Postharvest decay of fruits, vegetables, and grains by fungal pathogens causes significant economic losses. Infected produce presents a potential health risk since some decay fungi produce mycotoxins that are hazardous to human health. Infections are the result of the interplay between host resistance and pathogen virulence. Both of these processes, however, are significantly impacted by environmental factors, such as temperature, UV, oxidative stress, and water activity. In the present review, the impact of various physical postharvest treatments (e.g., heat and UV) on the viability and virulence of postharvest pathogens is reviewed and discussed. Oxidative injury, protein impairment, and cell wall degradation have all been proposed as the mechanisms by which these abiotic stresses reduce fungal viability and pathogenicity. The response of decay fungi to pH and the ability of pathogens to modulate the pH of the host environment also affect pathogenicity. The effects of the manipulation of the postharvest environment by ethylene, natural edible coatings, and controlled atmosphere storage on fungal viability are also discussed. Lastly, avenues of future research are proposed.
As an eco-friendly management method, biological control of postharvest diseases, utilizing antagonistic yeasts, is a research topic receiving considerable attention. Detailed knowledge on the biology of yeast antagonists is crucial when considering their potential application and development as biocontrol products. Changes in the growth form, such as single-cell to pseudohyphae, have been associated with the mode of action in postharvest biocontrol yeasts. In this study, the antagonistic yeast, Candida diversa, reversibly shifted from a single-cell morphology on yeast peptone dextrose (YPD) medium with 2 % agar to a pseudohyphal morphology on YPD with 0.3 % agar. The tolerance of the pseudohyphal form to heat and oxidative stresses, as well as the biocontrol efficacy against Botrytis cinerea on apple and kiwifruit stored at 25 and 4 °C, was significantly higher as compared to the single-cell form. This study provides new information on the ability of C. diversa to change its morphology and the impact of the morphology shift on stress tolerance and biocontrol performance.
Ginger is a perennial monocotyledonous herb, which can be used as both a vegetable and a medicinal plant. However, it is susceptible to various plant pathogens. Microbial diversity in soil is related closely to the health and productivity of plant crops including ginger. In the current study, we compared microbial diversity from soil samples under ginger cultivation (disease incidence of >50% [relatively unhealthy sample] versus disease incidence of <10% [relatively healthy sample]). The bacterial and fungal taxa were analyzed by Illumina-based sequencing, with 16S and ITS identification, respectively. Both bacterial and fungal OTUs were significantly more in the healthy soil sample than the unhealthy sample. Moreover, the dominant bacterial and fungal genera were detected to be different in each sample. Rhodanobacter and Kaistobacter were the dominant bacterial genera in the healthy sample, while Rhodoplanes and Bradyrhizobium were the dominant genera in the unhealthy sample. For fungal analysis, Cladosporium, Cryptococcus, and Tetracladium were the dominant genera in the healthy sample, while Lecanicillium, Pochonia, and Rhodotorula were the dominant genera in the unhealthy sample. Collectively, the basic information of microbial diversity in ginger soil is helpful for elucidating the ginger-microbe interactions and potentially selecting suitable plant growth-promoting rhizobacteria and biocontrol agents for ginger production.
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