基于高密度遗传图谱的多环境玉米穗长QTL定位

Multiple-Environment QTL Mapping for Ear Length Trait by Using High-Density Genetic Linkage Map in Maize

玉米是重要的粮食和饲料作物,穗长是影响玉米产量的重要性状之一。本研究以穗长差异显著的玉米自交系SG5及SG7为试验材料配制杂交组合,构建包含199个单株的F_(2)群体,基于前期研究中利用F_(2)群体构建的高密度遗传连锁图谱,结合2014、2018和2019年在海南省三亚市盘县玉米育种试验站种植调查的F_(2)、F_(2∶3)-2018和F_(2∶3)-2019三环境玉米穗长表型数据,利用WinQTLCart2.5的复合区间作图法(CIM)进行全基因组扫描,发掘控制玉米穗长性状的主效QTL位点。结果表明,共检测到5个控制玉米穗长性状的QTL位点qEL-1、qEL-2、qEL-3、qEL-4和qEL-5,分别位于第1、2、3、5、6染色体上,LOD值范围2.5%~16.6%,解释表型变异3.0%~25.6%,其中,qEL-1和qEL-2在三个环境中重复被检测到,qEL-3在F_(2)和F_(2∶3)-2018两个环境中被检测到,qEL-5在F_(2∶3)-2018和F_(2∶3)-2019两个环境中被检测到,而qEL-4只在F_(2)环境中被检测到;qEL-1位点在三环境下解释的表型贡献率均大于20%,LOD值超过15,位于第1染色体。本研究所得结果既可为玉米穗长性状改良提供理论参考,同时也可为研究玉米穗长性状遗传分子机理提供重要依据。

Maize is an important food and feed crop.Ear length(EL)is one of the important traits af-fecting maize yield.In this study,maize inbred lines SG5 and SG7 with obvious differences in EL trait were used as parents to develop F_(2) andF_(2∶3) populations,which containing 199 individuals and 199 lines respective-ly.Based on the high-density genetic linkage map constructed with the F_(2) population in previous study,and combined with the F_(2) EL phenotypic data obtained in 2014(F_(2))and theF_(2∶3) EL phenotypic data obtained from 2018(F_(2)∶3-2018)and 2019(F_(2)∶3-2019)at the Panxian Maize Breeding Experimental Station in Sanya City,Hainan Province,the genome-wide scanning was conducted by the composite interval mapping(CIM)method of WinQTLCart2.5 to identify major QTLs for EL trait in maize.The results showed that a total of 5 QTLs,i.e.qEL-1,qEL-2,qEL-3,qEL-4 and qEL-5,controlling EL trait were detected in the three environments.The 5 QTLs were located on the 1st,2nd,3rd,5th and 6th chromosomes of maize genome,respectively.The LOD value of the 5 QTLs ranged from 2.5%~16.6%,and the phenotypic variation explained by the 5 QTLs ranged from 3.0%~25.6%.Among the 5 identified QTLs,qEL-1 and qEL-2 were repeatedly detected in the three en-vironments,qEL-3 was detected in both F_(2) andF_(2∶3)-2018 environments,qEL-5 was detected in bothF_(2∶3)-2018 andF_(2∶3)-2019 environments,and qEL-4 was only detected in F_(2) environment.The phenotypic contribution rate of qEL-1 located on chromosome 1 in the three environments was greater than 20%,and the LOD value excee-ded 15.The results obtained in this study could not only provide theoretical references for improving EL trait,but also provide important bases for studying the genetic molecular mechanism of maize EL traits.