陆地棉耐镉胁迫的遗传与QTL定位分析

QTL mapping and genetic analysis of cadmium stress tolerance in upland cotton

【目的】棉花是1种较耐重金属镉的作物,培育与种植耐镉胁迫棉花品种对于镉污染土壤的修复具有重要意义。本文旨在研究陆地棉耐镉性的遗传并对相关数量性状位点(quantitative trait locus, QTL)进行定位分析。【方法】以陆地棉种质HS46和MARCABUCAG8US-1-88为亲本构建的188个重组自交系(recombinant inbred line, RIL)为材料,调查RIL群体在镉胁迫条件下的发芽率、发芽势,以及苗期叶片的叶绿素含量、株高和干/鲜物质质量等表型数据,并计算各家系的镉胁迫系数;采用完备区间作图法对RIL群体的各性状的镉胁迫系数及镉胁迫综合系数进行QTL定位和遗传分析。【结果】MARCABUCAG8US-1-88为耐镉材料,HS46则为镉敏感材料,188个RIL家系的耐镉性相关性状基本服从正态分布,包含强耐镉型材料23份、耐镉型材料49份、中等耐镉型材料67份、镉敏感型材料49份。连锁分析共鉴定到28个与镉胁迫系数相关的QTL,分布于14条染色体上,单个位点解释1.58%~8.41%的表型变异,其中根鲜物质质量镉胁迫系数位点qRFW-13-1在2个环境下均被检测到,分别解释7.66%和7.71%的表型变异。【结论】棉花耐镉性为多基因控制的数量遗传,受环境影响较大,定位到的耐镉QTL qRFW-13-1为稳定QTL,该结果对于棉花耐镉分子育种具有一定的应用价值。

[Objective]Cotton is a relatively tolerant crop to cadmium(Cd)stress.It is of great significance to breeding and extending the Cd tolerant cotton cultivars for remediation of Cd contaminated soil.This study aims to analysis the inheritance of cotton tolerance to Cd stress and to map the quantitative trait locus(QTL)related to Cd stress.[Methods]In this study,188 recombinant inbred lines(RIL)called HM188 derived from an intraspecific hybrid between HS46 and MARCABUCAG8US-1-88 were used to study the phenotypic data of germination rate,germination potential,chlorophyll content,plant height,dry and fresh weight at seedling stage under Cd stress,and the Cd stress coefficient of each material was calculated as well.QTL mapping was conducted for each trait and Cd stress coefficient of HM188 population by using complete interval mapping method.[Results]According to the performance and Cd stress coefficient of each trait under Cd stress,MARCABUCAG8US-1-88 was the Cd tolerant parent,while HS46 was a sensitive one.The Cd tolerance of 188 RIL was basically normal distribution,including 23 strong Cd tolerant lines,49 Cd tolerant line,67 medium tolerant lines,and 49 sensitive lines.A total of 28 QTL for Cd stress coefficient was identified,which were distributed on 14 chromosomes with explaining of variation of 1.58%~8.41%.Among them,qRFW-13-1 related to root fresh weight was detected in both environments,which explained variation of 7.66%and 7.71%,respectively.[Conclusion]Cd tolerance in upland cotton is a quantitative trait controlled by multiple genes,which was greatly affected by the environment.However,qRFW-13-1 for Cd tolerance may be a stable QTL,which has some application values in molecular breeding for Cd tolerant cotton.