Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10-As double headed swords to combat Fusarium oxysporum f. sp. lycopersici induced tomato wilt

Wilt disease, caused by Fusarium oxysporum. f. sp. lycopersici, is a global threat to tomato production that needs to be addressed seriously. The current research envisages the use of two self-compatible Bacillus strains, Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10, in a combinatorial approach. The spent supernatant of liquid cultures from strains PKDN31 and PKDL10 showed in vitro antifungal activity against Fusarium sp. attaining an inhibition percentage of 95.33% and 96.54%, respectively. The bacterial isolates lytic activity against Fusarium oxysporum was evaluated by scanning electron microscopic analysis and lytic enzyme pro-duction of amylase, lipase, protease and beta-1,3 glucanase. Furthermore, PKDN31 and PKDL10 produced side-rophores and had root colonizing ability that enhanced the biocontrol efficiency. Combined in vivo inoculation of Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10 on tomato seeds revealed that the strains could induce systemic resistance in tomato against Fusarium oxysporum. f. sp. lycopersici by increasing defence enzymes such as beta-1,3 glucanase, polyphenol oxidase, peroxidase, phenylalanine ammonia-lyase, chitinase, and total phenol accumulations. Pot culture experiments also proved the biocontrol efficacy of the above dual culture supplementation as this treatment displayed a better growth as well as defense against Fusarium challenge compared to the controls. The obtained results suggest that rhizobacterial isolates could be employed as systemic resistance inducers and biocontrol agents in tomato plants to protect against Fusarium wilt disease.

Automated summary

This study investigates the use of two self-compatible Bacillus strains, Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10, in a combinatorial approach to address the global threat of Wilt disease in tomato production. The results show that these strains have inhibitory effects on Fusarium sp. and enhance the defense mechanisms of tomato plants, leading to improved growth and resistance against Fusarium wilt. The efficacy of this dual culture supplementation has been proven in both in vivo and pot culture experiments.