ABSTRACT Endophytic fungi are microorganisms that inhabit internal plant tissues without causing apparent damage. During the infection process, both endophytic and phytopathogenic fungi secrete proteins to resist or supplant the plant’s defense mechanisms. This study analyzed the predicted secretomes of six species of endophytic fungi and compared them with predicted secretomes of eight fungal species with different lifestyles: saprophytic, necrotrophic, hemibiotrophic, and biotrophic. The sizes of the predicted secretomes varied from 260 to 1640 proteins, and the predicted secretomes have a wide diversity of CAZymes, proteases, and conserved domains. Regarding the CAZymes in the secretomes of the analyzed fungi, the most abundant CAZyme families were glycosyl hydrolase and serine proteases. Several predicted proteins have characteristics similar to those found in small, secreted proteins with effector characteristics (SSPEC). The most abundant conserved domains, besides those found in the SSPEC, have oxidation activities, indicating that these proteins can protect the fungus against oxidative stress, against domains with protease activity, which may be involved in the mechanisms of nutrition, or against lytic enzymes secreted by the host plant. This study demonstrates that secretomes of endophytic and nonendophytic fungi share an arsenal of proteins important in the process of infection and colonization of host plants.

中文翻译：

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内生和非内生真菌分泌组的预测揭示了宿主植物感染和定植策略的相似性

摘要 内生真菌是寄居在植物内部组织而不造成明显损害的微生物。在感染过程中，内生真菌和植物病原真菌都会分泌蛋白质来抵抗或取代植物的防御机制。本研究分析了 6 种内生真菌的预测分泌组，并将它们与具有不同生活方式的 8 种真菌物种的预测分泌组进行了比较：腐生、坏死、半生物营养和生物营养。预测的分泌组的大小从 260 到 1640 个蛋白质不等，并且预测的分泌组具有广泛多样的 CAZymes、蛋白酶和保守结构域。关于所分析真菌分泌组中的 CAZyme，最丰富的 CAZyme 家族是糖基水解酶和丝氨酸蛋白酶。几种预测的蛋白质具有类似于在具有效应特征的小分泌蛋白质 (SSPEC) 中发现的特征。除了 SSPEC 中发现的那些，最丰富的保守结构域具有氧化活性，表明这些蛋白质可以保护真菌免受氧化应激、具有蛋白酶活性的结构域（可能涉及营养机制）或分泌的裂解酶通过寄主植物。这项研究表明，内生和非内生真菌的分泌组共享在宿主植物感染和定殖过程中重要的蛋白质库。表明这些蛋白质可以保护真菌免受氧化应激、具有蛋白酶活性的结构域（可能与营养机制有关）或宿主植物分泌的裂解酶。这项研究表明，内生和非内生真菌的分泌组共享在宿主植物感染和定殖过程中重要的蛋白质库。表明这些蛋白质可以保护真菌免受氧化应激、具有蛋白酶活性的结构域（可能与营养机制有关）或宿主植物分泌的裂解酶。这项研究表明，内生和非内生真菌的分泌组共享在宿主植物感染和定殖过程中重要的蛋白质库。