Comparative Analysis of SUS in Chinese Cabbage, Black Mustard, and Cabbage, and Their Diurnal Expression Response to Light

Sucrose synthase plays a crucial role in sucrose metabolism and flower regulation. By using bioinformatics techniques, 13, 16 and 13 SUS members were identified in Brassica rapa, Brassica nigra, and Brassica oleracea, respectively. The SUS family can be divided into three subfamilies. The SUS II subfamily has three B. nigra genes with significantly reduced motif types. The SUS III subfamily has fewer motif 2 in Arabidopsis thaliana compared to the other species. The interspecific collinearity analysis revealed a “one-to-one, many-to-one” relationship between species. KEGG revealed that Brassica nigra showed significantly higher enrichment in the metabolism pathway, while Brassica rapa and Brassica oleracea exhibited higher significance in carbohydrate metabolism. GO indicated that Brassica nigra had more enriched biological process pathways than the other two species. It reveals that SUS has a higher degree of similarity between the AA genome and the CC genome, while its similarity to the BB genome is lower. The analysis of the response of BraSUSs to different light intensities revealed that the differentially expressed genes BraA07g028740.3C and BraA07g037520.3C had enhanced expression rhythms under high light intensity. Using three diploid basal species with different flowering traits (Chinese cabbage, cabbage, and black mustard) as experimental materials, we conducted a comparative analysis of the SUS gene family. This will lay the foundation for deciphering the molecular regulatory mechanism by which the SUS gene affects flowering through its influence on sucrose synthesis.