Comprehensive Genomic Analysis and Evaluation of In Vivo and In Vitro Biocontrol Efficacy of Bacillus velezensis N1 Against Gnomoniopsis smithogilvyi and Neofusicoccum parvum

Canker and dieback diseases caused by fungal pathogens represent an increasing threat to woody plants in both urban and forest environments, where sustainable management options are urgently needed. In this study, the biocontrol potential of Bacillus strain N1 was investigated against Neofusicoccum parvum and Gnomoniopsis smithogilvyi, causal agents of canker diseases on Eucalyptus globulus and Castanea sativa, respectively. The whole-genome sequence confirmed the taxonomic identification of strain N1 as B. velezensis, showing high average nucleotide identity and digital DNA–DNA hybridization values with reference strains. AntiSMASH analysis revealed the presence of multiple biosynthetic gene clusters associated with the production of antimicrobial secondary metabolites, including polyketides, non-ribosomal peptides, and lipopeptides, reflecting strain N1’s genomic potential to produce compounds that may contribute to its antifungal activity. Moreover, B. velezensis strain N1 significantly inhibited the growth of N. parvum and G. smithogilvyi and showed a biocontrol efficacy on detached eucalyptus and chestnut shoots. In both preventive and curative treatments and pathosystems, the application of B. velezensis N1 resulted in a significant reduction in the length of necrotic lesions, compared to pathogen-only controls, while no phytotoxic effects were observed on treated shoots. Overall, this study supported B. velezensis N1 as a promising candidate for the sustainable control of canker-associated pathogens in woody plants.