8种水旱环境下2个玉米群体穗部性状QTL间的上位性及环境互作效应分析

深入剖析干旱胁迫条件下玉米穗部性状的遗传机制可为玉米抗旱高产分子育种提供参考依据。以大穗型旱敏感自交系TS141为共同亲本,分别与小穗型强抗旱自交系廊黄和昌7-2杂交,构建了含有202个(LTPOP)和218个(CTPOP)家系的F2:3群体,在8种水旱环境下进行单穗重、穗轴重、穗粒重、百粒重、出籽率及穗长等6个穗部性状的表型鉴定,并采用复合区间作图法(CIM)和基于混合线性模型的复合区间作图法(MCIM)对其进行单环境和多环境联合数量性状位点(QTL)分析。结果表明,采用CIM法,单环境下在2套F2:3群体间检测到62个穗部性状QTL,其中干旱胁迫环境下检测到38个QTL,进一步在2套F2:3群体多个干旱胁迫环境下检测到10个稳定表达的QTL (sQTL),分别位于Bin 1.01–1.03、Bin 1.03–1.04、Bin 1.05、Bin 1.07、Bin 1.07–1.08、Bin 2.04、Bin 4.08、Bin 5.06–5.07、Bin6.05和Bin 9.04–9.06。采用MCIM法,联合分析定位到54个穗部性状联合QTL,其中24个表现显著的QTL与环境互作(QTL×E), 17对参与了显著的加性与加性/显性(AA/AD)上位性互作,其表型贡献率较低。这些研究结果可为系统地剖析玉米穗部性状的分子遗传机制提供理论依据;且这2套F2:3群体多个环境下检测到的sQTL可作为穗部性状改良的重要候选染色体区段,用于图位克隆或抗旱高产分子育种,但要注重环境及上位性互作效应的影响。

Epistatic and QTL × environment interaction effects for ear related traits in two maize (Zea mays) populations under eight watering environments

Exploring genetic mechanisms of ear related traits in maize (Zea mays) under drought stress is important in maize molecular breeding for drought tolerance and high yield. Two F_2:3 populations, namely 202 F_2:3 families (LT_POP) and 218 F_2:3 families (CT_POP) derived from the common male parent TS141 with drought-sensitive and larger ear and female parents Langhuang/Chang 7-2 with higher drought tolerance and small ear were used to investigate ear weight (EW), cob weight (CW), grain weight (GW), 100-kernel weight (KW), kernel ratio (KR), and ear length (EL) under eight watering environments, and then to analyze quantitative trait locus (QTL) in a single environment by composite interval mapping (CIM) and in the eight environments by mixed linear model based on composite interval mapping (MCIM). Sixty-two QTLs for ear related traits were detected in two F_2:3 populations in a single environment by CIM, among than 38 QTLs were mapped under water-stressed environments, and further analysis showed that ten stable QTLs (sQTLs) were simultaneously identified in two F_2:3 populations under multiple water-stressed environments, these sQTLs were located in Bin 1.01-1.03, Bin 1.03-1.04, Bin 1.05, Bin 1.07, Bin 1.07-1.08, Bin 2.04, Bin 4.08, Bin 5.06-5.07, Bin 6.05, and Bin 9.04-9.06. Fifty-four joint QTLs for ear related traits were identified in the eight environments by joint analysis with MCIM, among than 24 had significant QTL by environment interaction (QTL×E), and 17 significant epistatic interactions with additive by additive/dominance (AA/AD) effects, with less phenotypic variation. These results lay a foundation for systematically revealing molecular genetic mechanism of ear related traits, these sQTLs detected in two F_2:3 populations under multiple environments are important genomic regions that could be used in positional cloning and molecular breeding for drought tolerance and high yield, however, more attention should be paid to the effects of environment or epistatic interaction.