24%的表型变异;3个与节根层数相关的QTL位于第3、8染色体上,单个QTL贡献率为9.38%~21.13%。第8染色体检测到1个同时控制根长和根干质量的QTL位于bin8.02区域,且与1个bin8.02-8.03区域控制节根层数的QTL紧密连锁,可分别解释18.20%,17.24%和21.13%的表型变异;1个同时控制根干质量和节根层数的QTL位于bin8.03区域,贡献率分别为17.13%和18.82%。[结论]第8染色体上在同一区域内出现控制不同性状的QTL。育种实践中,可利用根长、根干质量和根层数3个性状共同检测到的主效QTL及QTL富集区,进行分子标记辅助选择和遗传改良。

[Objective] The aim of this study was to study QTL mapping of root related traits in sweet corn to help better breed varieties with tolerance, lodging resistance and stress resistance.[Method] The root length, root dry weight and number of nodal root layers of F_(2∶3) family from F_(2) generation of the T49×T56 cross were measured and QTLs for related traits were mapped by composite interval mapping method.[Result] The linkage map contained 153 SSR markers, covering 1 199.1 cM of maize genome with an average distance of 7.83 cM.Two QTLs related to root length were located on chromosomes 2 and 8,explaining 19.70% and 18.20% of phenotypic variation.Five QTLs related to root dry weight were located on chromosomes 3,4 and 8,and a single QTL could explain 5.28%-17.24% of phenotypic variation.Three QTLs related to number of nodal root layers were located on chromosomes 3 and 8,and a single QTL can explain 9.38%-21.13% of phenotypic variation.A QTL simultaneously controlling root length and root dry weight was found on chromosome bin8.02 and it was closely linked to a QTL controlling number of nodal root layers on chromosome bin8.02-8.03.They could explain 18.20%,17.24% and 21.13% phenotypic variations, respectively.A QTL simultaneously controlling root dry weight and number of nodal root layers was detected on chromosome bin8.03,explaining 17.13% and 18.82% of phenotypic variations.[Conclusion] The QTLs controlling different traits were found in the same region on chromosome 8.The main QTLs and the rich and overlapping regions of QTLs co-detected by three traits can be carried out using molecular marker-assisted selection and genetic improvement in breeding practice.