Trans‐2‐pentenal suppresses potato common scab via dual inhibition of thiamine and energy metabolism in Streptomyces scabies

BACKGROUND Potato common scab, a devastating soil‐borne disease caused by Streptomyces scabies and other pathogenic Streptomyces species. Resistant cultivar Longshu 27 and susceptible Longshu 20 were used. Volatile organic compounds (VOCs) with direct antibacterial activity in potato tubers were identified and screened through HS‐SPME‐GC–MS and in vitro antibacterial assays. The antibacterial mechanisms of characteristic VOCs from the resistant cultivar were elucidated through transcriptome sequencing and validation experiments. RESULTS Trans‐2‐pentenal, which was significantly higher in the disease resistant variety than in the susceptible variety, exhibited strong inhibitory effects on S. scabies and S. enissocaesilis . The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 313 and 625 μg·mL −1 , respectively. Treatment with trans‐2‐pentenal suppressed S. scabies and S . enissocaesilis virulence, restoring radish seedling height to normal levels and causing shrinkage and distortion of the S. scabies mycelial surface. Additionally, it significantly inhibited the activities of ATPase and respiratory chain dehydrogenase in S. scabies and downregulated key genes ( thiC , thiO , dxs , thiG ) in the thiamine metabolism pathway, leading to a 54.3% reduction in intracellular thiamine content. Exogenous thiamine supplementation partially reversed the antibacterial effect, confirming thiamine metabolism as a critical target. Pot trials showed that root irrigation with trans‐2‐pentenal reduced the potato common scab disease index by 50.84%. CONCLUSION This study is the first to demonstrate that VOCs from resistant potato cultivars exert antibacterial effects by disrupting pathogen energy metabolism and thiamine biosynthesis, providing a theoretical foundation for developing novel plant volatile‐based biocontrol strategies.