Ecological Heterogeneity Of DSE Fungus In Anxi Extreme Arid Desert Environment In China

The roots and soil samples were collected from five typical desert vegetations,including Ephedra przewalskii,Reaumuria songarica,Sympegma regelii,Nitraria sphaerocarpa and Salsola passerina in the extremely arid desert nature reserve in Anxi,Gansu Province,July2016 and 2017.The objectives of this study were to study on ecological heterogeneity of DSE fungus by describing morphological characteristics of mycelium and microsclerotium of dark septate endophyte(DSE)and isolating strains from the roots of plant communities and soil samples,and to identify with morphological classification methods combined with molecular biology methods,at the same time,select some strains to culture under different conditions.In order to elucidate the characteristics of DSE fungal community composition and species diversity in extremely arid desert plants,It has great reference value to fully utilize DSE fungal resources and promote ecological restoration and vegetation restoration in ecologically fragile areas.The main results as follows:1.DSE colonization has spatiotemporal heterogeneity.DSE fungi can infect five desert plant communities and formed typical dark-colored septate mycelia and microsclerotia.The DSE colonization rates of on the roots of different plant species were significantly different,and the DSE colonization rate of the same plant was different among 2 years.E.przewalskii and S.passerina had higher DSE colonization and colonization intensity.2.Correlation analysis showed that plant species had significant direct effects on DSE colonization,while soil temperature,acid phosphatase,and urease had significant direct effects on DSE colonization.3.Using morphological and molecular biological methods,showed 13 species were isolated,namely,4 species of Alternaria sp.,2 species of Embellisia sp.,1 specie Curvularia sp.,1 specie of Paraphoma sp.,1 specie of Aporospora sp.,1 specie of Darksidea sp.,1specie of Tetracladium sp.,1 specie of Ulocladium sp.and 1 specie of Podospora sp.,including 7 spore-producing strains.Ulocladium chartarum and Embellisia astragali were dominant strains.4.The DSE fungi had a certain degree host preference.There was a significant difference in the species composition of the DSE strains.And the DSE species of R.songarica were the least,E.przewalskii and S.passerina were the most.5.DSE strains had different effects on low temperature,drought tolerance and salt tolerance.Different gradients of temperature,PEG concentration(simulated drought stress)and salt concentration were used to explore the growth conditions of DSE fungi under different culture conditions.It was founded that different culture conditions affect the growth of DSE strains.The colony and mycelium morphology of DSE strains were significantly different of the same DSE strains under different culture conditions and different DSE strains under the same culture conditions.