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Fungal pathogen contamination is one of the most important factors affecting the postharvest quality and shelf life of wolfberry fruits. Therefore, the prevention and control of fungal pathogens that cause fruit rot has become particularly important. Volatile antifungal agents of biological origin have broad application prospects. They may be safer and more efficient than traditional physical and chemical methods. Four pathogenic fungi were isolated and purified from rotting wolfberry. These pathogenic fungi were determined to be Mucor circinelloides LB1, Fusarium arcuatisporum LB5, Alternaria iridiaustralis LB7, and Colletotrichum fioriniae LB8. In vitro fumigation experiments showed that 2,3-butanedione can effectively inhibit the mycelial growth, spore germination, and sporulation ability of pathogenic fungi. The scanning electron microscope (SEM) showed morphological changes in hyphae. Propidium iodide (PI) Staining and leakage of 260 and 280 nm-absorbing increased, suggesting damage to cell membranes. Furthermore, 2,3-butanedione was found to significantly improve fruit firmness, soluble solid, total phenol, flavonoid, and soluble sugar content, as well as higher SOD enzyme activity and lower PPO and POD enzyme activity in the treated fruit, indicating that 2,3-butanedione can effectively reduce the adverse effects of pathogenic fungi in wolfberry. Based on these results, we conclude that 2,3-butanedione is effective against infection by pathogenic fungi in post-harvest wolfberry. 2,3-butanedione should be considered a viable substitute for conventional fungicides that are currently used to control rot in wolfberry.

Volatile organic compounds (VOCs) produced by antagonistic microorganisms have good biocontrol prospects against postharvest diseases. Infection caused by Alternaria iridiaustralis and 10 other significant fungal diseases can be successfully inhibited by VOCs produced by an identified and screened endophytic strain L1 (Bacillus velezensis). This study revealed the in vivo and in vitro biocontrol effects of VOCs released by B. velezensis L1 on A. iridiaustralis, a pathogenic fungus responsible for rot of wolfberry fruit. The inhibition rates of VOCs of B. velezensis L1 on the mycelial growth of A. iridiaustralis in vitro were 92.86 and 90.30%, respectively, when the initial inoculum concentration on the plate was 1 × 109 colony forming unit (CFU)/ml. Spore germination and sporulation were 66.89 and 87.96%, respectively. VOCs considerably decreased the wolfberry’s disease index and decay incidence in vivo. Scanning electron microscopy revealed that the morphological and structural characteristics of A. iridiaustralis could be altered by VOCs. Ten VOCs were identified through headspace-gas chromatography-ion mobility spectrometry. Pure chemical tests revealed that 2.3-butanedione had the strongest antifungal effects, totally inhibiting A. iridiaustralis in wolfberry fruit at a 60 μl/L concentration. The theory underpinning the potential application of VOCs from B. velezensis is provided herein. This is also the first study to document the antifungal capabilities of the B. velezensis strain on postharvest wolfberry fruit.GRAPHICAL ABSTRACT