BnA10.RCO, a homeobox gene, positively regulates leaf lobe formation inBrassica napusL.

摘要

Key message BnA10.RCO positively regulates the development of leaf lobes in Brassica napus, and cis-regulatory divergences cause the different allele effects. The functional importance of lobed leaves in rapeseed (Brassica napusL.) has been identified with potential advantages for high-density planting and hybrid production. Our previous studies indicated that the tandemly duplicatedLMI1-like genesBnA10. RCOandBnA10.LMI1are candidate genes of an incompletely dominant locus, which is responsible for the lobed-leaf shape in rapeseed. We provided strong evidence thatBnA10.LMI1positively regulates leaf lobe formation. Here, we show thatBnA10.RCOis a nucleus-specific protein, encoding an HD-ZIP I transcription factor, which is responsible for the lobed-leaf shape in rapeseed. Sequence analysis of parental alleles revealed that no vital sequence variation was detected in the coding sequence ofBnA10.RCO,whereas abundant variations were identified in the regulatory regions. Consistent with this finding, the expression level ofBnRCOwas substantially elevated in the lobed-leaved parent HY compared with its near-isogenic line. Moreover, the altered expression ofBnA10.RCOin transgenic lines showed a positive connection with leaf complexity without a substantial change inBnLMI1transcript level. Furthermore, CRISPR/Cas9-induced null mutations ofBnA10.RCOin the lobed-leaved parent HY were sufficient to produce an unlobed leaf without alteration inBnLMI1transcript level. Our results indicate thatBnA10.RCOfunctions together withBnA10.LMI1to positively determine the lobed-leaf development, providing a fundamental basis for crop improvement by targeting leaf shape in rapeseed.