Biocontrol of Botrytis cinerea on Tomato Leaves and Growth Promotion Potential of Soil Isolate HJ505 (Burkholderia ambifaria)

Background and Objective: Due to the warm and humid weather in glasshouse or open field in West-Africa, tomato culture is exposed to phytopathogens like Botrytis cinerea causing tomato seedlings damping-off, leaves lesions and fruits rot. In this study, Japan soil bacteria HJ505 was evaluated for Botrytis cinerea biocontrol and tomato growth promotion. Materials and Methods: Dual culture technic was used to evaluate HJ505 inhibitory effect on various pathogens, and microscopy counting used for Botrytis cinerea conidia inhibition. Spray technic was used for home Momotaro tomato leaves inoculation, 16S rDNA analyzed for HJ505 identification, disc diffusion used for protease and siderophores production test. HJ505 cells were observed on electron microscopy and volatile compounds production evaluated on divided sealed plates. IAA production by HJ505 was tested using colorimetric method, and broth poisoning technic was used for salinity and acidity tolerance test. Statistical analysis was performed using Student’s t-test (two groups), one-way ANOVA followed by Tukey’s HSD test (multiple groups), with data presented as Mean±SD and significance considered at p<0.05 Results: Isolate HJ505 PC1 broth strongly inhibited on plates Botrytis cinerea and 5 others tomato fungal pathogens. HJ505 LB broth and filtrate inhibitory effect on pathogen conidial germination were also confirmed. On tomato plants, HJ505 LB broth and filtrate significantly reduced pathogen Botrytis cinerea necrotic lesions on leaves. HJ505, identified as Burkholderia ambifaria, shared the rod shape of Burkholderia species cells, produced protease and volatile compounds. HJ505 promoted tomato seedling growth, produced siderophores, IAA and was tolerant to pH and salinity variation. Conclusion: HJ505 can be considered as a good candidate for Botrytis cinerea biocontrol and tomato growth promotion.