Screening for native <i>Trichoderma</i> strains as potential biocontrollers of the olive pathogen <i>Verticillium dahliae</i>

<i>Verticillium dahliae</i> is a soilborne pathogen that causes significant losses in olive crops in northwestern Argentina. Biological control through antagonistic microorganisms such as <i>Trichoderma</i> has great potential in the management of <i>Verticillium</i> wilt of olive. This investigation aims to isolate, identify and characterize native <i>Trichoderma</i> strains for biocontrol of <i>V. dahliae</i>. Thirty-nine <i>Trichoderma</i> strains were isolated from soils of olive orchards and natural areas and they were morphologically and molecularly characterized. Desired attributes for plant growth and bioprotection, such as indole acetic acid (IAA) production, endophytism and antagonistic potential against the pathogen were evaluated. Thirteen <i>Trichoderma</i> species were identified, belonging to the <i>Trichoderma, Longibrachiatum, Virens,</i> and <i>Harzianum</i> clades. Physiological characterization revealed that fourteen strains produced IAA while ten showed endophytic capacity. The antagonistic parameters quantified were very variable: eight strains showed high growth inhibition values (PI &gt; 65%), while six strains reached mycoparasitism (PM) values higher than 90% for both pathogens. Three endophytic strains exhibited IAA production and antagonistic activity against <i>V. dahliae</i>, becoming potential candidates for bioprotection of olive orchards. Olive cultivation in the arid regions of northwestern Argentina is subjected to strong stress conditions mainly due to the type of soils with low organic matter content and water retention. Thus, selected <i>Trichoderma</i> strains with more than one beneficial attribute are a fundamental tool for sustainable olive cultivation, not only as antagonists of emerging pathogens but also as mitigators of abiotic stress conditions that prevail in these environments.大丽轮枝菌（Verticillium dahliae）是一种土传病原菌，可造成阿根廷西北部橄榄作物的严重减产。通过木霉属（Trichoderma）等拮抗性微生物开展生物防治，在橄榄黄萎病的防控中具备巨大应用潜力。本研究旨在分离、鉴定并表征用于防治大丽轮枝菌的本土木霉菌株。研究人员从橄榄园与自然区域的土壤中分离得到39株木霉菌株，并对其进行了形态学与分子生物学表征。随后评估了其在植物生长促进与生物防护方面的目标特性，包括吲哚乙酸（indole acetic acid, IAA）合成能力、内生定殖能力以及对该病原菌的拮抗活性。共鉴定出13个木霉物种，隶属于木霉（Trichoderma）、长枝木霉（Longibrachiatum）、绿木霉（Virens）以及哈茨木霉（Harzianum）演化支。生理特性表征结果显示，14株菌株可合成IAA，10株菌株具备内生定殖能力。定量得到的拮抗参数差异显著：8株菌株对病原菌的生长抑制率（PI）高于65%，另有6株菌株对两种病原菌的重寄生作用值（PM）均超过90%。其中3株内生菌株兼具IAA合成能力与抗大丽轮枝菌活性，可作为橄榄园生物防护的潜在候选菌株。阿根廷西北部干旱地区的橄榄种植面临强烈环境胁迫，这主要源于其土壤有机质含量低、保水能力差的特性。因此，筛选获得具备多种有益特性的木霉菌株，是实现可持续橄榄种植的核心工具：此类菌株不仅可作为新发病原菌的生物拮抗剂，还能缓解该类环境中普遍存在的非生物胁迫。