Microbial secondary metabolites produced by Streptomyces are applied to control plant diseases. ε-poly-l-lysine (ε-PL) is a non-toxic food preservative, but the potential application of ε-PL as a microbial fungicide in agriculture has rarely been reported. In this study, Alternaria alternata (A. alternata) was used to reveal the effect and mode of action for ε-PL on the plant pathogenic fungi. The results showed that ε-PL effectively inhibited necrotic-lesion development caused by A. alternata on tobacco. Mycelial growth was also significantly inhibited in vitro by 100 μg/ml ε-PL using in vitro analysis. Moreover, 25 μg/ml ε-PL inhibited spore germination and induced abnormal morphological development of A. alternata hyphae. To clarify the molecular-genetic antifungal mechanisms, we selected several crucial genes involved in the development and pathogenesis of A. alternata and studied their expression regulated by ε-PL. Results of real-time quantitative PCR showed that a mycelium morphology and pathogenic process related cyclic adenosine monophosphate protein (cAMP) dependent protein kinase A (PKA), Alternaria alternata cAMP-dependent protein kinase catalytic subunit (AAPK1) and the early infection-related glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were down-regulated after ε-PL treatment. The results provide novel insights for the application of ε-PL in the control of plant diseases caused by A. alternata.

中文翻译：

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ε-聚-L-赖氨酸对感染烟草的链格孢营养生长、致病性及基因表达的影响

链霉菌产生的微生物次级代谢产物用于防治植物病害。ε-poly-l-lysine (ε-PL) 是一种无毒的食品防腐剂，但 ε-PL 作为微生物杀菌剂在农业中的潜在应用鲜有报道。在这项研究中，Alternaria alternata (A. alternata) 被用来揭示 ε-PL 对植物病原真菌的影响和作用方式。结果表明，ε-PL有效抑制了A.alternata引起的烟草坏死病灶的发展。使用体外分析，100 μg/ml ε-PL 在体外也显着抑制了菌丝体生长。此外，25 μg/ml ε-PL 抑制孢子萌发并诱导 A. alternata 菌丝的异常形态发育。为了阐明分子遗传抗真菌机制，我们选择了几个参与 A. alternata 发育和发病机制的关键基因，并研究了它们受 ε-PL 调控的表达。实时定量 PCR 结果表明，菌丝体形态和致病过程相关的环磷酸腺苷蛋白 (cAMP) 依赖性蛋白激酶 A (PKA)、链格孢 cAMP 依赖性蛋白激酶催化亚基 (AAPK1) 和早期感染相关的甘油醛-3-磷酸脱氢酶 (GAPDH) 在 ε-PL 处理后下调。该结果为 ε-PL 在控制由互生孢子菌引起的植物病害中的应用提供了新的见解。实时定量PCR结果表明，菌丝体形态和致病过程相关的环磷酸腺苷蛋白（cAMP）依赖性蛋白激酶A（PKA）、链格孢cAMP依赖性蛋白激酶催化亚基（AAPK1）和早期感染相关的甘油醛-3-磷酸脱氢酶 (GAPDH) 在 ε-PL 处理后下调。该结果为 ε-PL 在控制由互生孢子菌引起的植物病害中的应用提供了新的见解。实时定量 PCR 结果表明，菌丝体形态和致病过程相关的环磷酸腺苷蛋白 (cAMP) 依赖性蛋白激酶 A (PKA)、链格孢 cAMP 依赖性蛋白激酶催化亚基 (AAPK1) 和早期感染相关的甘油醛-3-磷酸脱氢酶 (GAPDH) 在 ε-PL 处理后下调。该结果为 ε-PL 在控制由互生孢子菌引起的植物病害中的应用提供了新的见解。