1-Hydroxyphenazine Targets PLP-Dependent Transferase to Control Corynespora Target Spot

Area of Science:

• Agricultural Science
• Plant Pathology
• Mycology

Background:

• Corynespora leaf spot, caused by *Corynespora cassiicola*, is an emerging crop disease with increasing fungicide resistance.
• Effective control strategies and novel fungicides are urgently needed to manage this pathogen and preserve crop yield and quality.

Purpose of the Study:

• To evaluate the antifungal activity of 1-hydroxyphenazine (1OH-PHZ) against *C. cassiicola*.
• To elucidate the mode of action of 1OH-PHZ in inhibiting fungal growth.

Main Methods:

• In vitro and in vivo antifungal assays were conducted.
• Microscopic and ultrastructural analyses were performed.
• Integrated transcriptomic and metabolomic analyses, molecular docking, dynamic simulations, and microscale thermophoresis were employed.

Main Results:

• 1OH-PHZ exhibited significant antifungal activity against *C. cassiicola* hyphae (EC50 = 19.23 μg/ml) and in detached tomato leaves and fruits.
• Microscopic observations revealed hyphal collapse and membrane damage.
• Analyses indicated that 1OH-PHZ disrupts amino acid metabolism and biosynthesis by binding to PLP-dependent transferase (PLPDT).

Conclusions:

• 1OH-PHZ demonstrates potent fungicidal properties against *C. cassiicola*.
• The compound's mechanism involves inhibiting amino acid metabolism and biosynthesis via PLPDT binding, affecting fungal cell integrity.
• 1OH-PHZ shows promise as a novel agricultural fungicide for managing *C. cassiicola* infections.