Comparative Transcriptome Analysis Provides Insights into Molecular Pathway and Genes Associated with Heading Type Formation and phenotypic divergence in Chinese Cabbage

The purpose of this study is to analyze the formation mechanism of bulb-holding type of diploid and tetraploid Chinese cabbage. The ploidy of diploid and tetraploid Chinese cabbage with overlapping and outward-curling types were determined by flow cytometry. The results of transcriptome analysis showed that the differential expressed genes (DEGs) involved in seven hormone pathways: Abscisic acid, Auxin, Brassinosteroid, Cytokinine, Ethylene, Gibberellin, and Jasmonic acid. Among them, more DEGs were enriched in Abscisic acid and Auxin pathway, accounting for 35.29% and 27.94% of the total DEGs. In the Auxin hormone pathway, there are 17 common differential genes in the folded and symbiosis type of diploid and tetraploid Chinese cabbage. In the Abscisic acid hormone pathway, there are 15 common DEGs in the folded and symbiosis type of diploid and tetraploid Chinese cabbage. There are only 9 DEGsin the Auxin hormone pathway and 3 DEGs in the Abscisic acid hormone pathway in the tetraploid folded and symbiosis Chinese cabbage. Ten genes were randomly selected from the total DEGs for qRT-PCRverification , which further confirmed the accuracy of transcriptome data. The results of this study showed that the formation of diploid and tetraploid leaf bulb types was closely related to Auxin and Abscisic acid, and 12 DEGs were found only in tetraploid overlap and overlap type Chinese cabbage, which were closely related to the formation of leaf types in tetraploid Chinese cabbage.