Yu-qin TU, Jia-jia XIN, Yang ZHANG, Nan-feng ZHANG, Xing-lin DAI, Wei-feng TU, Jie TANG
Rapeseed (Brassica napus L.) is the largest oil crop in China, and the mechanized production is the inevitable trend of rapeseed industry. But the long flowering period and inconsistencies of silique mature caused by indeterminate inflorescence in rapeseed are key links affecting mechanized harvest. Therefore, gene mapping, candidate gene prediction and cloning of the determinate inflorescence trait are of great significance for the genetic improvement of rapeseed, the cultivation of new varieties suitable for mechanized harvest and the breaking of the bottleneck of rapeseed mechanized production. A natural and novel rapeseed mutant with determinate inflorescence was identified in this study. The F2 isolated population was constructed by crossing with Zhongshuang 11(ZS11).Two pools with 20 determinate and indeterminate inflorescence F2 lines were used for gene mapping of determinate inflorescence, 20× and 10× depth of whole genome re-sequencing were conducted for the two pools and parental lines, respectively. A total of 277 679 SNP and 302 625 InDel polymorphic sites were identified for whole genome mapping of determinate inflorescence traits. Using the △ SNP-index method for association analysis, a total of 892 polymorphic marker loci were screened, containing 683 genes, which were mapped on six significantly associated interval of chromosome A09, A10 and C09, of which, the locus on chromosome C09 exhibited the highest peak. By A. thaliana genome homologous sequence alignment, combined with gene functional annotation and sequence difference analysis, genes of BnaA09g34410D, BnaA09g37880D, BnaA09g38520D, BnaC09g40470D, BnaC09g40480D and BnaC09g49710D were predicted as potential candidate genes of determinate inflorescence within the association interval on chromosomes A09 and C09. The genes of BnaA09g34410D, BnaA09g37880D and BnaC09g49710D were involved in the control of flower development and flowering time, and the three genes located within associated interval of chromosome C09 with the highest peak having sequence differences of allelic genes, were predicted as the main genes controlling this determinate inflorescence trait. The results establish the theoretical foundation for the cloning and function identification of the determinate inflorescence genes in rape.