The Structure Community And Diversity Of Arbuscular Mycorrhizal Fungi In Rhizosphere Of Hedysarum Scoparium

Hedysarum scoparium are unique sand plants within the Eurasian continent and are widely distributed in the desert regions of northwestern China.The northwestern desert belt has a very large span in China.It belongs to a typical temperate continental climate.The degree of drought from east to west gradually deepens,and the natural landscape changes along with it.From the grassland to the extremely dry desert.The unique geographical environment has created a unique flora,but also contains rich species diversity,including AM fungi.AM(arbuscular mycorrhiza)fungi are widely distributed soil microorganisms.It is an important part of ecology to understand their community composition and distribution drivers.Morphology is currently the primary means of identifying AM fungi.However,the morphology of spores of AM fungi is related to species and environmental dependence,and this morphological difference accumulates over time.This change in morphology is usually very subtle and difficult to observe by ordinary light microscopes.Scanning electron microscopy can observe the micro-morphological features of spores and accessory structures of AM fungi by capturing the electrical signals,which is helpful for the species identification of AM fungi and the determination of spores' nuances.In the natural distribution areas of the northwestern desert belt in 2015,2016,and July 2017 respectively,seven sample plots were selected to collect rhizospheric soil samples from the Hedysarum scoparium.From east to west,Ordos,Wuhai,Dengkou,Alxa,Shapotou,Minqin and Anxi.The combination of light microscopy and scanning electron microscopy was used to study the community composition,species diversity,and adaptability of desert arbuscular mycorrhizal fungi,and the correlation analysis of the environmental factors of the plots was conducted to elucidate the ecological geographical distribution of the arbuscular mycorrhizal fungi.It provides the basis for adapting to the extreme desert environment mechanism and at the same time provides assistance for desertification control.The mechanism provides the basis for helping governance of desertification.The main experimental results are as follows:1.A total of 6 genera and 44 species of AM fungi were isolated from the rhizosphere soil of Hedysarum scoparium,including 18 species of genus Acaulospora,of which 3 species were not identified,and 17 species of Glomus,of which 1 were undefined species.There were 2 species of Funinciliformis,2 species of Septoglomus,4 species of Claroideoglomus,and 1 species of Scutellospara.The distribution of genus arbuscular mycorrhizal fungi in the rhizosphere of Hedysarum scoparium was Glomus > Acaulospora > Claroideoglomus > Septoglomus > Funinciliformis > Scutellospara.The genus Glomus,Acaulospora,Claroideoglomus,and Septoglomus belonged to the common genus of the 7 plots.The genus Funinciliformis was not found only in Anxi plots.There was no discovery Scutellospara in the sites of Dengkou and Minqin.2.Acaulospora bireticulata,Acaulospora scrobiculata,Glomus pansihalos,Septoglomus deserticola,Glomus melanosporum,Glomus reticulatum,Claroideoglomus claroideum,Acaulospora mella,Glomus multicaule were the main dominant species,but no have been found common dominant species in 7 sites;Acaulospora scrobiculata,Glomus convolutum,Glomus reticulatum,and Septoglomus deserticola were common species in 7 sample plots,which were widely distributed and belong to the broad-spectrum species in desert areas.3.The arbuscular mycorrhizal community structure in the rhizosphere of Hedysarum scoparium was significantly different and could be divided into three categories.The arbuscular mycorrhizal community structure in the rhizosphere of Ordos and Alxa plots was a separate species,and the other 5 plots all formed a group,and there were significant differences among the three major groups.There was obvious spatial heterogeneity.The soil factors that caused differences in the composition of the AM fungi community in the plots varied.The effect of glomalin on Ordos plots was obvious.Acid phosphatase had a significant influence on Alxa,while other plots were significantly affected by soil pH and organic matter.4.The species abundance,spore density,and species diversity index of AM fungi in the rhizosphere of Hedysarum scoparium decreased along the longitude and gradually decreased from east to west,which was consistent with the variation trend of rainfall and soil moisture.The species abundance,spore density,species diversity index of AM fungi were significantly positively correlated with soil moisture,Shannon-Wiener index and Simpson index were positively correlated with available phosphorus,and spore density was significantly negatively correlated with organic matter.At the same time,species abundance,the diversity index and glomalin content showed a significant positive correlation with the longitude gradient.5.There were some differences in morphology of AM fungi in desert habitats compared with other habitats.For example,spores become smaller and their color deepens.There were pits or pores of different sizes on the surface of spores,and often have impurities.Spores were dry and not full.