多环境下的稻谷粒厚QTL定位分析

Analysis on Mapping of Rice Grain Thickness QTLs under Multiple Environments

【目的】粒厚性状是影响水稻产量和稻米食味品质的控制因子之一,运用籼爪交(V20B/CPSLO17)遗传背景的重组自交系(RIL)开展稻谷粒厚QTL定位分析,获得粒厚性状主效QTL,为新的粒厚基因挖掘和开发功能分子标记提供科学依据。【方法】在水稻高密度遗传连锁图谱和籼爪交遗传背景的RIL群体基础上,结合3种不同生态环境(2020年贵州贵阳、2021年贵州贵定、2021年海南三亚)下RIL群体的稻谷粒厚性表型数据,运用IciMapping 4.0软件的ICIM-ADD方法进行粒厚QTL定位及其遗传效应分析。【结果】稻谷粒厚性状在3种生态环境下均呈现连续单峰分布,其受种植环境因子影响不显著。3种不同生态环境的水稻中共检测到分布在第3、5、8和10号染色体上的5个稻谷粒厚QTL(qGT3-1、qGT5-1、qGT5-2、qGT8-1和qGT10-1),它们的增效等位基因均来自亲本V20B,LOD值在3.431~14.081,表型贡献率变幅为5.479%~26.483%。2个QTL(qGT5-1和qGT5-2)的表型贡献率超过10%,其中qGT5-2是唯一在2种生态环境(2020年贵州贵阳、2021年海南三亚)下被反复检测到的,分别解释群体表型变异率的26.483%和14.933%。QTL qGT5-2位点在染色体上的物理距离约为3.9 kb,仅有1个候选基因(LOC_Os05g07920);qGT8-1位点的物理距离约为2.3 kb,仅有1个候选基因(LOC_Os08g10360)。【结论】稻谷粒厚性状呈现出受多基因调控的数量性状遗传特性。qGT5-2是1个稳定遗传且贡献率高的稻谷粒厚主效QTL,对粒厚调控基因挖掘和优质丰产稻新品种培育具有重要的应用潜力。

【Objective】Grain thickness is one of the controlling factors affecting rice yield and taste quality of rice.QTL mapping for grain thickness in rice was conducted by using recombinant inbred lines(RIL)with the indica-japonica cross(V20B/CPSLO17)genetic background and major QTLs of grain thickness were obtained,providing a scientific basis for the discovery of new grain thickness genes and the development of functional molecular markers.【Method】Based on the highdensity genetic linkage map and the indica-japonica cross genetic background of RIL populations,combined with the grain thickness phenotype data of RIL populations under three different ecological environments(Guiyang,Guizhou in 2020;Guiding,Guizhou in 2021;Sanya,Hainan in 2021),QTL mapping and genetic effect analysis were performed by the ICIM-ADD method of IciMapping 4.0 software.【Result】The study showed that the grain thickness trait in rice exhibited a continuous unimodal distribution under all three ecological environments and was not affected by planting environmental factors significantly.Five grain thickness QTLs(qGT3-1,qGT5-1,qGT5-2,qGT8-1,and qGT10-1)were detected on chromosomes 3,5,8,and 10 in rice under the three different ecological environments.The beneficial alleles of these five QTLs were all from the parent V20B,with LOD values ranging from 3.431 to 14.081 and a range of phenotypic contribution rates from 5.479%to 26.483%.Two QTLs(qGT5-1 and qGT5-2)had a phenotypic contribution rate greater than 10%,with qGT5-2 being the only one repeatedly detected in two planting environments(Guiyang,Guizhou in 2020 and Sanya,Hainan in 2021),explaining 26.483%and 14.933%of the population’s phenotypic variance,respectively.The physical distance of QTL qGT5-2 on the chromosome was about 3.9 kb,with only one candidate gene(LOC_Os05g07920);the physical distance of qGT8-1 was about 2.3 kb,with only one candidate gene(LOC_Os08g10360).【Conclusion】Grain thickness in rice is a quantitative genetic trait regulated by multiple genes.qGT5-2 is major QTL with stable heredity and high contribution rate for grain thickness,which has significant application potential in the discovery of grain thickness regulatory genes and the breeding of new high-quality and high-yield rice varieties.