蓖麻有效穗数QTL定位及候选基因鉴定

QTL Mapping and Candidate Gene Identification of Effective Spike Number in Ricinus communis L.

有效穗数是蓖麻产量的重要构成因子。为揭示蓖麻有效穗数的遗传基础及挖掘其候选基因,利用表型差异显著的2个亲本杂交构建F_(2)和BC_(1)(F_(1)×P_(2))群体,通过SSR引物基因分型以及CIM和ICIM-ADD 2种检测方法对单株有效穗数和一级分枝有效穗数进行QTL定位,并以相同方法在S 1群体进一步验证QTL重复性。在F 2群体中共检测到9/5(CIM/ICIM-ADD,下同)个QTL,其中,单株有效穗数和一级分枝有效穗数QTL分别为3/2,6/3个,分别解释了6.70%/11.87%和25.15%/13.87%的表型变异。BC 1群体的定位结果与F 2群体基本一致。其中,qESNPP3.1和qEPBSN3.1为稳定QTL,贡献率都接近10%,后者在S 1群体中再次检测到,贡献率为13.27%;它们在RCM915~RCM950标记区间内重叠分布,共同构成1个调控蓖麻有效穗数的主效QTL簇。从RCM915~RCM950标记区间中共鉴定了2个蓖麻有效穗数候选基因(即Rc-US03g04880和Rc-US03g05950),它们在双亲多个分枝组织中差异表达。上述结果为蓖麻有效穗数的标记辅助选择提供了重要的分子标记,也为其遗传和生理机理研究提供了必要的候选基因。

Effective spike number is an important component of castor yield.In order to reveal the genetic basis and mining candidate genes of effective spike number,the QTLs conferring effective spike number per plant(ESNPP)and number of effective primary branch spike(EPBSN)were mapped by genotyping with SSR primers and by the 2 detection methods(CIM and ICIM-ADD)in the populations F 2 and BC 1(F 1×P 2)derived from 2 parents with significant phenotypic differences,and QTL remapping was conducted in S 1 population by the same method.A total of 9/5(CIM/ICIM-ADD,the same below)QTLs were identified in the F 2 population,including 3/2 and 6/3 underlying ESNPP and EPBSN,with a phenotypic variation explained(PVE)of 6.70%/11.87%and 25.15%/13.87%,respectively.The mapping results in BC 1 population were generally consistent with those in F 2 population.Among them,qESNPP3.1 and qEPBSN3.1 were stable QTLs with contribution rates close to 10%,and the latter was detected again in S 1 population with a PVE of 13.27%;the stable QTLs were overlappingly located in the marker interval RCM915-RCM950,and together constituted a main-effect QTL cluster underlying the effective spike number.Two candidate genes,Rc-US03g04880 and Rc-US03g05950,were annotated from the marker interval,which were differentially expressed in multiple branching tissues of both parents.The above results provided essential molecular markers for marker-assisted selection of the effective spike number and necessary candidate genes for its genetic and physiologic mechanism study in castor.