Molecular Dissection of Rose and Botrytis Cinerea Pathosystems Affected by Ethylene

Botrytis cinerea (B. cinerea) is a necrotrophic pathogen that causes significant growth and postharvest commercial losses in cut roses. Postharvest disease severity is affected by ethylene levels during transport and storage conditions. In this study, we identified the relationship between ethylene, fungal growth, and ethylene inhibitors during B. cinerea infection in cut ‘Pink Beauty’ roses. The results suggest that cut rose susceptibility to gray mold disease is associated with the developmental stage of flowers, especially the level of senescence, which is stimulated by ethylene biosynthesis in petals. The mRNA levels of ethylene biosynthesis genes in petals were related to the severity of gray mold; however, their expression levels decreased when the cut roses were completely macerated by B. cinerea. B. cinerea infections in cut flowers activated ethylene biosynthesis and signaling pathways, leading to the activation of RhERFs in the petals. Ethylene regulated the development of B. cinerea infections in the cut flowers directly by binding to the receptors or indirectly by promoting the ethylene response in the host tissues. The suppression of ethylene responses in petals and inhibition of the fungal histidine kinase receptor of B. cinerea by 1-methylcylopropene (1-MCP) made cut rose flowers resistant to such necrotrophic pathogens. We also established a working model for ethylene binding and plant and fungus actions in the rose-B. cinerea pathosystem. Understanding the relationship between ethylene and gray mold disease in cut roses and the interaction between ethylene inhibitors and B. cinerea will help improve postharvest treatments for reducing B. cinerea damage in cut flowers.