Studies On Relationships Between Swainsonine And Fungal Endophytes In Oxytiopis Glabra Collected From Wushen Banner

Oxytropis glabra is a kind of plant species that widely distributes inInner Mongolia grassland and desert regions. Poisonous alkaloidsswainsonine is found in many plants which is harmful to livestock. However,O.glabra has important medicinal and ecological values. It would be anexcellent forage species if swainsonine is removed from the plant. Theswainsonine is also a kind of potential and valuable anticancer medicament aswell.In this research, fungal endophytes were cultured with the stem explant ofO.glabra, and the fungi were investigated by the methods of microbiologyand molecular biology. The5.8SrDNA/ITS sequences of the fungalendophytes were amplified and then sequenced. The taxonomy of the fungalendophytes was analyzed according to the results of molecular biological andmicrobiological studies. The fungal specific sequences of5.8SrDNA/ITS inindividual plants from which fungal endophytes not screened were alsoamplified from palnt total DNA and then sequenced. The swainsonineextracted both from individual plant of O.glabra and their fungal endophyteswas determined by gas chromatography. The relationship betweenswainsonine from O.glabra and the fungal endophytes in O.glabra wereinvestigated. The optimizing conditions of fungal endophyte strain OW5.3insolid medium were studied. The growth speeds of the fungal endophytes weredetected, and the swainsonine levels of the fungal endophytes were alsodetermined by gas chromatography at different culture conditions, such asdifferent carbon sources and initial pH values. Then the influences ofdifferent culture conditions to the growth speeds and the content ofswainsonine of the fungal endophytes were analyzed. The results show asfollows: 1. The5.8SrDNA/ITS sequences of the fungal endophytes wereamplified from all of the60plants collected from four different sample plots,and all of them contained swainsonine. The accurate swainsonine content wasdetermined except one.2. Sixteen fungal endophytes were isolated and cultured from O.glabra.They were the same to the fungal endophytes from O.glabra and theEmbellisia sp. L12published before in morphologic characteristics of thecolonies. Their5.8SrDNA/ITS sequences were the same to the sequences offungal endophytes submitted by Luping. Compared to the sequence ofEmbellisia sp.L12, there was only one variation site in5.8SrDNA region.Therefore, the fungal endophytes of O.glabra were considered belonging toEmbellisia. Inaddition， all of the16fungal endophytes containedswainsonine.3. The results of optimizing conditions of fungal endophyte strainOW5.3in solid medium showed that the growth speed was the fastest and thecontent of swainsonine in hyphae was the hightest when the initial pH valuewas set at7.0. The growth speed was faster when glucose was chosen as thecarbon source. The level of swainsonine in hyphae was highest when oatmealwas chosen as the carbon source.