The Colonization And Species Diversity Of Dark Septate Endophytes Of Ammopiptanthus Mongolicus

Ammopiptanthus mongolicus was not only a super xerophytic evergreen leguminous shrub grown in northwestern sandland, China, but also an ancient third century relic species. It not only had medicinal value, such as activating blood and expelling wind, and relieving pain etc, but also had ecological value, such as windbreak and sand fixation, and landscape greening etc. Dark septate endophytes(DSE) were a group of small soil fungal, which colonized in plant root cells or intercellular space and had similar ecological function of arbuscular mycorrhizal fungi.In this research, Yinchuan, Shapotou and Minqin were selected, the interaction was studied between plants and soil fungi as an entry point, we systemically studied on ecological distribution and species diversity of DSE fungi in roots of A.mongolicus and the effects of the soil factors. DSE fungi resources were utilized to promote A.mongolicus plants growth and provide the basis for the desert vegetation restoration.The main results as follows:1. This study indicated that A.mongolicus can be highly infected by DSE, which formed typical dark septate hyphae and "microsclerotia". The main distribution type of microsclerotia are discrete and polymerization. The colonization and distribution of DSE had obvious spatial heterogeneity.2. DSE total colonization rate had extremely significantly positive correlation with soil temperature, which had extremely significantly negative correlation with p H and organic matter, and had significantly negative correlation with the acid phosphatase; alkali N was positively correlated with the ratio of microsclerotia/root length; available P was extremely significantly positively correlated with the ratio of microsclerotia/root length, and was significantly negatively correlated with the ratio of microsclerotia/root area; spatial variation of soil enzyme activity and DSE colonization were the same.3. 166 strains of DSE were isolated in three sampling sites, 10 kinds were divided by morphological identification, 5 kinds could sporulate and the other kinds could not sporulate. There were 4 kinds in Shapotou, 3ASPT1218 strain wasdominant species; there were 4 kinds in Minqin, 0-10MQ1217-2-2 strain was dominant species; there were 2 kinds in Yinchuan, which were 8YC and 4YC0-10 strain.4. Fungal universal primers ITS4 and ITS5 r DNA were used to PCR amplification, 10 DSE strains were measured after purification and recovery, the length of target gene fragment was between 525 bp and 617 bp. The results showed that sequence similarity of DSE and closest strains was between 97% and 99%through online BLAST sequence alignment, 10 kinds of DSE were belonged to 6genus, which were Cladosporium sp., Exophiala sp., Phialophora sp., Paraphoma sp.,Phoma sp., Pleosporales sp., respectively.5. The isolation rate of DSE had significant differences in different sampling sites. The highest value was 27% in Minqin, the lowest value was 5.67% in Yinchuan.The diversity index had significant differences among Yinchuan and Shapotou and Minqin, such as species richness, Shannon-Wiener index, Simpson index and Pielou index.6. The similarity coefficients(Jaccard index and Sorenson index) of DSE from different sampling sites were less than 0.33, which were lowest between Shapotou and Minqin, Jaccard index was 0.143, Sorenson index was 0.25. The results showed that distribution of DSE in roots of A.mongolicus had obvious spatial heterogeneity.