Colonization Strategy of Endophytic Fungi in the Typical Desert Plants Populus Euphratica and Haloxylon Ammodendron under Natural Drought Conditions

Arbuscular mycorrhizal fungi (AMF) and Dark septate endophytic (DSE) fungi are the most abundant and widespread endophytic fungi in the rhizosphere of plants that constitutes natural ecosystems. However, the interaction between AMF and DSE fungi under natural drought conditions and its influencing factors are still unclear. In this work we explore the seasonal dynamics of the colonization strategies of endophytic fungi in typical desert plants under natural drought conditions and their adaptability to drought. In this work, Populus euphratica and Haloxylon ammodendron, constructive species in the Ebinur Lake Wetland National Nature Reserve in Xinjiang, China, arewere used to study the colonization of AMF and DSE fungi in plant roots under different natural drought conditions, using electron microscopy and high-throughput sequencing. The results showed that (1) the AMF colonization rate is significantly different under seasonal variation and different drought gradients. There is a significant negative correlation with drought gradients (R = -0.83, P = 0.021) and a significant positive correlation between the colonization rates of AMF and DSE fungi (R = 0.38, P < 0.05). (2) The community compositions of AMF and DSE fungi change with the seasons and different drought gradients. With a change of drought gradient in spring and summer, the dominant genera of AMF change from Kamienskia and Rhizophagus to some unclassified fungi. Aporospora, Comoclathris, and Lophotrichus replace the dominant communities of Mortierella, Fusarium, and Podospora when the DSE community changes from spring to summer. (3) Soil moisture content, salt content, pH, and ammonium nitrogen significantly affect the colonization of AMF, while salt content, pH, available phosphorus, and total phosphorus significantly affect the colonization of DSE fungi. There is a significant relationship between AMF community and pH in spring, and there is a significant relationship between DSE fungi community and total nitrogen in spring and summer. This study reveals the colonization rules and driving factors of AMF and DSE fungi in natural arid habitats, providing a basis for proving that AMF and DSE fungi could promote the growth of Populus euphratica and Haloxylon ammodendron and further contribute to desertification control and vegetation restoration