Sodium pheophorbide a controls cherry tomato gray mold (Botrytis cinerea) by destroying fungal cell structure and enhancing disease resistance-related enzyme activities in fruit

Abstract

Sodium pheophorbide a (SPA) is a natural photosensitizer. The present study investigated the antifungal activity and mechanism of SPA against Botrytis cinerea in vitro and in vivo. Its inhibitory effect was studied on the spore germination and mycelial growth of B. cinerea. The effects of SPA on cell wall integrity, cell membrane permeability, and mycelial morphology of B. cinerea were also determined. Additionally, how SPA effected B. cinerea in vivo was evaluated using cherry tomato fruit. The results showed that SPA effectively inhibited the spore germination and mycelial growth of B. cinerea under light conditions (4000 lx). SPA significantly affected both cell wall integrity and cell membrane permeability (P < .05). In addition, SEM analysis suggested that B. cinerea treated with SPA (12.134 mg/mL) showed abnormal mycelial morphology, including atrophy, collapse, flattening, and mycelial wall dissolution. In vivo tests showed that SPA could increase the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) significantly (P < .05); however, SPA had no significant effect on phenylalanine ammonia lyase (PAL) activity. In short, SPA could destroy the fungal cell structure and enhance disease resistance-related enzyme activity in cherry tomatoes, thereby controlling cherry tomato gray mold.