| Anxi extremely drought desert nature reserve is located in Guazhou,Gansu,which is the only nature reserve in China that focuses on extremely arid desert ecosystems and biodiversity.The region is typical and representative throughout the ancient Mediterranean.Symegma Regelii,Reumuria Songarica,Nitraria Sphaerocarpa,Ephedra Przewalskii and Salsola Posserinagen are typical zonal vegetation forming plant patches in desert ecosystems.These plants are of great significance for wind and sand fixation,vegetation reconstruction,and ecosystem stability.Arbuscular mycorrhiza(AM)fungi is the symbiosis with plants under drought stress,which can improve nutrients absorption of plant,promote plant growth and increase plant resistance of drought and pathogens.AM fungus forms mycelium network and secretes glomalin to stabilize the soil structure,which is important to material exchange and ecological restoration.In this experiment,root samples and soil samples of the 0-10 cm and 20-30 cm plant rhizosphere were collected from Anxi extremely arid desert natural reserve in July 2018 and July 2019.The objective of this study was to elucidate AM fungal community composition,ecological distribution and the ecological effect of soil factors in the extremely dry desert vegetation within morphology and high-throughput sequencing methods,and to provide a basis for the discovery of AM fungal resources and the restoration of desert vegetation.The main results are as follows:1.The root of five plants were infected by AM fungi to form mycelium and vesicle,and the main structure was mycelium.The total colonization intensity was up to 31.6% and 25.9% in N.sphaerocarpa in 2018 and 2019,and the minimum was 2.3%(S.posserinagen)and 3.8%(S.regelii).The hyphae infection rate and total colonization rate were positively correlated with easily extractable glomalin and total glomalin;vesicle colonization rate was significant positive correlation with nitrate nitrogen;the colonization intensity was positively correlated with ammonium nitrogen,available phosphorus,easily extractable glomalin and total glomalin.2.A total of 50 AM fungal species were isolated from 5 plants,namely 21 species of Glomus,11 species of Acaulospora,8 species of Scutellospora,2 species of Funneliformis,Claroideoglomus and Rhizophagus,1 species of Gigaspora,Paraglomus,Entrophospora and Diversispora.The proportions of Glomus were 72.9% and 76.3% in 2018 and 2019,respectively,and they were the dominant species in the Anxi extreme arid desert nature reserve.3.NMDS analysis showed that the AM fungal community composition differed significantly among the five host plants,and there was no difference between the rhizosphere of 0-10 cm and 20-30 cm in the same plant.The spore density,Shannon Wiener index,Simpson index,and species evenness of AM fungi was difference significantly within different plants,and that of 0-10 cm was higher than 20-30 cm.4.Mantel Test showed that soil factors,host plants,and interannual differences significantly and directly influenced AM fungal communities,spore density,species diversity and evenness.The AM fungal community and spore density had a significant positive correlation with organic carbon,nitrate nitrogen,total glomalin,and humidity.5.Variance partition indicated that host plants,soil enzyme activity and mineral nutrients explained 35.4% and 60.7% of the total variation of AM fungal community changes in the rhizosphere of 0-10 cm and 20-30 cm,respectively.6.High-throughput sequencing geted 1033652 sequences,200 AM fungal OTUs.By blast match,it divided into 4 family 4 genera,namely Glomus,Paraglomus,unclassified Archaeosporales and unclassified Glomeromycetes.At the genera level,Glomus and Paraglomus were the main genus of AM fungi.And at the species level,Glomus microaggregatum had the highest relative abundance.7.Lefse multi-level species hierarchy analysis showed that OTU12 and OTU15 were significantly enriched in E.przewalskii,and OTU4,OTU22,OTU31,OTU41,OTU44,and OTU48 were significantly enriched in N.sphaerocarpa,and AM fungi species relative abundance was significantly different among different plants8.Correlation heat maps indicated that AM fungal species were significantly associated with soil factors.Unclassified Glomeromycetes was significantly positively correlated with humidity and pH.Unclassified Glomus was significantly negatively correlated with humidity and significantly positively correlated with acid phosphatase.Glomus-ef.microaggregatum-VTX00104 was significantly positively correlated with urease.Glomus-sp-VTX00330 was significantly negatively correlated with humidity.Unclassified Paraglomus was significantly negatively correlated with soil organic carbon.Paraglomus-Glom-1B.13-VTX00308 was significantly negatively correlated with available phosphorus. |
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