Diversity And Application Of Endophytic Fungi From Roots Of Dendrobium (Orchideace)

Dendrobium is one of the largest genus in Orchid family, which has high economic values as both famous ornamental and medicinal plants. In nature, it needs to associate with fungi for growth and reproduction. In t is study, endophytic fungi from roots of12species of Dendrobium were isolated and identified.Through tissue cultured seedlings, the effects of3strains of orchid mycorrhizal fungi on Dendrobium officinale was studied. The main results are as follows:(1)152strains of endophytic fungal were isolated from roots of12Dendrobium species in Guangxi and Guizhou habitats with three kinds of separation methods and three kinds of media. Using morphological and ITS rDNA molecular identification method, these fungi were identified into22orders,9classes,3phylum. Comparing the diversity of endophytic fungi isolated by different methods and media, the Shannon-Wiener diversity of spotting method and FIM medium reached2.79and2.54separately. Comparing the endophytic fungi of the same Dendrobium species isolated from different habitats and epiphytic types, the result showed that the diversity of endophytic fungi in Guangxi habitat was much higher than Guizhou, and the in-tree-epiphytic type was higher than that of lithophytic type. The result showed that habitats and epiphytic type can affect the diversity of endophytic fungi of Dendrobium.(2) Screened the optimum medium for strengthen-seedling and rooting of D. officinale. Seedlings of D. officinale with1-2leaves were cultivated after11weeks in three kinds of media, and the seedlings growed on MS+0.34g/L KNO3+100g/L potato extract+2.4g/L plant gel+30g/L sucrose were better. The average height, stem diameter, fresh weight increased3.61cm,4.06mm,2.67mm respectively. The new roots and new buds were12.55and6.20respectively, the average length of new roots was2.03cm, significantly higher than the other two media. (3) Screened the optimum medium for transplanting of D. officinalc. After90d, the survival rate of seedlings on the medium which contained perlite1cm, cents soil1cm, pine bark1cm and fresh moss2cm reached75.00%, the average fresh weight, plants’height, stem diameter increased108mg.7.50mm,0.260mm respectively. The average number of new roots was1.43, higher than the medium which contained1/3cm peanut shells,1/3cm limestone,1/3cm vermiculite and fresh moss2cm.(4) Screened the optimum fungal inoculum and the inoculating method for transplanting of D. officinalc seedling. Three strains of mycorrhizal fungi were made into single liquid fungal inoculum and the concentration was4g/L. There were two inoculating methods for each mycorrhizal fungus:dipping and irrigating. After90d, the transplanting survival rate of tissue culture seedlings, the number of new roots, the rate of shooting, the average of plants’height, stem diameter, fresh weight deal with3kinds of mycorrhizal fungi were extremely higher than the controls. Comparing different inoculating method for the same fungus, dipping treatment was higher than irrigating treatment. The result showed that three strains of fungi with dipping treatment had a good application prospect for transplanting of D. officinale seedling.