甘蓝型油菜盐胁迫下幼苗鲜重和干重QTL定位及候选基因分析

盐胁迫是非生物胁迫中影响作物产量的一个主要因素,利用分子标记方法选育油菜耐盐品种对提高油菜产量具有重要意义。选用来自GH06与P174杂交后通过单粒传法连续自交获得的高世代重组自交系群体,以含16 g L–1Na Cl的Hoagland溶液培养幼苗进行盐胁迫处理25 d后,分别测定叶和根的鲜重及干重,根据已构建的高密度SNP遗传连锁图谱进行QTL定位,在QTL物理区间筛选耐盐相关基因并以极端表型材料进行q RT-PCR分析。采用复合区间作图法(CIM),在对照和盐胁迫处理中共检测到19个QTL,其中与盐胁迫相关的有6个,可解释的表型变异7.16%~16.15%,分布在A02、A04和C03染色体上,将QTL置信区间序列和拟南芥中与盐胁迫相关的基因比对分析,共找到8个候选基因。对其中4个候选基因在极端表型材料中的表达分析表明,BnaA02g14680D与BnaA02g14490D基因在盐胁迫处理后的48 h或72 h表达量均高于对照组,即基因的表达由盐胁迫引起,而BnaC03g64030D在敏感型材料中的相对表达量高于在耐盐型材料中,BnaC03g62830D在敏感型材料中没有明显变化,但在耐盐型材料中呈现先升高后降低的表达特征,其表达可能会增强植株对盐胁迫的耐受力。本研究为油菜耐盐基因功能挖掘和油菜耐盐品种选育奠定基础。

QTL Mapping for Seedling Dry Weight and Fresh Weight under Salt Stress and Candidate Genes Analysis in Brassica napus L.

Salt stress is one of the main abiotic stresses affecting crop yield and it would be very important by using the salt tolerance related markers in rapeseed breeding to improve the oilseed production. In this research, the Brassica napus L high generation recombinant inbred lines (RIL) population derived from the cross of GH06 and P174 via single seed descent propagation was used for QTL mapping and candidate gene analysis. The fresh and dry weight of leaf and root were measured at 25 days after the seedlings were grown in Hoagland solution with 16 g L^–1 NaCl. Composite interval mapping (CIM) was used to identify the related QTLs according to the high density SNP genetic map, and the candidate gene expression in the extreme lines tested by qRT-PCR. A total of 19 QTLs were identified in the control and salt stress treatment, and six QTLs were mapped on chromosomes A02, A04 and C03 under salt stress, with contribution rate ranged from 7.16% to 16.15%. Eight genes were identified according to the BLAST of genes in the QTL confidence intervals and the salt stress related genes in Arabidopsis. The expression of four candidate genes in the extreme lines showed that BnaA02g14680D and BnaA02g14490D under salt stress treatment for 48 or 72 hours had higher expression than the control, which indicates that the expressions are induced by salt stress. The relative expressions of gene BnaC03g64030D in sensitive extreme lines were higher than those in tolerant extreme lines. There were no changed in expression for gene BnaC03g62830D in sensitive extreme lines but increased expression at 48 hours and reduced expression at 72 hours after salt treatment in tolerant extreme lines, showing the enhance of plant salt tolerance possibly. Our research laid a foundation for the function research of salt tolerant gene in rapeseed and the breeding of salt tolerant rapeseed.