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

Area of Science:

• Agricultural Science
• Plant Pathology
• Biochemistry

Background:

• Rice blast, caused by Magnaporthe oryzae, is a major threat to global rice production and food security.
• Intercropping rice varieties is a promising strategy for disease control, but the underlying mechanisms involving root interactions are not fully understood.

Purpose of the Study:

• To investigate the role of root interactions and root exudates in mediating rice blast resistance during intercropping.
• To identify specific metabolites involved in inducing defense responses in rice.

Main Methods:

• Field and greenhouse experiments involving intercropping of susceptible and resistant rice varieties.
• Transcriptome and metabolome profiling of root exudates.
• Correlation analysis to link metabolites with resistance-regulating genes.
• Functional validation of identified compounds.

Main Results:

• Intercropping enhanced disease resistance in both rice varieties, mediated by root-secreted metabolites that activated defense pathways.
• Metabolome profiling revealed changes in root exudates, with enrichment in flavonoid/phenylpropanoid biosynthesis and antifungal compounds.
• Four core compounds—azelaic acid (AzA), sebacic acid (SA), betaine (Bet), and phenyl acetate (PhAc)—were identified and linked to resistance.

Conclusions:

• Intercropping induces resistance in rice, even in susceptible varieties, through key root exudates.
• Azelaic acid and sebacic acid directly inhibited Magnaporthe oryzae growth.
• These findings elucidate the mechanisms of rice blast resistance in intercropping systems, highlighting the importance of root metabolite signaling.