水稻不育系抽穗包颈性状的遗传研究

Research on Inheritance of Panicle-enclosure Related Traits of Male Sterile Lines in Rice

为了探讨水稻不育系抽穗包颈性状的遗传基础,且为选育不包颈或包颈轻的不育系提供依据,本研究利用W9593S(抽穗包颈轻)与培矮64S(抽穗包颈重)2个光温敏核不育系杂交、回交构建遗传群体,采用植物数量性状主基因+多基因混合遗传体系的6世代联合分离分析方法,剖析了水稻不育系抽穗包颈性状的遗传模型,并与F2群体QTL定位结果进行比较分析。结果表明:经分离分析,穗粒外露度、包颈长均表现为B-1模型(2对加性-显性-上位性主基因模型);包颈度、顶1节间长和剑叶鞘长的最适模型分别为D-4(1对负向完全显性主基因+加性-显性多基因遗传模型)、D-1(1对加性-显性主基因+加性-显性多基因遗传模型)和C-0模型(加性-显性-上位性多基因遗传模型)。对F2分离群体进行QTL定位,共检测到分别与穗粒外露度、包颈长、包颈度、顶1节间长和剑叶鞘长有关的25个QTL,分布于第1、第2、第4、第5、第6、第7和第12染色体上,表型贡献率变幅为2.85%~16.73%。其中位于第12染色体与SSR标记RM3331连锁的QTL以及位于第6染色体分别与SSR标记RM439和RM3765连锁的QTL均同时影响穗粒外露度、包颈长和包颈度3个性状,位于第4染色体分别与SSR标记RM255和RM3687连锁的QTL同时影响顶1节间长和剑叶鞘长2个性状,这5个QTL位点可能是调控不育系抽穗包颈性状的重要位点。QTL定位结果与6世代分离分析结果在某种程度上具有相似性,又不完全一致,可能与这两种方法依据的遗传群体不同以及数量性状受环境影响较大有关。

To explore the genetic basis of panicle-enclosure related traits of male sterile lines in rice for breeding male sterile lines without or with only slight panicle-enclosure,six sterile populations of P1,P2,F1,B1,B2 and F2were constructed by crossing and backcrossing between Pei'ai 64 S,a PTGMS line with heavier panicle-enclosure,and W9593 S,a PTGMS line allelic to Pei'ai 64 S in male sterility with slighter panicle-enclosure.The genetic models of panicle-enclosure related traits of male sterile lines were dissected by the joint segregation analysis method of six populations of the mixed genetic system for major genes and polygenes of plant quantitative traits and compared with the QTL mapping results based on F2 population.The results showed that both panicle exsertion degree(PED) and panicle enclosed length(PEL) were matched to Model B-1(the genetic model for two pairs of additive-dominant-epistatic major genes) by the joint segregation analysis.Model D-4(the genetic model for a pair of negative completely dominant major genes plus additive-dominant polygenes),Model D-1(the genetic model for a pair of additive-dominant major genes plus additive-dominant polygenes) and Model C-0(the genetic model for additive-dominant-epistatic polygenes) were most suitable for panicle length enclosed rate(PLER),the uppermost internode length(UIL) and flag leaf sheath length(FLSL),respectively.The F2 population consisting of325 plants was used to identify QTLs for panicle-enclosure related traits.A total of 25 QTLs related to PED,PEL,PLER,UIL and FLSL were detected on Chromosomes 1,2,4,5,6,7 and 12,explaining individually a phenotypic variation from 2.85% to 16.73%.Among them,the QTL linked to RM3331,a SSR marker on Chromosome 12,and the QTLs linked to markers RM439 and RM3765,respectively,on Chromosome 6 affected PED,PEL and PLER simultaneously and the QTLs linked to markers RM255 and RM3687,respectively,on Chromosome 4controlled simultaneously UIL and FLSL,indicating that these five QTLs may be the important loci regulating panicle-enclosure related traits of male sterile lines in rice.There was a similarity in a way but it was not in full accord between the QTL mapping and the joint segregation analysis results,probably resulting from the difference of the genetic populations used by the two methods and the greater environmental effects of quantitative traits.