利用三重测交群体剖析玉米株高与穗位高杂种优势的遗传学基础

Heterosis for Plant Height and Ear Position in Maize Revealed by Quantitative Trait Loci Analysis with Triple Testcross Design

以玉米强优势杂交种组合豫玉22及其重组近交系为材料,按照TTC(triple testcross)遗传交配设计,组配了270个测交后代的TTC群体。利用复合区间作图法,对控制株高与穗位高的QTL进行了分析,分别检测到20和17个主效QTL,其中超显性位点最多(11个和8个),加性位点次之(5个和6个),显性位点(2个和0个)和部分显性位点较少(2个和3个)。分析发现,存在同时控制株高与穗位高杂种优势的QTL区域,即Bin1.06区域(umc2151～umc1122)、Bin3.05区域(umc2127～umc2166～umc1539)以及Bin7.03区域(umc1865～umc1888),这也与在各个环境中株高与穗位高的相关性吻合。另外,还分别检测到两性状4个和7个QTL与遗传背景之间的互作,22对和12对标记间的互作,分别解释表型变异的3.26%～16.58%和3.44%～22.41%,说明上位性也可能与这两个性状及其杂种优势的形成有重要关系。

The genetic basis of plant height and ear position for highly heterotic maize hybrid Yuyu 22 was analyzed by using TTC（triple testcross） genetic mating design,with a population including 270 testcross progenies.By using composite interval mapping,the numbers of detected QTLs for plant height and ear position were 20 and 17,respectively.These QTLs for plant height and ear position were classified as overdominant（11 and 8）,additive（5 and 6）,dominant（2 and 0） and partially dominant（2 and 3）.Further analysis indicated that several QTL regions,including Bin1.06（umc2151-umc1122）,Bin3.05（umc2127-umc2166-umc1539） and Bin7.03（umc1865-umc1888）,contributed to both plant height and ear position,which was consistent with the significant correlation between plant height and ear position.One-dimensional genome scan showed four and seven genome regions of QTL × genetic background interactions,22 and 12 marker pairs with epistatic effects for plant height and ear height respectively and the contribution for phenotypic variation was 3.26-16.58% and 3.44-22.41%,which suggests that the contribution of epistasis to the heterosis of the two traits is important.