Diversity And Chemical Components Of Dark Septate Endophyte (DSE) From Roots Of Ammopiptanthus Mongolicus (Maxim.) Cheng F. And Associated Plants

Dark septate endophytes(DSE) are a plant endophytic fungi that colonize living plant roots without causing apparent negative effects. The most important characteristic of DSE is the accumulation of melanin in hyphal walls, which developing melanized septate hyphae and microsclerotia. The wide distribution of DSE and the positive function in the stress environment, which has important ecological application value in the aspects of vegetation restoration and ecological reconstruction. Ammopiptanthus mongolicus and its association plants are growing with daily life, and together with evoluting during the long period of growing and evolution. A. mongolicus and its association plants in Gansu and Ningxia were objects to study structural characteristics of DSE, species diversity, community structure and the changes of chemical components. The research provided basis and references for further making use of DSE to promote soil conservation and ecological reconstruction. The results were as follows:1. The roots of A. mongolicus and its associated plants were infected by DSE which could be characterized by typical septate hyphae and microsclerotia. The average total colonization was 57.01% and 36.04%, respectively. In the same sites, the colonization of DSE of A. mongolicus had no evident trend different in soil layers, but the highest colonization of DSE of associated plants mostly appeared at the 0-20 cm soil depth. In different sites of 2013, the total colonization of DSE in A. mongolicus exhibited a pattern as Shapotou >Yinchuan>Minqin, and these indexes in associated plants were Yinchuan> Minqin> Shapotou. The total colonization of A. mongolicus and its associated plants had same variation in 2013 and 2015. In the same site, microsclerotia colonization in A. mongolicus and its associated plants showed no significant difference, but hyphal colonization, colonization intensity and total colonization of A. mongolicus were much higher than that of its associated plants.2. Plant species and soil layer had significant effects on the colonization and distribution of DSE as well as soil properties. The correlation analysis indicated that hyphal colonization, colonization intensity and total colonization were positive correction with available P and available N as well as the total colonization were positive correction with phosphatase. The principal component analysis indicated that soil organic matter, available P, available N and phosphatase were the main influencing factors, which directly affected the colonization of DSE in desert environment, northwest China.3. The DSE separated from the associated plants of A. mongolicus were 54 strains in 2013, divided into 6 genera 6 species and mostly were sterile under natural conditions. The DSE separated from A. mongolicus were 54 strains in 2015, divided into 4 genera 6 species among which 3 species spored. The DSE separated from the associated plants of A. mongolicus were 26 strains in 2015, divided into 4 species among which only one spored. In the natural state, the species numbers and types of spore of A. mongolicus were much more than its association plants.4. Pleospora was the common genera in A. mongolicus and its association plants at Minqin in 2013. Pleospora sp. was the common species in A. mongolicus and its association plants at Minqin and Shapotou in 2015. Alternaria sp., Embellisia sp., Phialocephala sp. and Curvularia sp. only existed in the association plants. Paraphoma sp., Exophiala sp., Cladosporium sp., and Phialophora sp. only existed in A. mongolicus. Pleospora sp.and Phoma sp. were both existed in A. mongolicus and its association plants. Some of them were first reported in the association plants of A. mongolicus, for example, Alternaria japonica, Embellisia sp., Curvularia eragrostidis.5. Outside of total protein content and mycelial biomass, other chemical components contents of 26 strains DSE were significantly different and the variation was not obvious. The most species with higher chemical components contents were dominant species in the sample plots, especially, the species with highest melanin content were all dominant species in the sample plots. In the aspect of nutrition metabolism, the utilization rate of P was closely related to sample environment and plant microenvironment.6. The first highest total chemical components content was Pleospora sp.(MQ-S-3), the second was P. chrysanthemicola(0-10MQ1217-2-2)and the lowest was Phoma sp.(4YC). The highest content of Mg was P. chrysanthemicola(0-10MQ1217-2-2), the highest content of Fe was Exophiala sp.(3ASPT1218), the highest content of Mn was Pleospora sp.(MQ-S-3), the highest content of Cu was Embellisia sp.(YC-2-1)and the highest content of Zn was C. cladosporioides(2SPT1218).Some of them are dominant species in corresponding year and sites, for example, MQ-S-3, 0-10MQ1217-2-2, 3ASPT1218, YC-2-1.