Study On The Symbiotic Development With Endophytic Fungi Of Cymbidium Tortisepalum Var.Longibracteatum

Cymbidium tortisepalum var.longibracteatum is a unique national class?protected plant in China and the whole life history of Cymbidium tortisepalum var.longibracteatum needs to establish symbiotic relationship with specific fungi.But the species of symbiotic mycorrhizal fungi and the conditions for symbiotic development of Cymbidium tortisepalum var.longibracteatum are still unclear.Through separating,purificating,and screening the beneficial endophytic Fungi of Cymbidium tortisepalum var.longibracteatum,the experiment of symbiosis culture was carried out to explore the way to realize the symbiotic development of Cymbidium tortisepalum var.Longibracteatum.The main findings are as follows:(1)20 endophytic fungi were isolated from the wild Cymbidium tortisepalum var.longibracteatum in Bazhou District,Bazhong City,Tongjiang County of Bazhong City and Dachuan District of Dazhou City,Sichuan Province.The morphological characteristics of endophytic fungi were observed and compared.Preliminary identification of 20 endophytic Fungi belonging to Fusarium sp,Cylindrocarpon sp and Epulorhiza sp.(2)The 20 endophytic fungi isolated were cultured symbiotically with the seeds and rhizomes of Cymbidium tortisepalum var.Longibracteatum respectively.Three endophytic fungi that could promote the differentiation of Cymbidium tortisepalum var.longibracteatum rhizomes and produce adventitious buds were found,respectively:CJ3,CJ13,CJ20..The microscopic and ultrastructural observation showed that the hyphae invaded into the rhizomes of Cymbidium tortisepalum var.longibracteatum after the infection of CJ3,CJ13,CJ20,and the hyphae entered into the cortex cells through the cell space,and formed globular granular substances in the cells.Finally,microfilaments were formed and digested in cortical cells.(3)After mycorrhizal treatment by simulating the symbiosis of the original habitat of Cymbidium tortisepalum var.longibracteatum,the growth rate of fresh weight of tufted rhizome was the highest(52.48%),which was significantly higher than that of other growth stages.All three endophytic fungi of CJ3,CJ13,CJ20 could promote the growth and development of rhizome,and the growth rate of fresh weight of rhizome treated with CJ13was the highest(56.13%)which was significantly higher than that of CJ20 and CJ3 bacterial strain inoculated with rhizome(49.76%and 31.08%).The growth rate of fresh weight of the three bacterial strains after inoculation was significantly higher than that of the control(16.63%).When inoculated with CJ13,the growth rate of fresh weight of rhizome of Cymbidium tortisepalum var.longibracteatum in soil nutrient solution water(40%~60%)was significantly higher than that in other habitats.After symbiosis culture in simulated primary habitat,the rate of fresh weight increase of rhizome of Cymbidium tortisepalum var.longibracteatum treated with mycorrhizal treatment was significantly higher than that of control(no fungi inoculated).The most suitable conditions for simulating the primary habitat growth of rhizome were as follows:tufted rhizome_+CJ13+soil nutrient solution+water(keeping soil moisture 40%~60%).