The Structure Community And Diversity Of Arbuscular Mycorrhizal Fungi In Rhizosphere Of Three Desert Plants

Arbuscular mycorrhizal(AM)fungi are a principal element of the rhizosphere microflora in natural ecosystems,and play an critical role in the restoration and reconstruction of fragile vegetation or degraded ecosystems,and in the preservation of plant biodiversity and ecosystem functioning.Hedysarum laeve Maxim(Leguminosae),Artemisia ordosica Krasch(Compositae)and Psammochloa villosa(Trin.)Bor(Gramineae)are common and dominant arido-active species of the Mu Us sandlands.Thus,they play important roles in fixing shifting sand and conserving biodiversity in the desert.The spatial diversity and distribution of AM fungi were investigated at the Ordos study site located in Mu Us sandland,northwest China.Soils to 50 cm depth in the rhizospheres of Hedysarum laeve,Artemisia ordosica and Psammochloa villosa in July 2015 and 2016 by combining the morphological and high–throughput sequencing methods.We examined the connection of plant species,soil factors,and the range of soil depth on these fungi to elucidate the significance of AM associations in the desert ecosystem.For the effective containment of desertification process,the restoration of vegetation in desert areas to provide a reference.The main results are as follows:1.A total of 47 AM fungal species were isolated from the tested soil samples.The composition of AM fungal genera from different soil depths and plants varied.Of these,a high proportion and generic abundance of Glomus,Acaulospora and Scutellospora was found in three plants.The other genera,such as Diversispora,Gigaspora,Sclerocystis and Racocetra,were rare and only found in shallow soil layers.Some of the AM fungi are widely distributed,such as A.bireticulata,A.excauata,A.lavis,G.convolutum,G.melanosporum,F.geosporum,and Scu.nigra,etc.in the AM fungi communities Abundance.Gigaspora decipiens,G.pansihalos,G.sp1,Ambispora gerdemannii,Rh.diaphanus,Glomus dimorphicum,G.multicaule,G.pustulatum,Rh.intraradices,Sclerocystis sp.are rare species or rare species that appear only in some plants.2.The results showed that the spores of A.bireticulata,A.dilatata,G.convolutum,and Scu.nigra were significantly smaller than those of the ecosystems such as farmland and other ecosystems.Several AM species surface was appeared irregularly and inhomogenously pits and scratches.The rough surface was flaky,with attachments.The spores also had different characteristics in different plants,such as A.bireticulata tend to gray and unfilled in P.villosa.3.AM fungal diversity and distribution differed significantly among the three host plants and the five soil layers.Spore density and species richness had a significant positive correlation with soil total phosphorus,and negatively with soil pH.NMDS,PerMANOVA and SEM analysis demonstrated that host plants species and soil depth significantly and directly influenced the structure of AM fungal communities.4.One of the advantages of using soil is that it represents a more cost efficient way to account for host specificity of AMF taxa.After filtering out chimeras,a total of 130298 AM fungal reads were matched against 73 AM fungal OTUs from four families in the updated reference sequence set(MaarjAM database).Species richness?Simpson index?Chao1 index and ACE index are closer in H.laeve and A.ordosica,and significantly greater than P.villosa.The phylogenetic diversity index in H.laeve is higher than A.ordosica and significantly higher than P.villosa.5.The NMDS analysis showed that the host plant species could significantly affect the AM fungal community structure,but the effect of soil depth was not significant.The correlation analysis between the diversity indices of AM fungi and the host plant species,soil depth and soil factor was statistically significant.The abundance,Simpson index,Chao1 index and ACE index were significantly correlated with the host plants,but correlated with soil depth is not significant.Construction of SEM model analysis showed that host plant species,soil carbon and nitrogen ratio and soil moisture were the main factors affecting AM fungi community.