Cannabinoids: A new natural agent to control postharvest decay development

Pathogenic fungi are a major cause of postharvest loss of fresh produce. While chemical fungicides effectively control postharvest diseases their use raises concerns and alternatives are required. Natural compounds with antifungal properties and natural defense response elicitors are explored. Among those compounds, phytocannabinoids are secondary metabolites generated from Cannabis sativa that are of particular interest. Among the non-psychotropic cannabinoids are cannabidiol (CBD) and cannabigerol (CBG). The current study investigates the effect of CBD and CBG’s effect on postharvest fungal pathogens and the fruit defense response. CBD and CBG inhibit the growth of major postharvest pathogens such as Botrytis cinerea, Penicillium expansum, and Colletotrichum gloeosporioides. Moreover, CBD and CBG significantly decreased gray mold development caused by B. cinerea on grapes. Studying their mode of action indicated that both CBD and CBG affected B. cinerea fungal cell wall composition and cell-wall-related remodeling genes, as well as cell membrane fluidity and permeability. CBD treatment causes hyperpolarization of the fungal mitochondria membrane, which results in increased intracellular ROS levels. Evaluation of the effect of CBD and CBG on the fruit defense response displayed a priming effect by up-regulating pathogenic related proteins and induced salicylic acid and flavonols production resulting in inhibition of decay development. Overall, the results of the current study reveal the direct and indirect ability of natural phytocannabinoids to control fungal decay development and reduce food loss. This novel eco-friendly postharvest treatment has the potential to replace chemically hazardous fungicides.