Functional characterization of BoVML1 uncovers a RER3-related network controlling chloroplast development and leaf...

Area of Science:

• Plant genetics and molecular biology
• Crop science
• Photosynthesis research

Background:

• Leaf color and morphology in cabbage (Brassica oleracea var. capitata) are crucial for yield, photosynthesis, and market quality.
• A natural mutant (1180mu) with virescent-malformed leaves, reduced fertility, and impaired growth was identified.

Purpose of the Study:

• To identify the genetic basis of the virescent-malformed leaf phenotype in cabbage mutant 1180mu.
• To elucidate the function of the causal gene in chloroplast development and plant morphogenesis.

Main Methods:

• Map-based cloning and CRISPR/Cas9 gene editing were used to identify and validate the causal gene, BoVML1.
• Physiological analyses, transcriptomic profiling, and protein interaction assays (Y2H, Co-IP) were performed.

Main Results:

• A 44-bp deletion in the dominant gene BoVML1 was identified as the cause of the mutant phenotype.
• BoVML1 knockout mimicked the mutant phenotype, while complementation restored normal traits.
• BoVML1 is chloroplast-targeted and interacts with stress-response-associated proteins BoPMD1 and BoNAC62.
• Transcriptomic analysis revealed broad transcriptional reprogramming in secondary metabolism, phenylpropanoid, and hormone signaling pathways.

Conclusions:

• BoVML1 is a key positive regulator of chloroplast development, leaf color, and leaf morphology in cabbage.
• The study provides a mechanistic understanding and a genetic target for improving leaf traits in Brassica breeding programs.