Temporal and spatial dynamics and functional metabolism of dark septate endophytes of Gymnocarpos przewalskii Maxim. in Northwest Desert, China

In extreme habitats, plants can survive mutually with their beneficial colony partners. How dark septate endophytes (DSE) assist the relict plant Gymnocarpos przewalskii survive in extremely desert environment and maintain the stability of the ecosystem remains unclear. Studying distribution, seasonal changes and functional physiological responses of DSE colonized in roots of G. przewalskii can help understand symbiosis mechanism of these endophytes associated to relict plants in extremely arid desert environments. DSE colonization, species diversity and soil properties of G. przewalskii were measured in Anxi and Minqin sites, Northwest China in July, September and December 2019. Subsequently, the functional metabolism of DSE strain was measured, and the response of DSE strain to drought stress was performed in vitro. DSE hyphal colonization (23.3 % - 39.2 %) and DSE isolation frequency (6.0 % - 27.6 %) varied sharply among seasons and sites. Soil alkaline phosphatase, nitrate nitrogen and total phosphorus were main factors affecting the DSE composition. Twenty-six DSE isolates produced indole-3-acetic acid (IAA) in the medium, while 50 % of DSE showed a potential for IAA production in L-tryptophan-dependent. Additionally, the composition of functional metabolites of DSE strains varied greatly with different drought levels and DSE isolates, which may indirectly reflect the complementarity between different strains in helping hosts cope with drought stress. This study confirmed the temporal and spatial dynamics and growth-promoting and drought-tolerant potential of DSE community in desert environment, and provided a new perspective for exploring the survival strategy and vegetation protection of desert relict plants.

Automated summary

In extreme desert environments, black septate endophytes (DSE) can benefit the relict plant Gymnocarpos przewalskii by assisting it to survive and maintain ecosystem stability. The colonization of DSE in the roots of G. przewalskii varies significantly with seasons and sites, with soil properties being a major factor affecting the composition of DSE. Additionally, the functional metabolite composition of DSE strains varies greatly with different drought levels and isolates, indicating the potential complementarity between different strains in helping hosts cope with drought stress.