Fusarium dry rot is one of the major potato diseases during storage after harvest, which not only results in quality degradation but also causes great economic losses. The disease can be elicited by some species of Fusarium, and the pathogenic fungi of Fusarium causing potato dry rot are considerably diverse in various countries and regions. The disease caused by Fusarium spp. is associated with mycotoxins accumulation, which has phytotoxic and mycotoxic effects on humans and animals. Chemical synthetic fungicide is considered the main control measure for the Fusarium dry rot of potato; nevertheless, it is unfortunate that persistent application inevitably results in the emergency of a resistant strain and environmental contamination. A comprehensive disease control strategy includes potato cultivar selection, appropriate cultural practices (crop rotation, cultivate pattern, fertilization, and irrigation), harvesting processes and postharvest treatments (harvesting, classification, packaging, wound healing), and storage conditions (environmental disinfection, temperature, humidity and gas composition) along with the application of fungicide pre-harvest or post-harvest. Recently, emerging studies have indicated that eco-friendly strategies include physical control, chemical methods (such as the application of generally-recognised-as-safe (GRAS) compounds or chemical (elicitors) and biological control have been introduced to combat the Fusarium dry rot of potato.

Penicillium expansum is the predominant causal agent causing blue mold in postharvest fresh Codonopsis pilosula during storage. The pathogen reduces the yield and affects the quality of C. pilosula and even generates patulin, threatening human health. In this study, postharvest fresh, healthy C. pilosula was sprayed with P. expansum, and the control effect of ozone on postharvest diseases of C. pilosula was studied, and the effect of ozone on the contents in the main active ingredients of C. pilosula was compared; finally, the effect of ozone on reactive oxygen species (ROS) metabolism in C. pilosula was analyzed. The results showed that 2 mg L⁻¹ ozone application significantly inhibited the occurrence of postharvest blue mold caused by P. expansum, reduced weight loss rate, controlled the accumulation of patulin and maintained the contents of the main active components in C. pilosula. The study will provide a theoretical basis for ozone treatment to control the occurrence of postharvest diseases of C. pilosula.

Ambient pH, an important environmental factor, affects the growth, pathogenicity, and mycotoxin production of pathogenic fungus. Fusarium sulphureum is one of the predominant causal agents causing fusarium rot of muskmelon. In this study, we investigated the effects of ambient pH on fusarium rot development and diacetoxyscirpenol (DAS) accumulation in muskmelon infected with F. sulphureum, then analyzed the possible mechanisms in vitro and in vivo. The results suggested that ambient pH 6 was more conducive to the growth, pathogenicity, and mycotoxin production of F. sulphureum in vitro. Ambient pH 6 was also more favorable for secretion of cell wall-degrading enzymes for the pathogen to degrade the cell wall of the host plant and up-regulated the relative expression of genes involved in DAS biosynthesis, thus aggravating fruit disease and DAS accumulation. However, when the pH of the inoculated spore suspension was too acidic or too alkaline, the opposite results were observed.

Radix astragali is a homologous plant of medicine and food with a variety of health benefits. However, our previous study showed that blue mold, caused by Penicillium polonicum, is the most important postharvest disease of fresh R. astragali during storage. Ozone, as a strong oxidizing agent, can effectively control the occurrence of postharvest diseases in fruits and vegetables. Nevertheless, there are few research studies on the effect of ozone-treated fresh Chinese traditional medicine. In this study, we investigated the effect of ozone gas on the postharvest blue mold development, mycotoxin accumulation, and main active component contents in fresh R. astragali infected by P. polonicum, and analyzed the possible action mechanism on ROS metabolism. The result indicates that ozone application significantly inhibited the development of postharvest blue mold caused by P. polonicum infection, reduced the disease incidence, disease index, and weight loss rate, maintained the main active ingredients in fresh R. astragali by activating ROS metabolism, enhanced the antioxidant enzymatic activity, thus avoiding oxidative damage caused by excessive ROS accumulation, and maintained the integrity of the cell membrane, ultimately controlling the occurrence of blue mold of R. astragali. Moreover, ozone treatment also maintained the contents of the main active ingredients in R. astragali before 14 d during P. polonicum infection. In addition, the amount of active ingredients of astragaloside I, calycosin-7-glucoside, and ononin in the ozone-treated group was higher than that in the control group during the storage period. We speculate that, under the action of ozone, astragaloside IV was converted into astragaloside II by oxidative modification and astragaloside II was further oxidized to astragaloside I, resulting in the accumulation of astragaloside I. Similarity, the hydrogen atoms (-H) on the benzene ring in formononetin were oxidized to phenolic hydroxyl groups (-OH) to generate calycosin, which was further converted into calycosin-7-glucoside, resulting in calycosin-7-glucoside accumulation. This study will provide the theoretical basis for ozone commercial application to control the occurrence of postharvest diseases of R. astragali.