Effects of nitric oxide on growth of Fusarium sulphureum and its virulence to potato tubers

The antifungal activity of nitric oxide (NO) on Fusarium sulphureum in vitro and curative or preventive efficacy against dry rot in potato tubers was studied. We report that NO released by sodium nitroprusside (SNP) aqueous solution strongly inhibited spore germination and mycelial growth of F. sulphureum in a concentration-dependent manner. When treated with SNP, the fungus, under scanning electron microscopy, appeared distorted with irregular hyphal growth. Transmission electron microscopy observations documented further ultrastructural alterations of hyphae treated with SNP, and these changes included abnormally contracted, distorted hyphal cell walls, large empty cavities in the cytoplasm and even malformed hyphae. Furthermore, SNP was effective at curing and preventing dry rot in potato tubers in vivo. These findings highlight NO as a promising natural fungicide that could partially substitute for the utilization of synthetic fungicides in potato tubers.