MYCOLab Ai Logo - gold and army green

Ectomycorrhizal fungi recruit hyphae-associated bacteria that metabolize thiamine to promote pine symbiosis

Summary

Pine trees partner with special fungi that help them absorb nutrients from soil. However, these fungi sometimes lack vitamin B1 (thiamine) needed for growth. Researchers discovered that these fungi recruit helpful bacteria that produce thiamine, creating a three-way partnership. When all three partners work together, pine seedlings grow much better, showing how nature uses teamwork to help plants thrive in forests.

Background

Ectomycorrhizal fungi form symbiotic relationships with terrestrial plants but some cannot effectively obtain or synthesize thiamine, an essential cofactor for growth. Hyphae-associated bacteria play vital roles in promoting nutrient absorption and ectomycorrhizal root formation. This study investigates how specific bacteria support thiamine acquisition in ectomycorrhizal fungi.

Objective

To elucidate the colonization characteristics of hyphae-associated bacterium Bacillus altitudinis B4 on ectomycorrhizal fungus Suillus clintonianus and to determine the synergistic mechanisms by which B. altitudinis promotes thiamine synthesis and absorption by the fungus.

Results

S. clintonianus is thiamine auxotrophic, lacking key biosynthesis genes but retaining thiamine transporters. The fungus recruits B. altitudinis B4 through secretion of ureidosuccinic acid and pregnenolone. B. altitudinis B4 significantly increases thiamine production when co-cultured with the fungus, with upregulated expression of thiamine metabolism genes. In pot experiments, the combined treatment significantly enhanced ectomycorrhizal colonization rates and seedling growth parameters.

Conclusion

This study demonstrates that ectomycorrhizal fungi acquire thiamine through cross-kingdom partnership with specialized bacteria. The selective recruitment of B. altitudinis B4 via fungal metabolites and subsequent enhanced thiamine production reveal a sophisticated mutualistic mechanism that promotes ectomycorrhizal symbiosis and plant growth.
  • Published in:ISME Journal,
  • Study Type:Experimental Study,
  • Source: PMID: 41454778, DOI: 10.1093/ismejo/wraf290
Scroll to Top