Mycorrhizal Fungi And Symbiotic Seed Germination Of Four Paphiopedilum Species

The genus Paphiopedilum has unique colors,fancy patterns and high ornamental value,however,due to the destruction of natural habitat and human excessive collection,the wild orchid population is threatened.Because of a lack of endosperm in the seed,specific fungi are needed for the germination under the natural conditions.At present,the method of non symbiotic germination is used for the propagation of the genus Paphiopedilum,but the survival rate of the seedlings obtained by asymbiotic seed germination is low.Therefore,4 species of Paphiopedilum plants were selected as the research object,including Paphiopedilum charlesworthii,P.concolor,P.micranthum and P.armeniacum.The morphology and structure of mycorrhizal fungi in wild adult Paphiopedilum plants were observed by field sampling.Based on the in situ germination and the symbiotic germination experiment,the symbiosis relationship between the Paphiopedilum plants and mycorrhizal fungi were discussed.The effects of mycorrhizal fungi on the growth and development of tissue culture seedlings were studied by means of symbiotic culture and paraffin sections.The main results were as follows:1.The basic structure of several kinds of Paphiopedilum plants had typical monocotyledon root,root cortex cells were distributed in the form of mycorrhizal fungi "pelotons" structure.Compared with the terrestrial orchids including P.micranthum and P.armeniacum,the hemiepiphytic ones of P.charlesworthii and P.concolor had longer roots,and there were more cortical cells containing pelotons.2.Isolation and identification of four species of mycorrhizal fungi involved in a total of 9 families of fungi and 1 unknown Basidiomycete.The isolation frequency of the fungi from Chaetomium,Fusarium and Tulasnellaceae was higher.The diversity of mycorrhizal fungi was related to its habitat environment.3.The results of in situ germination test showed that the seed germination rate of Paphiopedilum was difficult in nature.The germination rate of P.charlesworthii was 0.139%4.In vitro symbiotic seed germination of P.charlesworthii,P.concolor and P.micranthum were carried out.The resuits showed that the mycorrhizal fungi FJ786676 isolated from the accession of P.armeniacum could promote seed germination and development of P.charlesworthii and P.concolor to stage 25.The different strains of mycorrhizal fungi and tissue cultured seedlings of P.charlesworthii were cultured in inoculums production.Results showed that the mycorrhizal fungi had effects on the growth rate,root activity,soluble sugar content and chlorophyll content,and the effect of Tulasnellaceae on the growth of tissue culture seedlings was significant Two ways of the invasion of the root cortex cells by symbiotic fungi were observed.In this study,the factors affecting the composition of mycorrhizal fungi were analyzed and discussed.The mycorrhizal fungi which could promote the seed germination of four Paphiopedilum species were trapped and cultured.The effects of mycorrhizal fungi on the growth and development of tissue culture seedlings of P.charlesworthii were verified.Two ways of mycorrhizal fungi invading the root of P.charlesworthii were observed.It was significative for the establishment of the symbiotic germination system of P.charlesworthii and P.concolor,and the realization of P.charlesworthii mycorrhizal cultivation.