Tackling Conifer Needle Cast and Ash Dieback with Host-Derived Microbial Antagonists Exhibiting Plant Growth-Promoting Traits

Summary

Scientists discovered native bacteria from European ash and Scots pine trees that can fight two destructive forest diseases: ash dieback and needle cast. These bacteria not only inhibit the disease-causing fungi but also help trees grow better by improving nutrient uptake. This natural approach offers an eco-friendly alternative to fungicide sprays for protecting forests.

Background

Needle cast disease caused by Lophodermium seditiosum and ash dieback caused by Hymenoscyphus fraxineus are among the most destructive forest diseases in Europe. Conventional management strategies are limited and impractical at large scales, necessitating sustainable alternatives. Microbial antagonists with dual biocontrol and plant growth-promoting properties offer promising eco-friendly solutions for forest disease management.

Objective

To isolate and characterize native bacterial antagonists from European ash and Scots pine, evaluate their efficacy against respective pathogens through in vitro assays, and assess their plant growth-promoting traits. This study addresses a significant gap in comparative investigations of native bacterial isolates for biocontrol against both pathogens.

Results

Twelve bacterial isolates from ash inhibited H. fraxineus growth by ≥70%, including Pantoea, Erwinia, Pseudomonas, and Priestia species. Three isolates from Scots pine inhibited L. seditiosum growth by 50-80%, with Bacillus velezensis showing 80% inhibition. All isolates demonstrated multiple plant growth-promoting traits, primarily organic phosphate mineralization and siderophore production.

Conclusion

Native bacterial isolates from European ash and Scots pine exhibit promising dual biocontrol and plant growth-promoting potential. These findings represent significant progress toward eco-friendly management of ash dieback and needle cast diseases. Further in planta and field studies are needed to confirm efficacy and elucidate pathogen inhibition mechanisms.
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