Transcriptomic Analysis and Biocontrol Potential of <i>Bacillus velezensis</i> T25 against Fusarium Wilt of Banana

Fusarium wilt of banana (FWB)-a soil-borne disease caused by Fusarium oxysporum f. sp. cubense (Foc), particularly the tropical race 4 (TR4)-poses a significant threat to the banana industry. The strain Bacillus velezensis T25 has been shown to significantly inhibit the growth of Foc TR4. In dual culture plates, strain T25 exhibited strong inhibition of mycelial growth and induced hyphal wrinkles, ruptures, and deformities in vitro cultures. In pot experiments conducted in a greenhouse, treatment with T25 resulted in an 84.21% reduction in the disease incidence among banana seedlings. Furthermore, T25 treatment significantly enhanced the accumulation of hydrogen peroxide (H₂O₂) and callose within banana leaves while markedly increasing the activities of key defense-related enzymes such as superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL). To analyze the effects of strain T25 on banana plants before and after treatment, comparative transcriptome analysis was performed RNA sequencing (RNA-seq) analysis following T25 treatment revealed 882 differentially expressed genes (DEGs) when compared to control samples. Among the genes, 303 genes were up-regulated, and 579 genes were down-regulated. Notably, key upregulated defense-associated genes comprise PR1, GLT1, PTI6, and IAA, among others. These findings demonstrate that B. velezensis T25 can be utilized as a viable option for managing FWB through the induction systemic resistance, underscoring its significant potential as a biocontrol agent against this devastating disease.