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Rice varietal intercropping mediates resistance to rice blast (Magnaporthe oryzae) through core root exudates

Summary

Growing different varieties of rice together can help protect susceptible rice plants from blast disease. When resistant and susceptible rice varieties are planted together, the resistant plants release special chemicals from their roots that help the susceptible plants fight off the fungal disease. Scientists identified four key chemicals—azelaic acid, sebacic acid, betaine, and phenyl acetate—that work together to boost the immune system of susceptible rice plants and directly kill the blast fungus.

Background

Rice blast caused by Magnaporthe oryzae is a major threat to global rice production, causing yield losses up to 80%. Varietal intercropping has demonstrated effectiveness in controlling rice blast, but the role of root metabolites in mediating this resistance remains unclear. This study investigates the molecular mechanisms by which intercropping susceptible and resistant rice varieties enhances disease resistance through root-secreted metabolites.

Objective

To identify optimal rice varietal combinations for blast resistance and elucidate the mechanisms by which intercropping enhances disease resistance through root metabolites and gene expression changes. The study aims to characterize core root exudates that activate defense pathways in susceptible varieties when grown with resistant varieties.

Results

Intercropping significantly reduced rice blast incidence (46.70-73.27% control efficacy) with the Huangkenuo//Shanyou63 combination showing superior performance. Metabolome profiling identified 224-363 differential metabolites with enrichment in flavonoid and phenylpropanoid biosynthesis pathways. Four core metabolites were identified: azelaic acid, sebacic acid, betaine, and phenyl acetate, which showed positive correlations with disease resistance genes and inhibited M. oryzae growth in vitro and in vivo.

Conclusion

Rice varietal intercropping enhances resistance to blast through root-secreted metabolites that activate defense pathways in susceptible varieties. Core metabolites including azelaic acid and sebacic acid directly inhibit pathogen growth while also upregulating immune-related genes. These findings provide theoretical support for developing eco-friendly, sustainable rice blast management strategies through intercropping systems.
  • Published in:BMC Plant Biology,
  • Study Type:Field Trial and Experimental Study,
  • Source: 10.1186/s12870-025-07724-y, PMID: 41444523
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