Biocontrol of tomato pathogens by Bacillus subtilis F62 and its synergistic action in plant growth promotion with Rhizobium sp. L5

ABSTRACT

Plant growth-promoting rhizobacteria (PGPR) are recognised for inhibiting pathogens and increasing plant biomass and yield. This study aims to evaluate the antagonistic potential of Bacillus subtilis F62 against fungal diseases of tomatoes and investigates its capability for promoting the growth of tomato seedlings using single-strain inoculation and co-inoculation with Rhizobium sp. L5. The in vitro antagonism of B. subtilis F62 against Alternaria sp., Botrytis sp., Fusarium sp., and Stemphylium sp. was assessed through dual-culture and volatile compounds assays. Furthermore, the antagonism against Botrytis sp. was also evaluated in harvested tomatoes. The growth promotion experiment involved treating tomato seeds with bacterial suspensions through soil drenching and seed soaking. Our results demonstrated the inhibitory ability of B. subtilis F62 against all fungal species, reducing the mycelial growth speed index from 54.7% to 76.6% in the dual-culture assay, and from 14.1% to 70.6% through antagonism via volatile compounds. This bacterium also decreased the incidence and severity of Botrytis sp. by 21% and 18.8%, respectively, in harvested tomatoes. Additionally, the growth promotion assay revealed that co-inoculation of B. subtilis F62 and Rhizobium sp. L5 increased leaf area and root dry weight compared to single-strain inoculation. Therefore, B. subtilis F62 is a promising bacterium for the biocontrol of tomato diseases and an effective plant growth-promoting rhizobacterium, demonstrating its synergistic effect when co-inoculated with Rhizobium sp. L5 on tomato seeds.

KEYWORDS:

• Biocontrol
• plant growth-promoting rhizobacteria
• Solanum lycopersicum
• bacterial consortium‌

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets generated and analysed during the current study are available in the text.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by the CAPES (Coordination of Superior Level Staff Improvement) under Financial code 001.