Discovery of Niphimycin C from Streptomyces yongxingensis sp. nov. as a Promising Agrochemical Fungicide for Controlling Banana Fusarium Wilt by Destroying the Mitochondrial Structure and Function.

Banana wilt caused by f. sp. () is the most destructive soil-borne fungal disease. Tropical race 4 ( TR4), one of the strains of , can infect many commercial cultivars, which represents a threat to global banana production. Currently, there are hardly any effective chemical fungicides to control the disease. To search for natural product-based fungicides for controlling banana wilt, we identified a novel strain sp. nov. (JCM 34965) from a marine soft coral, from which a bioactive compound, niphimycin C, was isolated using an activity-guided method. Niphimycin C exhibited a strong antifungal activity against TR4 with a value of 1.20 μg/mL for EC and obviously inhibited the mycelial growth and spore germination of TR4. It caused the functional loss of mitochondria and the disorder of metabolism of TR4 cells. Further study showed that niphimycin C reduced key enzyme activities of the tricarboxylic acid (TCA) cycle and the electron transport chain (ETC). It displayed broad-spectrum antifungal activities against the selected 12 phytopathogenic fungi. In pot experiments, niphimycin C reduced the disease indexes in banana plantlets and inhibited the infection of TR4 in roots. Hence, niphimycin C could be a promising agrochemical fungicide for the management of fungal diseases.