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

Author: mycolabadmin
10/31/2025
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Summary

Scientists discovered beneficial bacteria living on ash and pine trees that can fight two major forest diseases: ash dieback and needle cast. These bacteria not only kill the harmful fungi but also help trees grow stronger by improving nutrient absorption. This research offers promise for protecting European forests without relying on chemical fungicides, creating a more natural and sustainable approach to forest health.

Background

Needle cast caused by Lophodermium seditiosum and ash dieback caused by Hymenoscyphus fraxineus are destructive forest diseases in Europe threatening Scots pine and European ash. Conventional fungicide treatments have limited effectiveness and practical application at large scales. Microbial biocontrol agents with dual antagonistic and plant growth-promoting traits offer promising sustainable alternatives for forest disease management.

Objective

To isolate and characterize native bacterial antagonists from European ash and Scots pine tissues and evaluate their efficacy against respective pathogens while assessing plant growth-promoting traits. The study aimed to fill a significant research gap regarding biocontrol of needle cast and to provide comparative assessment of host-derived microbial antagonists for integrated forest protection strategies.

Results

Twelve bacterial isolates from ash (genera Pantoea, Erwinia, Pseudomonas, Priestia, Curtobacterium, Staphylococcus) inhibited H. fraxineus growth by ≥70%, while three bacterial isolates from Scots pine (Pseudomonas, Bacillus, Priestia) inhibited L. seditiosum growth by 50-80%. All isolates displayed multiple plant growth-promoting traits, with organic phosphate mineralization and siderophore production being most prevalent. Pantoea agglomerans, Erwinia rhapontici, and Priestia aryabhattai from ash showed particularly strong antagonistic potential.

Conclusion

Native bacterial isolates from European ash and Scots pine demonstrated promising dual functionality as biocontrol agents and plant growth promoters. The findings represent significant progress in developing eco-friendly management strategies for ash dieback and particularly for the neglected needle cast pathosystem. Further in planta and field studies are needed to validate efficacy and clarify specific mechanisms of pathogen inhibition.

Published in:Microorganisms,
Study Type:In vitro experimental study,
Source: PMID: 41304203, DOI: 10.3390/microorganisms13112517