Abstract：Penicillium expansum is a major postharvest pathogen and quite harmful to fruit and vegetable preservation. Therefore, it is necessary to search for an effective control method. In this study, we isolated a P. expansum from naturally infected apples(Malus domestica) and identified it by rDNA-ITS method. The relationship between exogenous nitrc oxide(NO) with different concentrations and growth or pathogenicity of P. expansum were evaluated via assessment of germination ratio, germ tube length, mycelium extension speed, and inoculation experiment of apple. In addition, by determining level of reactive oxygen species, carbonylated proteins, and evaluating the content of malondialdehyde (MDA) and ATP, the possible inhibitory mechanism of exogenous NO on P. expansum was explored preliminarily. The results indicated that exogenous NO could inhibit the growth of P. expansum and the behavior was dose-dependent. It was speculated that the inhibitory effect came from accumulation of reactive oxygen species, which led to oxidative damages. This study provides a new approach to control postharvest horticulture pathogens potentially of fruit and vegetable
