Controlling Tomato Fusarium Wilt Disease through Bacillus thuringiensis-Mediated Defense Primining.

Background: Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. lycopersici (Fol) (Sacc.) W.C. Snyder and H.N. Hans is one of the most prevalent and devastating diseases of tomato plants (Solanum lycoprsicum L.) that leads to a severe reduction in crop yield almost worldwide.

Objective: Evaluation of biocontrol potential of Bacillus thuringiensis (Bt) isolate IBRC-M11096, against Fol in tomato through primin.

Materials and methods: qRT-PCR technique was applied to analyze the effect of the strain on the hormonal defensive pathways; transcriptional responses of jasmonic acid (COI1, Pin2) and salicylic acid (NRP1 and PR1) pathway genes in Bt-treated plants following inoculation of Fol as compared to the plants only challenged with Fol. Also, the potential of the bacterial strain as a biocontrol agent was studied by evaluating growth indices and area under disease progress curve (AUDPC).

Results: The transcription of both defensive hormonal pathway genes (COI1, Pin2, NPR1, PR1) increased due to bacterial priming. The bacterial priming reduced the AUDPC compared to the inoculation with only Fol. The strain reduced the disease symptoms, and compared to the plants only challenged with the fungus, the bacterial strain significantly raised shoot dry and fresh weights and root dry weight.

Conclusion: Priming with the Bt strain led to improved shoot and root growth indices, reduced AUDPC, and fortified responses of both JA and SA hormonal pathways. However, further full-span studies are required to judge the efficacy of the bacterial strain in the biological control of tomato fusarium wilt under field conditions.