Abstract
Utilizing antagonistic yeasts is a promising approach for managing postharvest decay of fruits. However, it is well established that various severe stresses encountered in the environment and production process cause the intracellular reactive oxygen species (ROS) accumulation in yeast cells, resulting in cell damage and loss of vitality. Here, proline has been shown to function as a cell protectant and inducer of biofilm formation able to increase the oxidative stress tolerance and the biocontrol ability of the antagonistic yeast Metschnikowia citriensis. Addition of proline to M. citriensis cells induced a significant rise in superoxide dismutase (SOD) and catalase (CAT) activity in the early and late stages of oxidative stress, respectively, and increased the maroon pigment production that directly reduced intracellular iron content and indirectly diminished intracellular ROS levels and thus inhibited ROS- and iron-induced apoptosis. Treating cells with iron chelator tropolone yielded similar results. Pigment production induced by proline also enhanced the capability of biofilm formation of M. citriensis. These results suggested an important role for pigment of M. citriensis in response to oxidative stress. The abilities of proline to scavenge intracellular ROS and inhibit apoptosis, increase pigment production, and promote biofilm formation contribute to the improvements in oxidative stress tolerance and biocontrol efficacy of M. citriensis.
Highlights
Postharvest fruits decay caused by fungal pathogens results in a large amount of economic losses and possible occurrence of mycotoxin contamination (Mahunu et al, 2016; Zhang et al, 2018)
The mold stock culture was incubated at 25°C for 7 days on potato dextrose agar (PDA) medium [200 g/L potatoes, 20 g/L dextrose, 20 g/L agar (Aobox, China)], and spores suspension was obtained by flooding the spores of the 7-day culture with sterile distilled water (SDW) and filtering through four layers of sterile gauze
The oxidative stress imposed by 40 mM H2O2 for 90 min was semi-lethal to M. citriensis cells, and this oxidative stress condition was chosen for subsequent experiments (Figure 1)
Summary
Postharvest fruits decay caused by fungal pathogens results in a large amount of economic losses and possible occurrence of mycotoxin contamination (Mahunu et al, 2016; Zhang et al, 2018). A growing body of new antagonists has been isolated from environment, and many biocontrol products have been developed and are mostly available in the agricultural markets in North America and Europe (Borriss, 2015). Several of these antagonists have not achieved commercial success due to inconsistent results, and most of the biocontrol products have limited application on fruit crops (Droby et al, 2016). Biocontrol agent biofilms on the surface of the host tissue that prevent new growth of pathogens and avoid their invasion greatly improve the biocontrol efficacy of antagonistic yeasts against postharvest diseases (Liu et al, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
