Abstract

Purpose: This study aimed to isolate and assign at genus level the dark septate endophytes (DSE) that colonize native Ericaceae plants in the Andes Mountains of southern Chile and evaluate their plant growth-promotion traits and their in vitro tolerance to abiotic stress. Methods: We isolated, identified, and evaluated the characteristics of five DSE, Pezizomycotina sp, Alternaria sp.1, Phialocephala sp., Alternaria sp.2, Cladosporium sp. The DSE’s plant growth-promoting capabilities were assessed, encompassing their capacity to produce indoleacetic acid (IAA), phosphate solubilization, ammonia and siderophores. Additionally, their potential to enhance stress tolerance was evaluated through the production of exopolysaccharides (EPS) and ACC deaminase. Moreover, the DSE’s ability to tolerate aluminum and water stress was evaluated. Results: Alternaria sp.1, Alternaria sp.2 and Cladosporium sp. produce higher concentrations of IAA and ammonium (4.59 mg L-1 and 17.66 µmol mL-1; 9.87 mg L-1 and 24.37 µmol mL-1; 4.11 mg L-1 and 36.28 µmol mL-1, respectively), while Cladosporium sp. was able to solubilize phosphate from iron, aluminum and phytic acid sources. Cladosporium sp. produces the highest concentration of EPS (245 mg L-1). Phialocephala sp. tolerated the highest aluminum concentration (500 mg L-1) and water stress induced by PEG-6000, along with Cladosporium sp. Conclusion: We found that the dark septate endophytic fungi isolated from native Andean Ericaceae plants colonizing volcanic deposits in southern Chile possess unique characteristics that enable them to tolerate aluminum and water stress, making them ideal plant growth promoters in stressful environments. They could potentially play a crucial role in adapting plants to challenging environments and contribute to sustainable agriculture practices in this region. © The Author(s) under exclusive licence to Sociedad Chilena de la Ciencia del Suelo 2024.