Diversity of arbuscular mycorrhizal fungi in the rhizosphere of Populus euphratica seedlings in Ebinur Lake Basin, Xinjiang

Objective: In this paper, the diversity of arbuscular mycorrhizal fungi in the rhizosphere of Populus euphratica seeding in the Xinjiang Ebinur Lake National Nature Wetland Reserve was investigated by spore identification and molecular phylogeny, in order to explore AM fungi ecology function and the regulatory mechanisms to plant community structure in desert ecosystem. Method: This study was conducted in the Xinjiang Ebinur Lake National Wetland Reserve, and the rhizosphere soil and root tissues of 7 P. euphratica seedlings were collected, respectively. The physical and chemical properties of the soil samples were determined, and the data were analyzed using SAS software. The wet sieving method was used to isolate the AM fungi spores from the rhizosphere soil of 7 P. euphratica seedlings and the spore pellet method was applied to identify the AM fungi species. Spore density and relative abundance were calculated, and AM fungi common structure and infection rate were observed. Meanwhile, the nested polymerase chain reaction was used to amplify rRNA gene fragments of AM fungi association with P. euphratica. Through sequence analysis and homology analysis, the rRNA gene fragments from AM fungi were identified and the reference sequences were obtained. Following, a phylogenetic tree was constructed with the new rRNA gene fragments and reference sequences by Mage software. Result: The results showed that, Na+, Mg2+ and Ca2+ concentrations in the rhizosphere soils were significantly lower than in background soils, while the organic matter content of the rhizosphere soils was higher than that of the background, and the K+ concentration distributed evenly. In the rhizosphere soil samples, nitrogen, phosphorus and sulfur contents were highly positively correlated with the organic matter content, while the contents of K+, Ca2+ and Na+ were highly negatively correlated with the organic matter content. Eight species belonging to 3 AM fungal genera were isolated and identified in the rhizosphere soil of 7 P. euphratica. In these species, G. dominikii, G. viscosum, G. reticulatum, G. melanosporum belonged to Glomus, A. morrowae, A. excavata, A.undulata to Acaulospora, and Scu. erythropa to Scutellospora. In addition, 13 new AM fungal taxa association with P. euphratica were identified and the Genbank accession number are KJ209699-KJ209711. After the analysis of Blast homologous alignment and phylogenetic relationship, the AM fungal taxa in P. euphratica were divided into two groups with less than 93% similarity, and the taxon of two AM fungal groups belong to different species of the genus Rhizophagus. Conclusion: The P. euphratica with AM fungi can significantly reduce salt concentrations in the rhizosphere soil, and simultaneously increase the organic matter content, as well as the contents of nitrogen, phosphorus and sulfur. In this study, 13 new AM fungal taxa association with P. euphratica were separated into two groups belonging to one genus. From this result, in the flora with P. euphratica as the constructive species, the AM fungi associated with constructive species have the host selectivity to avoid nutrition competition to each other, and hence regulate the structure of the plant community in flora. © 2016, Editorial Department of Scientia Silvae Sinicae. All right reserved.