Integrated transcriptomic and phenotypic analysis reveals the multi-target antibacterial mechanism of sulforaphane against Xanthomonas oryzae pv. oryzicola.

Plant pathogenic bacteria represent a significant threat to global crop production, thereby necessitating the development of novel and sustainable bactericides. Sulforaphane (SFN), a natural isothiocyanate derived from cruciferous vegetables, is known to possess diverse biological activities including antimicrobial properties. This study provides a comprehensive evaluation of the antibacterial efficacy and underlying mechanisms of SFN against Xanthomonas oryzae pv. oryzicola (Xoc), the pathogen responsible for rice bacterial leaf streak. In vitro assays demonstrated that SFN possesses broad-spectrum activity against 12 plant pathogens, with particularly high efficacy against Xoc, as evidenced by an EC₅₀ value of 5.47 μg/mL. In vivo pot experiments indicated that SFN at 100 μg/mL offered both protective (57.91%) and curative (56.70%) control against the disease, surpassing the effectiveness of thiadiazole copper and comparable to that of kasugamycin. Physiological and biochemical analyses revealed that SFN compromised cell membrane integrity, disrupted flagellar structure and motility, and reduced extracellular polysaccharide production and biofilm formation dose-dependently. Integrated transcriptomic and phenotypic analyses revealed that SFN consistently inhibited the oxidative phosphorylation pathway, resulting in reduced ATP levels, increased ROS accumulation, and ultimately impaired energy metabolism and membrane potential. Simultaneously, it downregulated flagellar assembly and associated pathways. These findings indicate that SFN exerts significant antibacterial effects against Xoc through a synergistic multi-target mechanism that involves the disruption of energy metabolism and suppression of virulence. This work not only provides an in-depth understanding of SFN's action mode but also positions it as a highly promising, natural lead compound for developing eco-friendly bactericides.