Abstract:

【Objective】 The fungal endophytes were isolated from three locoweeds Oxytropis sericopetala, Oxytropis glacialis and Astragalus strictus in Tibet. 【Method】 The swainsonine isolated from the endophytes was analyzed with thin-layer chromatography, gas chromatography and gas chromatography-mass spectrometry. The ITS and IGS regions of fungi were amplified by polymerase chain reactions. In addition to the sequences of ITS regions from endophytes, the phylogenetic tree based on the ITS sequences was constructed to determine the taxon of the endophytic fungi. The amplified products of IGS regions from endophytes were digested using restriction enzymes and the digested products were analyzed. 【Result】 Four swainsonine-producing fungal endophytes were isolated from three species of locoweeds. The morphology of fungi and homology of ITS sequences was closely related to that of Embellisia spp. Four isolates were named Embellisia oxytropis based on the phylogenetic tree. 【Conclusion】 Analysis of the ITS sequences and the digested IGS fragments indicated that four endophytes were closely related species. However, the intraspecific variation was present among the fungal endophytes from different host plants and the isolates may be different subspecies of Embellisia oxytropis. The research is important to explore the SW biosynthesis mechanism of endophytes and has provided a novel knowledge for the elimination of animal locoism and a reasonable utilization of locoweeds.

Key words: locoweed, swainsonine, fungal endophyte, Embellisia oxytropis