Awakening buds: Navigating tomato axillary bud dormancy from the BRC1 hub

Summary

Plants undergo continuous growth through their main shoot, and specific signals in this growth process trigger the outgrowth of axillary buds. In indeterminate tomatoes, these axillary buds compete for energy with fruit production. Central to this axillary bud regulation is TCP transcription factor (TF) BRANCHED1 (BRC1) playing a key role in suppressing bud outgrowth. Both endogenous and exogenous signals are integrated upstream of BRC1 and depending on the signals BRC1 expression is differentially modulated for either dormancy or outgrowth. In my project, I investigate the transcriptional regulation of BRC1 by employing phylogenetic footprinting to identify its conserved regions. I then applied CRISPR/Cas9-mutagenesis to introduce a large variety of mutations in these sequences. Several mutants exhibited extended periods of bud dormancy. Additionally, I confirmed the binding of specific TF families to these conserved regions. These results underscore the highly conserved BRC1 regulation across different plant species and enlighten the critical regulators involved in BRC1-dependent axillary bud outgrowth. Decoding these regulatory sequences could enhance our understanding of bud development, therefore contributing to the improvements of plant architecture in the future.