The Species Diversityof Dark Septate Endophytes Of Ammopiptanthus Mongolicus

Ammopiptanthus mongolicus(Maxim. ex Kom.) S. H. Cheng is the only evergreen broad-leaf legume shrub found in the desert area of northwestern China, and it belong to national levels endangered plants. It is particularly suited for the revegetation of degraded lands, which can reduce desertification. Dark septate endophytes(DSE) were a group of small soil fungal, which colonized in plant root cells orintercellular space, and had similar ecological function of arbuscular mycorrhizal fungi.The main objectives of this work were to study the species diversity and spatial status of DSE in the rhizosphere of A. mongolicus in Wuhai, Urad Back Banner and Alxa Left Banner, located in Inner Mongolia, and assess the effects of soil factors on these DSE. They are discussed by the growth of some typical DSE characteristics and chemical composition content. The data will help elucidate the natural history of these fungi. The utilizing of DSE resources for managing desert ecosystems is also discussed, and provide the basis for the desert vegetation restoration. The main results as follows:1. Acid fuchsin staining microscopy confirmed the ubiquity of DSE hyphae and microsclerotia-like structures in root tissues, and have many typical structures. The colonization of DSE fungi varied regularly with the altitude from the low to high, i.e. hyphae became thick, hyphal color deepened gradually, and the diaphragm was more common and shorter. Microsclerotia showed diversity, and dispersed granular gradually gathered into clusters, and appear the labyrinth, color also show different laws of the change. The hyphae, microsclerotia and total colonization rate increased gradually.2. Sampling sites and soil depth had a significant influence on the morphology, distribution and infection of DSE. Hyphae, microsclerotia and total root infection of DSE reached their maxima in the 0-20 cm soil layer, and showed a decreasing trend with soil depth increasing. With the increase of altitude, hyphae, microsclerotia and total colonization rate must be changed regularly. These of high altitude at Alxa Left Banner site was significantly higher than that of Wuhai and Urad Back Banner sites. Principal component analysis indicated that soil organic matter, phosphatase and available N were the main soil factors at Inner Mongolia desert habitats, correlation analysis also showed that DSE infection was closely related to the three factors, and hyphae and microsclerotia weresignificant positive correlation, and urease, organic matter and acid phosphatase were extremely significantly positive correlation(P<0.01), and the available P was significantly positive correlation(P<0.05), soil p H, available P and acid phosphatase were significantly positive correlation(P<0.05).3. With the change of ecological conditions, such as altitude and precipitation number, five types of microorganisms showed the same variable trend, i.e. the quantity of bacteria > sporeforms > actinomyces > azotobacter > fungi in three sample sites. Between the sample sites, the quantity of bacteria, sporeforms, azotobacter and actinomycesin Wuhai was significantly higher than that of Urad Back Banner and Alxa Left Banner, the quantity of fungi at Urad Back Banner were significantly higher than those of Wuhai and Alxa Left Banner. Different soil layers, there was a significant difference in the five types of microorganisms, the vertical dynamic distribution obviously, that in the 0-20 cm soil layer was significantly higher than that of other soil layers, with the deepening of soil layer, the quantity decreased.Correlation analysis showed that bacteria, fungi and actinomyceswere associated with soil organic C, Alkaline hydrolysis N and alkaline phosphatase significantly positive correlation.4. 274 strains of DSE were isolated in three sampling sites. 12 kinds weredivided by using morphological and molecular biology methods, and belonging to 9 genus.There are rare Leptodontidium orchidicola, Sarocladium kiliense and Alternaria alternata and more common Phialophora mustea, Paraphoma chrysanthemicola, Cladosporium sp., Phoma, Exophiala and Phialophora. Phialophora mustea is commongenus of Wuhai and Alxa Left Banner, and Paraphoma. sp is commongenus of Wuhai and Urad Back Banner, and Cladosporium is commongenus of Alxa Left Banner and Urad Back Banner. 10 species of DSE produced spores, accounted for more than 80%, is inconsistent with the view of many kinds of literature. The reason may be due to the ecological environment and the target plant specific difference further research.5. Fungal universal primers ITS4 and ITS5 r DNA were used to PCR amplification, the length of target gene fragment was between 525 bp and 627 bp. The results showed that sequence similarity of 12 kinds of DSE and closest strains was more than 97% through online BLAST sequence alignment.6. The main reason of Shannon-Wiener index lower DSE in three sites due to the low abundance of fungi, environmental heterogeneity in different sites increased DSE colonization group.Simpson index and Pielou index were similar, indicating that distribution of DSE type in three sites is more uniform.7. Three typical DSE strains were initially identified based on the optimum culture conditions of solid, i.e. using the PDA medium, and adding 0.4% peptone; 25 C, p H7, dark culture.By comparing the colony morphology and spore mycelial morphology before and after optimization, the optimization effect is good.8. Melanin content of WLTHQ-2 Cladosporium cladosporioidesin Urad Back Banneris significantly higher that of WH(4)10-20 Phialophora mustea in Wuhai and ALS(3)30-40 Alternaria alternatein Alxa Left Banner. Trace elements Mn, Zn and K content also appeared significant changes, and melanin content of DSE fungi are basically the same.