Biocontrol Efficacy of Pseudomonas Consortia Against Botrytis Blight in Petunias

Botrytis cinerea, a fungal pathogen causing Botrytis blight, significantly impacts greenhouse crop management due to its broad host range and infection capabilities at various growth stages. Traditional control methods, primarily reliant on fungicides, are challenged by environmental concerns and the rise of fungicide-resistant strains. This study investigates the use of beneficial Pseudomonas bacteria as a sustainable alternative. We hypothesized that specific Pseudomonas consortia could provide more effective biocontrol of B. cinerea than individual strains. Our research investigated five Pseudomonas strains (14B11, AP54, 15H3, 94G2, and 89F1) known to reduce Botrytis blight in Petunia × hybrida. Compatibility for bacterial consortia was assessed through biofilm formation and direct bacterial inhibition assays. The biocontrol effects of the bacteria against B. cinerea were investigated in vitro using shared-air space dual culture assays and in planta by inoculating detached petunia flowers. We found strain 14B11 exhibited the highest biofilm formation, with consortia of 14B11 and 89F1 showing significant enhancement compared to individual cultures, while a slight, non-significant increase was observed in 14B11 and AP54 consortia. However, strain 14B11 efficacy was inhibited by strain 15H3. Genomic analyses identified antifungal compound-related gene clusters in 14B11 and AP54, contributing to their biocontrol potential. Trials with detached flowers of Petunia × hybrida ‘Carpet Red Bright’ confirmed significant disease severity reduction with 14B11, AP54, and their consortia. This research highlights strategic Pseudomonas consortia as promising, eco-friendly alternatives to chemical fungicides, promoting sustainable agriculture by enhancing our understanding of how microbial interactions can be used to manage Botrytis blight.