Diversity And Growth-Promoting Ability Of Endophytic Fungi In Cywmbidium Faberi

Cymbidium faberi,a Chinese orchid belonging to Cymbidium of Orchidaceae,widely distributed in China,Korea,Japan and Northwest India.However,they were mostly found in south of Shaanxi province,the Yunnan-Guizhou Plateau and the middle and lower reaches of the Yangtze River in China.C.faberi is one of Chinese orchids with a long horticulturally history in China.It was a highly appreciated ornamental plant due to its tall plant-type,zygomorphic flowers,fragrant aroma,and elegant symbolic significance.In recent years,wild resources had been being increasingly exhausted due to over-exploitation.In addition,the seed of this species was very small and difficult to germinate.Its propagation speed is slow and growth cycle is long.The wild resources protection of C.faberi was extremely urgent.Meanwhile,C.faberi had ornamental and medicinal value as well as a greater potential for further development and utilization.In this study,endophytic fungi were isolated from the roots of wild C.faberi in three sample plots(Lueyang County,Nanzheng District and Yangxian County in Shaanxi Province).The diversity of endophytic fungi in C.faberi was analyzed by high-throughput sequencing and pure culture method.The growth-promoting abilities of endophytic fungi,such as IAA activity and siderophore activity,were studied.And five endophytic fungi strains(NZ5,LY65,LG37,NZ80 and LG19)with growth-promoting ability were screened for pot culture of C.faberi.The effects of Endophytic Fungi on the growth of C.faberi were studied by adding endophytic fungi to different experimental groups and measuring the biomass and physiological indexes of C.faberi.It could provide a basis for exploiting and utilizing endophytic fungi resources of C.faberi and its growth promotion research.The main conclusions were as follows:1.The results revealed that a total of 211 517 valid sequences were obtained from 3 sampling sites in south of Shaanxi province.The samples comprised of 986 operational taxonomic units(OTUs),including 8 phyla and 113 genera.Basidiomycota was the dominant phylum and the Guehomyces was dominant genus.Though the community compositions of the sample endophytic fungi from different locations were different,there were certain significant similarities.C.faberi in Yangxian showed the most diversity,while the similarity between Lueyang and Nanzheng was the highest.In the experiment,Thanatephorus,Ceratobasidiaceae and Russulaceae were detected as mycorrhizal fungi,but the abundance was low(<0.1%),indicating that the mycorrhizal fungi had a low proportion in the endophytic fungi community of C.faberi.2.A total of 216 strains of endophytic fungi were obtained from the three plots by pure culture method,belonging to 46 genera,of which Trichoderma was dominant,and the isolation rate and frequency were 18.52% and 23.15% respectively.90 strains belonging to 26 genera including 12 unique genera of endophytic fungi was isolated in Lueyang;65 strains belonging to 21 genera including 10 unique genera of endophytic fungi was isolated in Nanzheng;61 strains belonging to 21 genera including 8 unique genera of endophytic fungi was isolated in Yangxian.Diversity index,evenness index and richness index of endophytic fungi were the highest in Lueyang.The similarity index between Lueyang and Yangxian was the highest among three sites.This result was different from that of high-throughput sequencing.The endophytic fungi isolated in the experiment contained Thanatephorus sp.and Ceratobasidium sp.belonging to mycorrhizal fungi,indicating that cymbidium in southern Shaanxi province prefers symbiosis with Thanatephorus sp.or Ceratobasidium sp..3.The growth-promoting abilities of endophytic fungi,such as IAA activity and iron carrier activity,were studied.And five endophytic fungi strains,NZ5(Trichoderma sp.),LY65(Trichoderma sp.),LG37(Hypocrea sp.),NZ80(Mucor sp.)and LG19(Nectriopsis sp.)with growth-promoting ability were screened for the pot culture of C.faberi.Five strains of fungi were cultured and added to C.faberi.Compared with the control group,the biomass and physiological indexes of the treated group of C.faberi had significant changes in varying degrees.According to the comprehensive analysis of experimental results,T1(NZ5)treatment had the most significant effect on growth promoting C.faberi.Through the pot experiment that endophytic fungi strains with growth promoting ability were used to promote the growth of C.faberi,the effect of screened growth-promoting endophytic fungi on the growth and development of C.faberi were studyed,were used to promote in order to promote the growth and development of C.faberi and provide reference for the protection of wild resources of C.faberi.