Mutation in BrCLF resulted in leaf curling phenotype in Chinese cabbage

Leaf morphology directly affects photosynthetic capacity, leafy head formation, and product quality in Chinese cabbage. In this study, we identified a leaf curling mutant clm1 from the EMS mutagenized population of Chinese cabbage. Genetic analysis showed that the mutant phenotype was controlled by a single recessive nuclear gene. MutMap analysis combined with KASP genotyping identified BrCLF as the causal gene, with a C-T substitution in the eighth exon resulting in a R-K amino acid change. VIGS result and sequencing analysis of allelic mutants between clm1 and clm2 validated that BrCLF mutations caused leaf curling. Paraffin section analysis revealed disorganized leaf cells and thicker spongy tissue in the mutant. In situ hybridization showed that BrCLF was mainly expressed in palisade cells and spongy mesophyll. Transcriptomic analysis and RT-qPCR revealed differential expression of genes associated with leaf polarity regulation and the IAA signaling pathway between WT and clm1. Our results identified BrCLF as a key regulator of leaf curling in Chinese cabbage.