Detection and characterization of DNA plasmids from the shiitake mushroom, Lentinula edodes

本研究的目的是研究DNA质粒与香菇（Lentinula edodes, Berk.）的关系。并描述它们的一般性质。对110株双核菌株（90株来自不同工作区域的天然分离株和21株商业菌株）进行质粒存在性调查。这些菌株中约有80%被确定为可获得一种或多种不同的DNA质粒。检测到的质粒分别为pLE1 （9.0kb）、pLE2 （11.1kb）、pLE3A （9.8kb）、pLE3B （10.8kb）、pLE3C （12.1kb）和pLE3D (12.3kb) 6种。杂交分析表明，pLE1和pLE2是不同同源群的不同质粒类型，其余4种质粒是属于另一个共同同源群的变异类型。任何这样的质粒都与宿主和非宿主的核和线粒体基因组dna没有同源性。对这些质粒的限制性内切分析和电镜分析表明它们呈线性结构。由于这6个质粒在两性杂交中均为单亲本传递，因此它们可能位于细胞质中。从6个质粒在白桦自然居群中的分布来看，pLE1和pLE2在地理上分布广泛，而其他4个质粒在地理上不同的自然居群中是唯一的。根据质粒的地理分布格局，推测香菇的祖先区在南太平洋。

The aim of this study is to examine the association of DNA plasmids with the shiitake mushroom, Lentinula edodes (Berk.) Pegler and to describe their general properties. A survey of a total of one hndred and eleven dikaryotic strains (ninety natral isolates collected from geographically different workd regions and twenty-one commercial strains) for the presence of plasmids was carried out. About 80% of thesestrains employed were determined to harvor one or more different kinds of DNA plasmids. The plasmids detected were the six kinds of designated pLE1 (9.0kb) , pLE2 (11.1kb) , pLE3A (9.8kb) , pLE3B (10.8kb) , pLE3C (12.1kb) , and pLE3D (12.3kb) .Based on hybridization analysis, it was suggested that pLE1 and pLE2 were distinct plasmid types of different homology groups to each other, and the remaining four kinds of plasmids were variant types belonging to another, the third, common hoology group. Any of such plasmids gave no homology with their host's and non-host's nuclear and mitochondrial genome DNAs. Restriction analysis and electron microscopy on these plasmids indicated that they are linear in form. Since all of the six plasmids were transmitted uniparentally in sexual crosses, they were suggested to locate in cytoplasm. Considering the distribution of the six plasmids in natural populations of L.edodes, pLE1 and pLE2 each were known to show geographically wide distribution, but the other four plasmids were present to be uniqe for each of geographically distinct natural populations. From the geographical distribution pattern of plasmids, it was presumed that the ancestral area for shiitake mushroom is in the South Pacific.