<i>BcBRC1a</i> is a negative regulator for tillering in non-heading Chinese cabbage

Abstract

Shoot branching is a decisive factor for crop yield. Molecular mechanism for regulating shoot branching (tillering) needs to be determined. Plenty of previous studies have illustrated that <italic>BRANCHED1</italic> (<italic>BRC1</italic>) is a key integrator of shoot branching regulating signals. However, <italic>BcBRC1</italic> function in non-heading Chinese cabbage (<italic>Brassica campestris</italic> ssp.<italic> chinensis</italic>) (NHCC) remains unknown. Here, we defined two <italic>BRC1</italic> orthologs, <italic>BcBRC1a</italic> and <italic>BcBRC1b</italic>, from NHCC and focused on the <italic>BcBRC1a</italic> gene to describe its alternative splicing characteristic and structure. <italic>BcBRC1a</italic> was expressed rhythmically and mainly in leaf axils at the 'Maertou' cultivar tillering stage. <italic>BcBRC1a</italic>^{<italic>L</italic>} encoded a nuclear location protein. Its ectopic expression caused <italic>Arabidopsis</italic> growth inhibition and silencing <italic>BcBRC1a</italic> led to increased tiller numbers in 'Maertou'. Removing the shoot tips of NHCC caused axillary buds to be released from apical dominance and <italic>BcBRC1a</italic> expression down-regulation. Our research determined that <italic>BcBRC1a</italic> acts as a negative regulator for tillering in non-heading Chinese cabbage and sets the foundation for further studies.