Potential Biocontrol Activities of Populus Endophytes against Several Plant Pathogens Using Different Inhibitory...

Area of Science:

• Plant Pathology
• Microbiology
• Agricultural Science

Background:

• The plant microbiome, particularly endophytes, can enhance plant defense against biotic and abiotic stresses.
• Endophytes can directly inhibit plant fungal pathogens, offering a sustainable approach to crop protection.
• Wild poplar endophytes represent an underexplored resource for discovering novel biocontrol agents.

Purpose of the Study:

• To isolate and characterize novel endophytic strains from wild poplar with antifungal activity against key agricultural pathogens.
• To investigate the genetic basis of antimicrobial activity in these endophytes.
• To assess other beneficial symbiotic traits relevant to plant health and growth.

Main Methods:

• Development of a direct screening method using dilute wild poplar extracts to identify inhibitory endophytes.
• Isolation and characterization of eleven promising endophytic strains.
• Genomic analysis to identify antimicrobial gene clusters (e.g., bacillomycin, fengicyn, bacillibactin, sessilin, viscosin, tolaasin, occidiofungin).
• Construction and testing of an occidiofungin deletion mutant in *Burkholderia vietnamiensis* WPB.

Main Results:

• Eleven endophyte isolates demonstrated inhibitory activity against at least two plant pathogen strains.
• Newly isolated *Bacillus* strains possess gene clusters for bacillomycin, fengicyn, and bacillibactin.
• *Pseudomonas* strains contained gene clusters for sessilin, viscosin, and tolaasin synthesis.
• The *Burkholderia vietnamiensis* WPB genome harbors the occidiofungin (ocf) gene cluster; an *ocf* deletion mutant showed reduced antifungal activity.
• New isolates lacked the occidiofungin gene cluster, suggesting alternative antimicrobial mechanisms.

Conclusions:

• The wild poplar microbiome is a valuable source of endophytes with significant antifungal potential.
• Identified endophytes exhibit diverse antimicrobial gene clusters and modes of action, suitable for biocontrol applications.
• Further in vivo studies are warranted to evaluate the efficacy of these candidate endophytes against crop diseases.