New Insights into the TIFY Gene Family of Brassica napus and Its Involvement in the Regulation of Shoot Branching

As plant-specific transcription factors, the TIFY family genes are involved in the responses to a series of biotic and abiotic stresses and the regulation of the development of multiple organs. To explore the potential roles of the TIFY gene family in shoot branching, which can shape plant architecture and finally determine seed yield, we conducted comprehensive genome-wide analyses of the TIFY gene family in Brassica napus. Here, HMMER search and BLASTp were used to identify the TIFY members. A total of 70 TIFY members were identified and divided into four subfamilies based on the conserved domains and motifs. These TIFY genes were distributed across 19 chromosomes. The predicted subcellular localizations revealed that most TIFY proteins were located in the nucleus. The tissue expression profile analyses indicated that TIFY genes were highly expressed in the stem, flower bud, and silique at the transcriptional level. High-proportioned activation of the dormant axillary buds on stems determined the branch numbers of rapeseed plants. Here, transcriptome analyses were conducted on axillary buds in four sequential developing stages, that is, dormant, temporarily dormant, being activated, and elongating (already activated). Surprisingly, the transcription of the majority of TIFY genes (65 of the 70) significantly decreased on the activation of buds. GO enrichment analysis and hormone treatments indicated that the transcription of TIFY family genes can be strongly induced by jasmonic acid, implying that the TIFY family genes may be involved in the regulation of jasmonic acid-mediated branch development. These results shed light on the roles of TIFY family genes in plant architecture.