联合QTL定位和转录组分析揭示玉米开花期的遗传基础

开花期对玉米适应不同环境具有决定性作用,是重要的育种目标,对玉米开花期进行QTL定位是进行花期性状改良的基础工作。以玉米自交系黄早四和1462为亲本构建的F_2:3群体为材料,结合高密度SNP标记对玉米抽雄期和散粉期进行QTL定位。结果表明,F_2:3群体的抽雄期和散粉期呈正态分布,且两性状之间呈极显著相关。利用WinQTLcart 2.5软件的复合区间作图法共检测5个控制抽雄期的QTL,分别位于3、5、6、7、9号染色体上,贡献率在6.19%～26.39%;同时检测到4个控制散粉期的QTL,位于3、5、6、7号染色体上,贡献率7.48%～28.28%,这些QTL的基因作用方式以部分显性和超显性为主。共计发现3个主效QTL(贡献率超过10%),分别位于3号和6号染色体上。利用两个亲本的V6时期的茎尖进行转录分析,在主效QTL置信区间内共发现21个差异表达基因,其中包含可能控制玉米花期的候选基因。

Combining QTL Mapping and RNA Sequencing Analysis to Dissect the Genetic Basis of Flowering Time in Maize

Flowering time is an important adaptive trait and is a target trait in maize breeding.Mapping quantitative trait locus/loci (QTL) controlling flowering time is the basic work for improving maize flowering time.In order to map the QTL controlling maize flowering time,an F_2:3 population was constructed by crossing maize inbred lines Huangzaosi and 1462,the population was evaluated for days to tasseling (DTT) and days to anthesis (DTA),and genotyped with high-density SNP markers.The result showed that DTT and DTA had strong correlation,and both traits showed normal distribution.A total of five QTL controlling the stage of male twitching were detected using compound interval mapping with WinQTLcart 2.5 software,located on chromosomes 3,5,6,7 and 9,with contributions ranging from 6.19% to 26.39%.For DTA,4 QTLs were also detected,located on chromosomes 3,5,6,and 7,and the phenotypic variances explained by these QTL ranged from 7.48% to 28.28%.These QTLs mainly showed partially dominance or over-dominance.To find candidate genes underlying three major QTL (explaining>10% phenotypic variance),RNA sequencing analysis was performed using V6-stage shoot tips of the parental lines.A total of 21 differentially expressed genes were found in the confidence interval of the major QTL,and might contain the candidate genes for maize flowering time.