Secondary Metabolites of Pseudomonas aeruginosa LV Strain Decrease Asian Soybean Rust Severity in Experimentally...

Area of Science:

• Plant Pathology
• Microbiology
• Biotechnology

Background:

• Asian Soybean Rust (ASR), caused by *Phakopsora pachyrhizi*, leads to substantial yield losses (up to 90%).
• Fungicide resistance in *P. pachyrhizi* necessitates alternative ASR management strategies.
• Activating plant defense mechanisms presents a viable approach for ASR control.

Purpose of the Study:

• To investigate the efficacy of *Pseudomonas aeruginosa* LV strain's secondary metabolites against *Phakopsora pachyrhizi*.
• To assess the impact of these metabolites on fungal spore germination and soybean defense gene expression.
• To evaluate the potential of these metabolites as bio-control agents for ASR.

Main Methods:

• In vitro testing of F4A fraction and pure metabolites on *P. pachyrhizi* spore germination.
• Analysis of defense-related gene expression (PAL, OMT, PR-2) in soybean plants post-treatment.
• Greenhouse trials evaluating ASR severity and lesion frequency in treated soybean plants.

Main Results:

• The F4A fraction significantly reduced spore germination, with 100 µg mL⁻¹ achieving complete inhibition.
• Treatment with an organocopper antimicrobial compound (OAC) induced overexpression of key defense genes (PAL, OMT, PR-2).
• PCA (60 µg mL⁻¹) and F4A (2 and 20 µg mL⁻¹) significantly reduced ASR severity and lesion frequency in greenhouse conditions.

Conclusions:

• Secondary metabolites from *Pseudomonas aeruginosa* LV strain demonstrate potent antifungal activity against *Phakopsora pachyrhizi*.
• These metabolites effectively inhibit spore germination and reduce ASR incidence in soybean plants.
• The findings suggest these metabolites are promising bio-control agents for managing Asian Soybean Rust.