Blue mold (penicilliosis) is a common disease of Lanzhou lily (Lilium davidii var. willmottiae) during postharvest storage, which not only seriously affects the appearance and reduces the quality of lily bulbs, but also leads to the accumulation of mycotoxins in rotten lily tissues, seriously endangering human health. Therefore, it is of great significance to clarify the main isolates causing postharvest blue mold of fresh Lanzhou lily and put forward effective measures to control the disease caused by these pathogens. In this study, pathogens were isolated and purified from the naturally diseased blue-mold tissue of Lanzhou lily, and then morphological and molecular biology techniques were applied to identify the isolates, verify the pathogenicity, determine the disease index and disease incidence, and finally, to analyze the control effect of ozone treatment on the blue mold of lily scale and mycotoxin accumulation. The results indicated that the main isolates causing postharvest blue mold of lily were Talaromyces adpressus, Penicillium gladioli, T. calidominioluteus, and P. polonicum. The pathogenicity test showed that P. gladioli and P. polonicum had a higher disease index than T. calidominioluteus and T. adpressus. Ozone treatment significantly reduced the incidence of disease caused by P. gladioli and P. polonicum, and effectively controlled the accumulation of patulin. This study characterized the main pathogens causing blue mold of postharvest Lanzhou lily during storage, and confirmed ozone application has a significant inhibitory effect on blue mold development and patulin accumulation in Lanzhou lily, which could be helpful in commercially controlling blue mold of postharvest Lanzhou lily during storage.

Angelica sinensis, a Chinese herbal medicine, is susceptible to molds during storage, reducing its quality, and even generating mycotoxins with toxic effects on human health. Fresh A. sinensis was harvested from Min County of Gansu Province in China and kept at room temperature. Naturally occurring symptoms were observed during different storage stages. Molds were isolated and identified from the diseased A. sinensis using morphological and molecular biology methods. The impact of ozone treatment on postharvest disease development and mycotoxin production was investigated. The results indicated that A. sinensis decay began on day 7 of storage and progressed thereafter. Nine mold species were isolated and characterized: day 7, two Mucormycetes; day 14, Clonostachys rosea; day 21, two Penicillium species and Aspergillus versicolor; day 28, Alternaria alternata and Trichoderma atroviride; and day 49, Fusarium solani. Ozone treatment markedly inhibited the development of postharvest disease and the mycotoxin production (such as, patulin, 15-acetyl-deoxynivalenol, and sterigmatocystin) in the rotten tissue of A. sinensis inoculated with the nine isolates.

Apple blue mold is a significant postharvest disease caused by Penicillium expansum. pH modification in colonized tissues leads to the production of organic substances, the modulation of enzymes, and then increases fungal pathogenicity. This study evaluated Penicillium expansum-inoculated apple fruits’ quality responding to pH treatments ranging from 2.5 to 8.5 and analyzed the reactive oxygen species (ROS) metabolism modulation in inoculated apple fruits at the same pH. The results showed that the fruit quality of the firmness, total soluble solids, and titratable acid displayed a quick loss at pHs 5.0 and 7.0, compared with 2.5 and 8.5. Similarly, higher disease incidence was observed at pHs 5.0 and 7.0. Apple fruits infected with P. expansum at pHs 2.5 and 8.5 had less content of O₂^•−, H₂O₂, and malondialdehyde (MDA); lower enzymatic activity of NADPH oxidase (NOX); and greater cell membrane integrity than those at pHs 5.0 and 7.0. The analysis of the antioxidant enzymatic activities showed upregulation of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) at pHs 2.5 and 8.5 compared with those at pHs 5.0 and 7.0. Similar trends were shown in ascorbic acid and glutathione. These results support the hypothesis that inoculated apple fruits at pHs 2.5 and 8.5 improve resistance to P. expansum by modulating ROS metabolism, compared with pHs 5.0 and 7.0.

Potato dry rot, caused by Fusarium species, is a devastating fungal decay that seriously impacts the yield and quality of potato tubers worldwide. Fusarium sulphureum is a major causal agent causing potato tuber dry rot that leads to trichothecene accumulation in Gansu Province of China. Ozone (O₃), a strong oxidant, is widely applied to prevent postharvest disease in fruits and vegetables. In this study, F. sulphureum was first treated with 2mgL^-1 ozone for 0, 30s, 1min, and 2min, then inoculated with the potato tubers. The impact of ozone application on dry rot development and diacetoxyscirpenol (DIA) accumulation and the possible mechanisms involved were analyzed. The results showed that ozone treatment significantly inhibited the development of potato tuber dry rot by activating reactive oxygen species (ROS) metabolism and increased the activities of antioxidant enzymes NADPH oxidase (NOX), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) by 24.2, 13.1, 45.4, and 15.8, respectively, compared with their corresponding control. The activities of key enzymes involved in ascorbate-glutathione cycle (AsA-GSH) of ascorbic peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GR) also increased by 26.6, 41.5, 56, and 24.1, respectively, compared with the control group, and their corresponding gene expressions. In addition, ozone treatment markedly suppressed DIA accumulation in potato tubers by downregulating the expression of genes associated with DIA biosynthesis pathway. These results suggest that ozone treatment inhibited the occurrence of potato dry rot and the accumulation of DIA in potato tubers inoculated with F. sulphureum by promoting ROS metabolism and modulating DIA biosynthesis pathway.

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.

Fresh Codonopsis pilosula is highly susceptible to fungus contamination during post-harvest storage, which not only compromises the quality of C. pilosula but also contributes mycotoxin contamination, posing a significant threat to human health. Studies have indicated that ozone treatment can inhibit post-harvest diseases in fruits and vegetables. The impact of ozone treatment on the disease incidence, disease severity index, and weight loss rate of the fresh C. pilosula infected with Actinomucor elegans was investigated through the spray inoculation of A. elegans on C. pilosula tissues. Changes in the main active ingredients of C. pilosula after ozone treatment were analyzed, and the effects of ozone treatment on the integrity of cell membranes in C. pilosula tissue and reactive oxygen species (ROS) metabolism were studied. The results showed that ozone treatment had a significant inhibitory effect on the A. elegans-induced mucor rot in C. pilosula, significantly reducing the incidence of the disease. Compared with the control group, the ozone-treated group maintained the effective components of C. pilosula well. Furthermore, ozone treatment reduced the cell membrane permeability and Malondialdehyde (MDA) content in C. pilosula, significantly increased the activity of antioxidant enzymes in the ROS metabolism pathway, prevented oxidative stress caused by the accumulation of ROS in C. pilosula tissues, and maintained the integrity of cell membranes.