Endophytic Burkholderia plantarii BpMS90 protects harvested tomato against gray mold via antagonistic action and disease resistance induction

Gray mold, a highly destructive disease that affects economically significant crops such as tomatoes, has been a subject of considerable research. Biological control via microorganisms is considered safe, effective, and environmentally friendly. Therefore, screening for biocontrol agents against Botrytis cinerea and elucidating their antagonistic mechanisms are essential for the biological management of tomato gray mold. In this study, Burkholderia plantarii BpMS90, which exhibited a 63.51% inhibition rate against B. cinerea and broad-spectrum antifungal activity against 10 plant pathogenic fungi, was isolated from the roots of Potentilla kleiniana. Biochemical, morphological, and genomic analyses classified BpMS90 as a strain of B. plantarii. Microscopic examination revealed that BpMS90 inhibited B. cinerea hyphae growth and markedly suppressed B. cinerea spore germination. Needle inoculation assays revealed that BpMS90 mitigates tomato fruit gray mold disease symptoms. Transcriptomic analysis and quantitative reverse transcription polymerase chain reaction demonstrated that BpMS90 induces the upregulation of disease resistance-associated genes, such as RPM1, RPS2, and PIK1 within the Avr-mediated defense pathway. BpMS90 reduces the relative abundance of B. cinerea in postharvest tomato fruit and mitigates rot diseases caused by this fungus during storage by inducing the upregulation of genes involved in Avr-mediated defense pathways. This study is the first to reveal the biocontrol potential of BpMS90, thereby laying a foundation for B. cinerea control strategies and offering valuable insights into the postharvest biological control of fruits.