Abstract Penicillium expansum is a major postharvest fungal pathogen and is the causal agent of blue mold decay in apples. Epsilon-poly- l -lysine (e-PL) is a naturally-occurring polypeptide that has strong antimicrobial activity. It is primarily used to suppress foodborne pathogens in bread, beverage, meat products, etc. The potential application of e-PL in the management of fungal postharvest diseases of fruit, however, has not been explored. In the present study, the inhibitory effect of e-PL against blue mold (P. expansum) disease of apples and its potential mechanism of action were investigated. Results indicated that 600 mg L−1 of e-PL could effectively inhibit mycelial growth of P. expansum in apples. Concentrations of e-PL > 200 mg L−1 also inhibited germination of conidia and germ tube growth of P. expansum in potato dextrose broth (PDB). The inhibitory effect increased with increasing concentrations of e-PL concentration. Further studies indicated that the possible mechanisms involved of e-PL inhibition of P. expansum included the activation of defense-related enzyme activity and gene expression in apple fruit tissues. This included polyphenol oxidase (PPO), catalase (CAT), peroxidase (POD) and phenylalanine ammonialyse (PAL). e-PL stimulated the production of intracellular reactive oxygen species (ROS) and degraded the integrity of the cell wall and plasma membrane of conidia, resulting in the death of conidial spores of P. expansum or their germination.

中文翻译：

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epsilon-poly-L-赖氨酸抑制苹果采后蓝霉病的功效及潜在机制

摘要 Penicillium expansum 是一种主要的收获后真菌病原体，是导致苹果蓝霉腐烂的病原体。Epsilon-poly-l-lysine (e-PL) 是一种天然存在的多肽，具有很强的抗菌活性。它主要用于抑制面包、饮料、肉制品等中的食源性病原体。然而，尚未探索 e-PL 在水果采后真菌病害管理中的潜在应用。在本研究中，研究了 e-PL 对苹果蓝霉菌 (P. expansum) 病害的抑制作用及其潜在的作用机制。结果表明，600 mg L-1 的e-PL 可有效抑制苹果中P. expansum 的菌丝生长。e-PL > 200 mg L−1 的浓度也抑制了分生孢子的萌发和 P. 的胚管生长。马铃薯葡萄糖肉汤 (PDB) 中的膨胀剂。抑制作用随着 e-PL 浓度的增加而增加。进一步的研究表明，e-PL 抑制 P. expansum 的可能机制包括激活苹果果实组织中防御相关酶活性和基因表达。这包括多酚氧化酶 (PPO)、过氧化氢酶 (CAT)、过氧化物酶 (POD) 和苯丙氨酸氨解酶 (PAL)。e-PL 刺激细胞内活性氧 (ROS) 的产生并降低分生孢子细胞壁和质膜的完整性，导致 P. expansum 分生孢子死亡或萌发。扩展包括激活苹果果实组织中与防御相关的酶活性和基因表达。这包括多酚氧化酶 (PPO)、过氧化氢酶 (CAT)、过氧化物酶 (POD) 和苯丙氨酸氨解酶 (PAL)。e-PL 刺激细胞内活性氧 (ROS) 的产生并降低分生孢子细胞壁和质膜的完整性，导致 P. expansum 分生孢子死亡或萌发。扩展包括激活苹果果实组织中与防御相关的酶活性和基因表达。这包括多酚氧化酶 (PPO)、过氧化氢酶 (CAT)、过氧化物酶 (POD) 和苯丙氨酸氨解酶 (PAL)。e-PL 刺激细胞内活性氧 (ROS) 的产生并降低分生孢子细胞壁和质膜的完整性，导致 P. expansum 分生孢子死亡或萌发。