As global climate change intensifies and agricultural environments become increasingly arid, understanding the adaptive mechanisms of terrestrial plants is critical for global food security. Plant cuticular wax forms a vital hydrophobic barrier that protects crops from severe water loss, UV radiation, and pathogen infection. Sorghum ( Sorghum bicolor (L.) Moench), a major drought-tolerant crop, is valued for its thick cuticular wax layer, which markedly enhances resilience to abiotic stresses. However, the key regulatory mechanisms governing cuticular wax accumulation and very-long-chain fatty acid (VLCFA) biosynthesis have remained largely uncharacterized.
To address these gaps, a research team led by Prof. Hongwei Cai and Assoc. Prof. Jun Chen from China Agricultural University identified a novel bloomless mutant, bm-sz , and cloned its causal gene, BM-SZ , revealing a new regulatory network underlying sorghum wax biosynthesis. The study was published online in The Crop Journal .
"Using ethyl methane sulfonate (EMS) mutagenesis, we isolated the bm-sz mutant, which showed an approximately 80% reduction in total wax content and severe drought sensitivity," explained first author Candong Xiong. "Through map-based cloning and MutMap analysis, we confirmed that BM-SZ , which encodes a putative α/β hydrolase, is the causal gene for the bloomless phenotype."
The main findings are as follows:
Furthermore, the team performed haplotype analysis using 659 sorghum accessions. "We found that BM-SZ is highly conserved across sorghum germplasm, with no natural loss-of-function variants detected in the examined population, highlighting its essential and irreplaceable role in epicuticular wax formation during sorghum evolution," says Cai.
The structural and transcriptomic analyses suggest that BM-SZ may have dual functions: acting not only as a metabolic enzyme but also potentially as a signaling receptor. "Mutations in the catalytic pocket likely disrupt a key signaling cascade, leading to the transcriptional repression of the entire wax biosynthetic pathway," adds Cai.
This discovery clarifies the functions and regulatory modes of the α/β hydrolase family in sorghum, providing a valuable genetic target and theoretical basis for molecular breeding of high-drought-tolerance crops.
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Contact the author: Hongwei Cai ( caihw@cau.edu.cn ) & Jun Chen (chenj@cau.edu.cn)
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The Crop Journal
Experimental study
Not applicable
The BM-SZ gene encoding an α/β hydrolase is essential for wax accumulation in sorghum
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.