Species Diversity And Ecological Distribution Of Arbuscular Mycorrhizal Fungi In Desert Relict Plant Gymnocarpos Przewalskii

Gymnocarpos przewalskii Maxim(Cauyophyllaceae,Gymnocarpos Forssk.)is a perennial shrub which belongs to the ancient Mediterranean floral region and was designated as national level to protect plants in China.G.przewalskii is also the main constructive species of the rocky desert.In addition,as a relict plant of the Tertiary,it's survival and evolution of the development process is extremely important for the study of ancient Mediterranean climate and xeric plant evolution.Anxi extreme drought desert national ature reserve and Minqin Liangucheng national nature Reserve are the main distribution areas of G.przewalskii.The typical arid desert ecosystem has an important research status for physical geography and the occurrence and evolution of ancient Mediterranean floral region.The symbiotic structure of arbuscular mycorrhizal fungi(AMF)and plant roots can promote the absorption of nutrients by plants which is of great significance to the growth,development and reproduction of plants under adversity stress.Moreover,AMF can improve soil stability and promote soil material exchange by form hyphal network structure and Glomalin-related soil protein,which is valuable to the restoration and monitoring of the ecological environment.In this study,root and soil samples was collected from the rhizosphere 0-10 cm and10-20 cm of G.przewalskii in July 2018,July,September,and December 2019 across Anxi and Minqin.The ecological distribution,species diversity and community structure of AMF in the rhizosphere of G.przewalskii were studied through morphological methods combined with high-throughput sequencing.Provide a basis for interpretation of indicators of environmental change desert areas AMF data,while providing a usable way to protect fruit trees bare.The main results were as follows:1.In the two sites,G.przewalskii's root system could form a symbiotic structure with AMF at all sampling times.In Anxi,the colonization rate of AMF was 40-80% in summer of2018,and was 38-75.3% across three seasons in 2019,the density of AMF spores was 21-63(num/20 g soil).In the summer of 2018,the AMF colonization rate was 70-80%,and in the three seasons of 2019 was 47.53-71% in Minqin;the spore density was 73-314(num/20 g soil).The colonization rate of AMF was significantly positively correlated with temperature,soil humidity,total nitrogen,and EE-GGRSP;spore density was significantly positively correlated with temperature,soil humidity,organic carbon,total phosphorus,and T-GRSP.The differences in AMF colonization rate and spore density in different seasons were significant,and spore density was significantly affected by sites.2.A total of 42 AMF in 5 genera were identified soil through morphological identification in Anxi,including 18 species of Acaulospora,17 species of Glomus,and 3species of Claroideoglomus and Septoglomus,Funneliformis 1 species;8 genera and 46 species of AMF were identified from Minqin,including 18 species of Acaulospora and 17 species of Glomus,3 species of Claroideoglomus and Septoglomus,2 species of Rhizophagus,Diversispora,Funneliformis and Scutellospora were 1 species,respectively.The identification ratios of Acaulospora and Glomus in grey-brown desert soil were 45.45%and 28.14%,and the identification ratios in aeolian sandy soil were 34.69% and 33.40%,respectively.They are the dominant species of the two sites.3.Non-metric multidimensional scaling(NMDS)analysis showed that there was no significant difference in the composition of the AMF community among different root soil layers,sites and seasonal changes significantly affected the composition of the AMF community.The general trend of the AMF alpha diversity index in the two sites was higher in summer and winter than autumn;the alpha diversity index in Minqin was significantly higher than that of Anxi;the Chao1 index was significantly different in the 0-10 cm soil layer of Minqin.4.The average abundance of AMF in the two sites was significantly positively correlated with soil humidity,organic carbon,alkaline phosphatase,and T-GRSP;AMF shannon index and Chao1 index were significantly positively correlated with EE-GRSP in Minqin.Variance decomposition analysis(VPA)shows that the three explanatory variables of soil factors,climate factors,and geographic location explain 33.8% of the AMF community variation,of which geographic location alone can explain 13.4% of the AMF community variation,and soil factors can explain 6.7%,alonely.The interaction between geographic location and soil factors can explain 12.3% of the variance of AMF community variation.Although climate factors did not directly contribute to the interpretation of AMF community variation,climate factors combined with soil factors and geographic location jointly contributed to the AMF community.5.1540875 AMF sequences were obtained by high-throughput sequencing.The AMF sequence numbers of Anxi and Minqin were 812450 and 728425,respectively.1023 OTUs were detected from the two sites.Combined with NCBI,all AMF OTUs were divided into 4orders,3 families and 6 genera.The 6 genera of AMF were Glomus,Paraglomus,Septoglomus,Diversispora,Claroideglomus and Rhizophagus.Among them,Glomus was the dominant genus of the two sites,occupying a higher ecological niche.Archaeosporales was not found at the lower classification level.At the species level,11 species of Glomus,1species of Septoglomus,1 species of Rhizophagus,1 species of Paraglomus,2 species of Diversispora,and 1 species of Claroideglomus were identified.6.Principal co-ordinates analysis(PCoA)showed that geographical location significantly affected the AMF community structure,and seasonal changes significantly affected the AMF community structure of Anxi.The AMF alpha diversity varies significantly between seasons in Anxi.The AMF alpha diversity index of different sites,Minqin was significantly higher than that of Anxi in the same season.7.The between-habitat diversity of AMF was significantly positively correlated with temperature,E-GRSP,urease,soil p H,soil humidity,organic carbon,T-GRSP,total phosphorus,and total nitrogen across seasons in Anxi.Among sites,between-habitat diversity of AMF was significantly negatively correlated with soil humidity,urease,total phosphorus,organic carbon,and total nitrogen.And this index was significantly positively correlated with urease between years in Minqin.8.Distance-based redundancy analysis(db-RDA)results showed that soil urease,temperature and significantly affect the AMF community structure of Anxi;EE-GRSP significantly affects the AMF community structure of Minqin.9.The correlation between AMF and environmental factors at the species level showed that Glomus-sp.-VTX00304 was significantly negatively correlated with T-GRSP,EE-GRSP,and total phosphorus;Glomus-intraradices-VTX00105 was significantly negatively correlated with T-GRSP and organic carbon;Glomus-sp.-VTX00330,Glomus-MO-G8-VTX00130,Glomus-Glo7-VTX00214,Glomus-Yamato08-A1-VTX00100,Glomus-Glo-F-VTX00167,Glomus-viscosum-VTX00063,and unclassified?g?Glomus were significantly negatively correlated with T-GRSP;Glomus-MO-G7-VTX00199 had a significant negative correlation with total phosphorus;unclassified?o?Archaeosporales had a significant negative correlation with precipitation.Unclassified?g?paraglomus was significantly negatively correlated with total nitrogen.Unclassified?c?Glomeromycetes and Paraglomus-Glom-1B.13-VTX00308 were significantly positively correlated with the total extracted glomeromycetes in the soil.