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A tale for two roles: Root-secreted methyl ferulate inhibits P. nicotianae and enriches the rhizosphere Bacillus against black shank disease in tobacco

Summary

Tobacco plants release a natural chemical called methyl ferulate from their roots that has a powerful two-pronged defense against a devastating soil disease called black shank. First, the methyl ferulate directly kills the fungus by disrupting its energy production. Second, it attracts beneficial bacteria called Bacillus to the soil around the roots, which further fight the disease. Scientists found they could boost this defense by engineering a tobacco gene that produces more methyl ferulate, making plants much more resistant to infection. This discovery offers farmers an affordable, natural way to control soil diseases without synthetic chemicals.

Background

Root exudates serve as chemical signaling molecules that regulate rhizosphere interactions and control soil-borne diseases. Methyl ferulate is a naturally occurring antifungal agent used in postharvest pathogen control but not previously studied for plant disease management. The study investigates the role of methyl ferulate, a root exudate, in controlling tobacco black shank disease caused by Phytophthora nicotianae.

Objective

This study aimed to investigate the role of root-secreted methyl ferulate in controlling tobacco black shank disease through both direct pathogen inhibition and indirect mechanisms involving rhizosphere microbiome enrichment. The research sought to elucidate the molecular mechanisms and validate the potential of methyl ferulate as a biocontrol agent.

Results

Methyl ferulate was secreted at higher levels in resistant cultivars and strongly inhibited P. nicotianae (EC50 = 67.51 µg/mL) by disrupting NADH dehydrogenase function and promoting autophagy. Methyl ferulate enriched rhizosphere Bacillus species, particularly Priestia megaterium NM17, which further suppressed pathogen growth. Overexpression of NtCOMT10 gene increased methyl ferulate production by up to 221% and significantly enhanced disease resistance and beneficial microbe recruitment.

Conclusion

Methyl ferulate functions through dual mechanisms: direct inhibition of phytopathogens and recruitment of beneficial Bacillus species. The low cost and effectiveness of methyl ferulate application present a novel and sustainable approach for controlling soil-borne fungal diseases. This research demonstrates the potential of regulating root exudates for holobiont-level plant breeding and disease management.
  • Published in:Microbiome,
  • Study Type:Experimental Research Study,
  • Source: PMID: 39891202, DOI: 10.1186/s40168-024-02008-3
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