VvBRC inhibits shoot branching in grapevine

Abstract The BRANCHED1 (BRC1) gene has been reported as a key regulator of shoot branching in many model plants. However, its role in the shoot branching process of grapevine has not been described. In this present study, we isolated VvBRC, a member of the Teosinte branched 1/cycloidea/proliferating cell factor 1 (TCP) transcription factor family, from grapevine (Vitis vinifera L.). The VvBRC protein was localized in the nucleus. RT-qPCR analysis showed that VvBRC was primarily expressed in grapevine prompt and latent buds and stems. Moreover, VvBRC expression in grapevine prompt buds was suppressed in response to decapitation, and induced in response to hormones such as cytokinin and gibberellin. Heterologous overexpression of VvBRC inhibited plant shoot branching in transgenic Arabidopsis, and complementary expression restored the phenotype in mutant Arabidopsis thaliana. In addition, transcript levels of genes participating in ABA biosynthesis, such as NCED, and ABA signaling pathways, such as ABF3, ABI5, HB21, HB40, and HB53, were upregulated, whereas the transcript levels of genes involved in the cell cycle, such as CYCD3 and HISTONE H4, were downregulated in VvBRC-overexpressing plants. Collectively, these results suggest that VvBRC play critical and negative roles in grapevine shoot branching.