基于高密度遗传图谱的水稻糙米籽粒大小QTL定位

Mapping of QTLs for Rice Grain Size Based on High-density Genetic Map

【目的】籽粒大小是影响水稻产量的主要农艺性状之一。采用籼稻品种V20B与细长型爪哇稻品种CPSLO17衍生的重组自交系开展水稻糙米籽粒大小QTL定位研究,挖掘遗传稳定的主效QTL,为优质高产稻品种培育提供新的基因资源和科学依据。【方法】基于V20B/CPSLO17遗传背景的高密度遗传连锁图谱,结合150份重组自交系在4种环境(2019年贵州贵阳、2020年贵州贵阳、2021年贵州贵定、2021年海南三亚)中的糙米籽粒大小表型数据,采用IciMapping 4.0软件的ICIM-ADD方法进行QTL扫描。【结果】亲本V20B的糙米籽粒大小显著大于CPSLO17,重组自交系的糙米籽粒大小在4种环境间差异显著,均表现出连续的单峰分布。4种环境共检测到分布于7条染色体上的11个与糙米籽粒大小相关的QTL,LOD值均介于3.00~14.57之间。4个QTL(qRGS5、qRGS7.1、qRGS7.2和qRGS11.3)的表型贡献率超过10%,其中qRGS5在4种环境中均被重复检测到,分别解释群体表型变异率的29.71%、28.77%、17.27%和12.50%。3个QTL(qRGS2.1、qRGS2.2和qRGS12)的增效等位基因源自亲本CPSLO17,8个QTL(qRGS4.1、qRGS5、qRGS7.1、qRGS7.2、qRGS8、qRGS11.1、qRGS11.2和qRGS11.3)的增效等位基因源自亲本V20B,qRGS5在4种环境中的增效等位基因均源自亲本V20B。【结论】亲本V20B和CPSLO17间糙米籽粒大小差异极显著,糙米籽粒大小性状易受环境影响。QTL qRGS5是影响糙米籽粒大小且遗传稳定的主效QTL,在糙米籽粒大小性状基因挖掘和高产优质稻分子育种中具有潜在的应用价值。

【Objective】Grain size is one of the main agronomic traits affecting rice yield.A recombinant inbred line population derived from indica rice variety V20B and slender javanica rice variety CPSLO17 was used for QTL mapping of brown rice grain size.It aims to explore the genetically-stable main effect QTLs,providing new genetic resources and scientific basis for developing high-quality and high-yield rice varieties.【Method】Based on the high-density genetic linkage map of V20B/CPSLO17 genetic background,the brown rice grain size phenotype data of 150 recombinant inbred lines under four environments(Guiyang,Guizhou in 2019,Guiyang,Guizhou in 2020,Guiding,Guizhou in 2021,and Sanya,Hainan in 2021)were used for QTL scanning by the ICIM-ADD method of IciMapping 4.0 software.【Result】The grain size of brown rice from parent V20B was significantly larger than that from CPSLO17,and the grain sizes of brown rice from recombinant inbred lines showed significant differences among the four environments,all exhibiting a continuous unimodal distribution.A total of 11 QTLs related to brown rice grain size distributed on 7 chromosomes were found in the four environments,with their LOD values ranging from 3.00 to 14.57.Four QTLs including qRGS5,qRGS7.1,qRGS7.2,and qRGS11.3 had a phenotypic variance explained(PVE)over 10%,of which the qRGS5 was repeatedly detected in all four environments,with its PVE of 29.71%,28.77%,17.27% and 12.50%,respectively.The synergistic alleles of three QTLs(qRGS2.1,qRGS2.2 and qRGS12)derived from the parent CPSLO17,while the other eight synergistic alleles(qRGS4.1,qRGS5,qRGS7.1,qRGS7.2,qRGS8,qRGS11.1,qRGS11.2 and qRGS11.3)derived from the parent V20B,and the synergistic alleles of QTL qRGS5 detected in all four environments derived from the parent V20B.【Conclusion】The difference of brown rice grain size between parents V20B and CPSLO17 is extremely significant.The brown rice grain size trait is affected by the environments.The QTL qRGS5 is a genetically-stable main effect QTL that affects grain size in brown rice,which has practical value in new gene discovery for brown rice grain size and molecular breeding for high-yield and high-quality rice.