Study On The Coupling Relationship Of The Recession Between The Endangered Plants-Ammopiptanthus Mongolicus And Its Fungal Community

West Ordos National Nature Reserve is a type of nature reserve in the desert ecosystem in which ancient relict and endangered plants and desert ecological system have been protected.It is located in the northwest of the Inner Mongolia Autonomous Region,in the long strip between the east coast of the Yellow River and the western edge of the Ordos Plateau.It is an ecologically fragile area in the desert area of Northwest china.Ancient Mediterranean relict plants which are endangered and protected by the state are rich in this nature reserve.This nature reserve which is located in the transition zone of grassland to desert has different combinations of landscape types,and has rare and endangered plants which accounts for nearly 2/3 of all plant species,these plants are constructed and dominant species in this area,and form a rare type of landscape in arid desert area.West Ordos National Nature Reserve is one of the hot spots of biodiversity research in arid areas of Northwest china.The relic plant of third century-Ammopiptanthus mongolicus which originated in ancient Mediterranean has severely re-accessioned because of environment changing and human destruction.The real causes of the recession of A.mongolicus and how to protect them effectively have been paid close attention by academic circles.In this study,the recession degrees of A.mongolicus have been divided using thermal imaging,and a high throughput sequencing method has been used to investigate the endophytic fungi in roots and the soil fungi in rhinoceros of A.mongolicus.The main conclusions are as follows:(1)the diversity of endophytic fungi in roots of A.mongolicus from five different habitats varies: the foot of the hill> the hillside> the roadside > the riverside >the chemical plant.At the phylum level,fungi of Basidiomycota are dominant in the roots of A.mongolicus from the foot of the hill,chemical plant,and the hillside,fungi of Ascomycota are dominant in the roots of A.mongolicus from the riverside.Fungi of Ascomycota and Basidiomycota both have large proportion in the roots of A.mongolicusfrom the roadside.The community structure of endophytic fungi in roots of A.mongolicus from 5 habitats was very significant at the levels of genus and family.At the level of genus,among dominant genera of endophytic fungi(abundance more than1%)from 5 different habitats,the ratio of saprophytic fungi or parasitic fungi to symbiotic fungi varies greatly,saprophytic fungi or parasitic fungi have highestproportion in roots of A.mongolicus from the riverside,symbiotic fungi has the highest proportionin roots of A.mongolicus from the hillside.The constructed fungi in roots of A.mongolicus from 5 habitats are Tomentella,Tricholoma,Fusarium and Sebacina.(2)The composition of endophytic fungi in roots of A.mongolicus from different recession levels is significantly different at the levels of phylum,family and genus.Fungi belonged to 6 genera among Top10 genera including Agaricus,Tomentella,Tricholoma,Fusarium,Inocybe,and Tuber distributes in roots of A.mongolicusfrom all levels of recession.Parasitic or saprophytic fungi and symbiotic fungi distributes in roots of A.mongolicus from all levels of recession.The ratio of saprophytic fungi or parasitic fungi to symbiotic fungi varies in different recession levels,it increases dramatically as the recession level increases,which can be one reason that caused the recession of the community of A.mongolicus.Soil organic matter and soil bulk densityhave synergistic effects,they havepositive correlation with Agaricus,Inocybe,Fusarium,Penicillium and Amphinema,and have negative correlation with Tricholoma,Tomentella and Tuber.(3)Endophytic fungi in roots and soil fungi in rhizosphere of A.mongolicus from the same recession level are significantly different on the composition.Symbiotic fungi in rhizosphere are less than in roots.Among Top 10 genera of endophytic fungi,Agaricus?Inocybe?Tomentella?Tricholoma?Tuber?Amphinema?Sebacina?Ilyonectria have not been found in rhizosphere.Two shared fungal genera in roots and rhizosphere including Fusarium and Penicilliumincreases dramatically in rhizosphere.(4)The composition of soil fungi in rhizosphere of A.mongolicus from different recession levels is significantly different at the level of phylum,family and genus.Among the Top10 fungal genera,saprophytic or parasitic fungi are dominant,and the symbiotic fungi are less.Organic matter and soil bulk density have great effect on the composition of soil fungi in rhizosphere of A.mongolicus,are positively related to saprophytic or parasitic fungi,the proportion of Fusarium,Penicillium,Gibberella,Alternaria and Phomaincreases in the recessional A.mongolicus,which means high content of organic matter and high soil bulk density are beneficial for the growth of saprophytic or parasitic fungi.(5)In mixed community of A.mongolicus and Zygophyllum xanthoxylon,the richness and diversity of endophytic fungi are higher than in pure community of both plants,fungi of Basidiomycota are dominant in mixed and pure community.There issignificant differences on fungal composition at the family and genus level.At the genus level,symbiotic fungi in roots of A.mongolicusand Zygophyllum xanthoxylon in mixed community are higher than in respectively pure communities,parasitic orsaprophytic fungi decreases,however.Endophytic fungiin roots of A.mongolicusand Zygophyllum xanthoxylon in mixed communityare similar on the composition,which can be one of the reason that the area of mixed community of those two plants increases.(6)In this study,6 endophytic fungi have been isolated and cultured.They are different in colony color,air producing hypha and other aspects.These 6 strains belong to the genera of Clonostachys and Fusarium after molecular identification,among them,5 are Fusarium and 1 isClonostachys.4 inoculants have been obtained in the liquid culture.The results show that seedlings of A.mongolicus have not been subjected to the pathogenicity after the inoculation of the four liquid strains.The role of Fusarium to A.mongolicus is still to be further studied,Clonostachys as potentialstrain of biocontrol remains to be explored.(7)In this study,high throughput sequencing analysis has beenfirstly carried out to study the endophytic fungi in roots and the soil fungi in rhizosphereof A.mongolicus.A large number of symbiotic fungal taxa which have been commonly reported as ectomycorrhizal fungal taxa appeared in roots of A.mongolicus,whether these symbiotic fungal taxa form symbiotic organization,and provide the necessary nutrients and moisture to A.mongolicus needs further study in the future.