Strawberry tree (Arbutus unedo, Ericaceae) is an evergreen tree with a circum-Mediterranean distribution. It has a great ecological and economic importance as a source of bioactive compounds with industrial applications and for fruit production. This study aims to characterize the fungi microbiome of this forestry species in order to develop biological control strategies in the increasing orchard production area. For this purpose, fungi endophytes were isolated from wild strawberry tree plants, and a molecular identification was carried out. In vitro assays were carried out to evaluate and characterize the antagonism of some endophytes. Among the several fungi endophytes isolated from strawberry tree (a total of 53 from 20 genera), a Trichoderma atroviride strain proved to have antagonism effect against several phytopathogens, including Alternaria alternata, Botrytis cinerea, Glomerella cingulata, and Mycosphaerella aurantia. This antagonism was particularly effective against Phytophthora cinnamomi, causing a reduction in growth of about 80% on this invasive oomycete. An enzymatic assay revealed the production of several enzymes by T. atroviride, such as cellulases, chitinases, glucosidases, alkaline phosphatases, and proteases, which is one of the several mechanisms known to be involved on Trichoderma biological control ability. The enzymatic activity, in particular that of cell wall–degrading enzymes, was accentuated when in a dual culture with P. cinnamomi. The production of serine proteases, aspartyl proteases, metalloproteases, and cysteine proteases was also detected in an experiment carried out in liquid medium, suggesting the involvement of these proteases on Trichoderma mycoparasitism mechanisms. Finally, in a three-way interaction with in vitro strawberry tree plants, the T. atroviride strain identified on this study (Au50) was able to protect the plants against P. cinnamomi, thus proving its potential as a biological control agent.

草莓树（Arbutus unedo，Ericaceae）是一种常绿乔木，分布于环地中海。作为具有工业应用和水果生产的生物活性化合物的来源，它具有重要的生态和经济重要性。本研究旨在表征这种林业物种的真菌微生物组，以便在不断增加的果园生产区制定生物控制策略。为此，从野生草莓树植物中分离出真菌内生菌，并进行了分子鉴定。进行体外测定以评估和表征某些内生菌的拮抗作用。在从草莓树中分离出的几种真菌内生菌（共 20 属 53 种）中，一种木霉菌株被证明对多种植物病原体具有拮抗作用，包括交替链格孢、灰葡萄孢、Glomerella cingulata和Mycosphaerella aurantia。这种拮抗作用对肉桂疫霉特别有效，导致这种侵入性卵菌的生长减少约 80%。酶促测定揭示了T. atroviride产生了几种酶，例如纤维素酶、几丁质酶、葡糖苷酶、碱性磷酸酶和蛋白酶，这是已知与木霉有关的几种机制之一生物防治能力。当与P. cinnamomi进行双重培养时，酶活性，特别是细胞壁降解酶的活性更加突出。在液体培养基中进行的实验中也检测到丝氨酸蛋白酶、天冬氨酰蛋白酶、金属蛋白酶和半胱氨酸蛋白酶的产生，表明这些蛋白酶参与了木霉菌寄生机制。最后，在与体外草莓树植物的三向相互作用中，本研究中鉴定的T. atroviride菌株 (Au50) 能够保护植物免受P. cinnamomi的侵害，从而证明其作为生物防治剂的潜力。