与盾叶薯蓣细胞共生培养的内生真菌分离及其生物学特性

Isolation and characterization of endophytic fungus from Dioscorea zingiberensis C.H.Wright co-cultivated with host calli

从盾叶薯蓣根状茎中分离到一株与盾叶薯蓣细胞共生培养的内生真菌(RE0105)。测定了该菌ITS1-5.8SrDNA-ITS2序列并构建了系统发育树,发现RE0105与Libertella属形成一个类群,具有较近亲缘关系。该真菌能产生与宿主植物相同的代谢产物——薯蓣皂苷元。对RE0105培养特性研究表明:富含有机营养的培养基有利于其生长;盾叶薯蓣细胞提取物可明显刺激其生长;20μmol/L生长素NAA和2,4-D能够促进RE0105的生长。200μmol/L细胞分裂素KT和BA对RE0105生长具有一定的促进作用,但与生长素相比,细胞分裂素对RE0105生长的刺激作用较小。蔗糖、葡萄糖、果糖、乳糖、木糖和NH4NO3是RE0105生长的良好C源和无机N源,但NH4C l和(NH4)2SO4对该菌生长具有明显抑制作用,并且显著影响其形态特征。

An endophytic fungus co-cultivated by D. zingiberensis calli was isolated from the rhizome of D. zingiberensis. Phylogenetic analysis based on ITS1-5.8S rDNA-ITS2 sequence demonstrated that fungus RE0105 formed a cluster together with the genus Libertella by a good statistical support, thus they had a close similarity. The studies on the chemical characterization showed that the fungus alone could produce diosgenin. Cultural characteristics of the fungus were also investigated. Media rich in organic nutrients was propitious to the growth of fungus RE0105. Calli and calli extracts of D. zingiberensis stimulated growth of the fungus. Treatment of the fungus cultures with 20 μmol/L auxin （ NAA or 2,4-D） promoted its growth. The growth of the fungus treated with 200 μmol/L cytokinin （ KT or 6-BA） was not improved compared with the precedent one. The favorable carbon and inorganic nitrogen sources were sucrose, glucose, fructose, lactose, xylose, and ammonium nitrate. However, the growth of the fungus was inhibited and the morphology of RE0105 was changed in the presence of ammonium chloride or ammonium sulfate.