Abstract: In this study, arbuscular mycorrhizal fungi （AMF） of natural [WTBX]Populus euphratica[WTBZ] rhizosphere in the lower reaches of the Tarim River was investigated by using traditional morphological methods and molecular techniques. In particular, Nested-PCR was conducted to specifically amplify D1-D2 variable region nucleotide sequences of the smallsubunit （25S） rDNA from the AMF in the root and rhizospheric soil samples of Populus euphratica, respectively. The Nested-PCR products were applied to nucleotide sequence analysis and analyzed with phylogenetic analysis. The results indicate that the targeted product（786bp） was successfully amplified from trace DNA by Nested-PCR. Based on the Phylogenetic tree built with DNAMAN software, the nucleotide sequence analysis outcomes were appraised with Bootstraping method. According to the spore morphological properties and molecular analysis results, we know that under drought stress the dominant AMF species was Glomus mosseae in soil. The spore density of AMF within the rhizospheric soil of Populus euphratica was low. Glomus mosseae fungal spores were formed in the soil alone, inside of the roots or sporangium. The shape of the spore is round, or nearly round, with a diameter of 150-220 μm; the color of the spore becomes brown from light yellow; the spore wall has three layers, L1-L3, L1 and L2 are colorless and transparent, L3 is light yellow to brown. The hyphae is single and funnelshaped at the attachment. There was vesicle structure in the roots observed in the Olympus BX51 microscope, which shows that Mycorrhizal symbiont was established by AMF associated with Populus euphratica root. Further, Glomus mosseae can colonize in the Populus euphratica roots. But the AMF colonization rate and the infection intensity were not significantly high.

Key words: Arbuscular mycorrhizae, nested-PCR, Diversity, Populus euphratica