Species diversity and drought tolerance of culturable dark septate endophytes in Anemone tomentosa in the Taihang mountain area.

Abstract

Frequent drought events pose escalating threats to global ecosystems, driving vegetation degradation, biodiversity loss, while destabilizing ecosystem functions. Dark septate endophytes (DSE), which exhibit drought stress tolerance in vitro and have the potential to enhance plant drought tolerance in arid environments, represent a key microbial component possibly mitigating drought impacts. Therefore, this study focuses on the dominant drought-tolerant plant Anemone tomentosa (A. tomentosa) and its symbiotic DSE in the drought-prone Taihang Mountain area, aiming to reveal the community composition, spatial distribution and functions of DSE, explore their application potential in arid environments, and provide a basis for fully utilizing DSE resources to promote vegetation restoration and ecological reconstruction in arid regions. Root and soil samples of A. tomentosa were collected from six sampling sites in the Taihang Mountain area to systematically investigate DSE colonization, community composition, species diversity and their correlations with soil environmental factors across different sites. Then six DSE strains with high isolation frequencies were selected for the drought resistance study in pure cultures, and varying polyethylene glycol (PEG-6000) concentrations (0%, 15%, 25%, And 35%) were set to simulate drought stress. The results showed that the roots of A. tomentosa at all six sampling sites in the Taihang Mountain area were highly colonized by DSE, forming typical dark-colored septate hyphae And microsclerotia structures. A total of 20 DSE strains belonging to 14 genera were isolated and identified, and the community composition of DSE at different sampling sites differed significantly (P < 0.05). The results of redundancy analysis (RDA) showed that soil organic carbon and soil total phosphorus were the Main factors influencing the community composition of DSE. The growth of 5 frequently isolated DSE strains under pure culture conditions was not adversely affected by drought stress, except for Exophiala xenobiotica (Ex), and biomass accumulation increased significantly with increasing drought stress, which was related to the content of antioxidant enzymes, osmotic adjustment substances, membrane lipid peroxidases and melanin in the different fungi. In summary, A. tomentosa in Taihang Mountain has rich DSE species diversity, and the two can form a symbiotic relationship, thus enhancing the adaptability of A. tomentosa to the environment. Five DSE strains exhibited drought stress tolerance under in vitro culture conditions, which enriched the understanding of the ecological functions and adaptive mechanisms of DSE in arid environments and provided a basis for the development and application of drought-resistant and water-preserving microbial agents.