Biocontrol Ability and Mechanism of a Broad-Spectrum Antifungal Strain sp. QN1NO-4 Against Strawberry Anthracnose Caused by .

Strawberry is a very popular fruit with a special taste, color, and nutritional value. Anthracnose caused by severely limits fruit shelf life during post-harvest storage. Use of traditional chemical fungicides leads to serious environment pollution and threatens food safety. Biocontrol is considered as a promising strategy to manage the post-harvest fruit diseases. Here, strain QN1NO-4 isolated from noni ( L.) fruit exhibited a high antifungal activity against . Based on its physicochemical profiles and phylogenetic tree of the 16S sequence, strain QN1NO-4 belonged to the genus . The average nucleotide identity (ANI) calculated by comparing two standard strain genomes was below 95-96%, suggesting that the strain might be a novel species of the genus and named as sp. QN1NO-4. Its extract effectively reduced the incidence of strawberry anthracnose of harvested fruit. Fruit weight and TSS contents were also maintained significantly. The antifungal mechanism assays indicated that the extract of the test antagonist inhibited mycelial growth and spore germination of Cells of strain QN1NO-4 demonstrated the cytoplasmic heterogeneity, disappeared organelles, and ruptured ultrastructure. Notably, the strain extract also had a broad-spectrum antifungal activity. Compared with the whole genome of strain QN1NO-4, several functional gene clusters involved in the biosynthesis of active secondary metabolites were observed. Fifteen compounds were identified by gas chromatography-mass spectrometry (GC-MS). Hence, the fruit endophyte sp. QN1NO-4 is a potential bio-agent identified for the management of post-harvest disease of strawberry fruit.