基于高密度遗传图谱的水稻分蘖角度QTL定位与分析OA

[Objective]Tiller angle is an important component of rice plant type,which directly affects rice planting density and ultimately influences rice yield.Exploring and studying new QTLs/genes that regulate rice tiller angle and applying them to plant type improvement is one of the effective ways to improve rice yield.[Method]The recombinant inbred lines(RILs)derived from the crossing and selfing of the Indian japonica rice variety M494 and indica rice variety Zhong 9B were used as experimental materials.They were planted at Fuyang and Lingshui experimental bases of China National Rice Research Institute in Zhejiang and Hainan Province from 2021 to 2023.QTL mapping and analysis of rice tiller angle were conducted based on the high-density Bin map constructed by resequencing method.[Result]A total of nine QTLs were detected in three years,distributed on chromosomes 1,3,9,11 and 12.The phenotypic variation explained by each QTL ranged from 2.54%to 57.00%,and the additive effects were all derived from the large tiller angle parent M494.Among them,the major QTL qTA9-1 for tiller angle was located in the range of 20.71-20.80 Mb on chromosome 9,with a physical map interval of 86.36 kb region.Moreover,it was repeatedly detected in 2021 and 2022,and the highest contribution rate could reach 57.00%.This region overlapped with the cloned tiller angle gene TAC1.The RT-PCR results showed that the expression level of TAC1 in the large tiller angle genotype line M109 was significantly higher than that in the small tiller angle genotype line M67.Further sequencing analysis revealed that compared with the qta9-1 genotype line M67,the qTA9-1 genotype line M109 had a C to T mutation at the 3'splice site of intron 4 of the reported TAC1,which is the TAC1 functional SNP,and we speculate that qTA9-1 is TAC1.In 2021 and 2022,a novel QTL controlling tiller angle was repeatedly detected in the 15.20-16.00 Mb interval of chromosome 3,which exhibited epistatic interaction with the major tiller angle QTL qTA9-1.A minor QTL locus regulating tillering angle was repeatedly detected in the 21.10-22.02 Mb interval of chromosome 12.[Conclusion]Nine QTLs for tiller angle were detected using the RIL population constructed by crossing M494 with Zhong 9B combining with the high-density genetic map,including the cloned gene TAC1,and a novel QTL for tiller angle was detected on chromosome 3.The above results provide a theoretical basis and genetic resources for further fine mapping of rice tiller angle genes and genetic improvement of plant type of rice varieties.