Screening for native Trichoderma strains as potential biocontrollers of the olive pathogen Verticillium dahliae

Verticillium dahliae is a soilborne pathogen that causes significant losses in olive crops in northwestern Argentina. Biological control through antagonistic microorganisms such as Trichoderma has great potential in the management of Verticillium wilt of olive. This investigation aims to isolate, identify and characterize native Trichoderma strains for biocontrol of V. dahliae. Thirty-nine Trichoderma 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 Trichoderma species were identified, belonging to the Trichoderma, Longibrachiatum, Virens, and Harzianum 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 > 65%), while six strains reached mycoparasitism (PM) values higher than 90% for both pathogens. Three endophytic strains exhibited IAA production and antagonistic activity against V. dahliae, 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 Trichoderma 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，可导致阿根廷西北部橄榄作物遭受严重产量损失。利用木霉属（Trichoderma）拮抗微生物开展生物防治，在橄榄黄萎病的治理中具备极大应用潜力。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，并对其进行形态学与分子生物学表征。随后评估了其具备促植物生长与生物防护潜力的相关特性，包括吲哚乙酸（indole acetic acid, IAA）合成能力、内生性以及对该病原菌的拮抗潜能。 共鉴定出13个木霉物种，分属于木霉、长枝木霉（Longibrachiatum）、绿木霉（Virens）以及哈茨木霉（Harzianum）四个支系。生理特性表征结果显示，14株菌株可合成吲哚乙酸，10株菌株具备内生能力。所量化的拮抗参数差异显著：8株菌株表现出较高的生长抑制率（平板对峙抑制率PI > 65%），另有6株对两种供试病原菌的重寄生作用（mycoparasitism, PM）值均高于90%。其中3株菌株兼具吲哚乙酸合成能力、内生性以及对大丽轮枝菌的拮抗活性，成为橄榄园生物防护的潜在候选菌株。 阿根廷西北部干旱区域的橄榄种植面临较强的逆境胁迫，主要源于当地土壤有机质含量低、保水性差的特性。因此，筛选获得具备多重有益特性的木霉菌株，是实现橄榄可持续种植的核心工具——这类菌株不仅可作为新兴病原菌的拮抗菌，还能缓解当地环境中普遍存在的非生物逆境胁迫。