利用QTL-seq技术定位甘蓝型春油菜早花位点cqDTFC8及其近等基因系构建

Mapping of early flowering site cqDTFC8 using QTL-seq technique and construction of its near-isogenic lines in Brassica napus

开花是植物生殖生长的重要阶段,适宜的开花时间对作物的产量具有重要的影响,定位开花基因可以为开花机理的研究奠定基础。本文以已构建完成的甘蓝型春油菜(Brassica napus)花期加倍单倍体(DH)群体为材料,利用数量性状定位测序(QTL-seq)和分子标记辅助选择(MSA)对甘蓝型春油菜中C8染色体上早花位点cqDTFC8进行定位和近等基因系构建。结果表明:早花位点cqDTFC8被定位在C8染色体上1.3~6.0 Mb的范围,该区域共筛选出有多态性位点且在NCBI上有注释的基因20对,其中两个与光周期调控有关,分别为BnaC-08g04860D和BnaC08g04960D。以晚花亲本No.5246为轮回亲本,DH系ZW189为供体亲本,通过前、背景选择进行cqDTFC8位点的近等基因系构建,在BC1F1群体中获得背景回复率为62%的植株12株,在BC2F1中获得回复率85%的22株;将BC3F1中回复率95%以上且含有早花位点cqDTFC8的17株作为近等基因系入选株系。本研究拟为甘蓝型春油菜的早花位点的基因克隆和早花分子育种提供参考依据。

Flowering is an important stage of plant reproductive phase.Appropriate flowering time has direct influence on crop yield.Mapping flowering genes lays a foundation for studying the flowering mechanism.In this study,the doubled haploid(DH)lines of flowering time in Brassica napus was constructed,mapping early flowering site cqDTFC8 on the chromosome C8 of B.napus based on QTL-seq,and constructed near-isogenic lines using molecular marker selection techniques.The results exhibite that the early flowering site cqDTFC8 is located in the range of 1.3–6.0 Mb on the chromosome C8.A total of 20 pairs of genes with polymorphic loci annotated on NCBI were screened out in this region,two of which are associated with photoperiod regulation(BnaC08g04860D and BnaC08g04960D).The late flowering parent(No.5246)and early flowering parent(from DH lines,ZW189)were acted as recurrent and donor parents,respectively.Through constructing the near-isogenic line of cqDTFC8 locus by foreground and background selection,background replied in the BC1F1 population,and there were 12 plants with a rate of 62%;22 strains were with a recovery rate of 85%in BC2F1;17 strains were with a recovery rate of 95%or more in BC3F1,obtaining a near-isogenic group containing the early flowering site cqDTFC8.This study would provide references for gene cloning and early flower molecular breeding of early flowering sites in B.napus.