Trichoderma spp. are well-known biocontrol agents because of their antimicrobial activity against bacterial and fungal phytopathogens. However, the biochemical mechanism of their antiviral activity remains largely unknown. In this study, we found that Trichokonins, antimicrobial peptaibols isolated from Trichoderma pseudokoningii SMF2, could induce defense responses and systemic resistance in tobacco (Nicotiana tabacum var. Samsun NN) against tobacco mosaic virus (TMV) infection. Local Trichokonin (100 nM) treatment led to 54% lesion inhibition, 57% reduction in average lesion diameter and 30% reduction in average lesion area in systemic tissue of tobacco compared with control, indicating that Trichokonins induced resistance in tobacco against TMV infection. Trichokonin treatment increased the production of reactive oxygen species and phenolic compounds in tobacco. Additionally, application of Trichokonins significantly increased activities of pathogenesis-related enzymes PAL and POD, and upregulated the expression of several plant defense genes. These results suggested that multiple defense pathways in tobacco were involved in Trichokonin-mediated TMV resistance. We report on the antivirus mechanism of peptaibols, which sheds light on the potential of peptaibols in plant viral disease control.

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Summary Rhizobacteria devote a relatively large percentage of their genomes to encode bioactive natural products that are important for competition in the rhizosphere. In this study, a plant beneficial rhizobacterium Bacillus velezensis SQR9 was discovered to produce novel antibacterial fatty acids, Bacillunoic acids, which are encoded on a genomic island (GI). This GI contains a hybrid type I fatty acid synthase (FAS)‐polyketide synthase (PKS) system and an ABC transporter. The FAS was predicted to synthesize a primer that was transferred to the PKS to synthesize Bacillunoic acids. The synthesized Bacillunoic acids inhibit the growth of diverse bacteria, with the strongest activity against closely related Bacillus strains, the ABC transporter exported the toxic Bacillunoic acids upon their induction for protecting the producing strain. The inhibition of other Bacillus strains by Bacillunoic acids extended the antimicrobial spectrum of SQR9 and enhanced its competition with closely related root‐associated bacteria. So, through the obtaining of this GI by horizontal gene transfer, strain SQR9 not only acquired a competitive weapon but also acquired a self‐protecting shield, which increased its competition with other rhizobacteria.

Patulin contamination of fruit- and vegetable-based products had become a major challenge for the food industry. Biological methods of patulin control can play an important role due to their safety and high efficiency. In this study, a strain of marine yeast with high patulin degradation ability was screened. The yeast was identified as Kodameae ohmeri by the BioLog identification system and partial 26S rRNA gene sequencing. The degradation products of patulin were identified as (E)- and (Z)-ascladiol through HPLC and LC-TOF/MS. High patulin tolerance at 100 μg ml(-1) and a high degradation rate at 35°C at a pH between 3 and 6 indicates the potential application of K. ohmeri for patulin detoxification of apple-derived products.