Jin T, Horgen P A
Department of Botany, University of Toronto, Mississauga, Ontario, Canada.
Curr Genet. 1993 Mar;23(3):228-33. doi: 10.1007/BF00351501.
The mitochondrial (mt) genome of Agaricus bisporus Ag50 (a heterokaryon) is a 136-kilobase (kb) circular molecule which contains a pair of large inverted repeats (IRs). Two large BAMHI fragments (B1 and B2) which contain the IR regions were further mapped. The repeated regions were determined to be approximately 7.7 kb in length. The mt small ribosomal RNA (S rRNA) gene is located adjacent to one of the repeated regions. Orientational isomers, generated by homologous recombination between the repeated regions, were not observed in mtDNA extractions from Ag50 mycelium (liquid culture) or from Ag50 fruit bodies. We also did not observe any orientational isomers in Ag50HA or Ag50HB, two homokaryons somatically isolated from Ag50. DNA homologous to the Ag50 mt repeated regions was observed in ten other isolates of Agaricus including four isolates of A. bisporus, two isolates of A. subperonatus, two isolates of A. subfloccosus, one isolate of A. bitorquis, and one isolate of A. pattersonae. The repeated regions and the small unique regions in two other heterokaryotic strains of A. bisporus, Ag2 and Ag85, were physically mapped. The repeated regions in these two strains are also in the inverted forms. Restriction endonuclease mapping indicated that the two copies of the IR in Ag85 were not identical.
双孢蘑菇Ag50（一种异核体）的线粒体（mt）基因组是一个136千碱基（kb）的环状分子，其中包含一对大的反向重复序列（IRs）。进一步绘制了包含IR区域的两个大的BAMHI片段（B1和B2）的图谱。重复区域的长度约为7.7 kb。线粒体小核糖体RNA（S rRNA）基因位于其中一个重复区域附近。在从Ag50菌丝体（液体培养物）或Ag50子实体中提取的mtDNA中，未观察到由重复区域之间的同源重组产生的方向异构体。我们在从Ag50体细胞分离得到的两个同核体Ag50HA和Ag50HB中也未观察到任何方向异构体。在双孢蘑菇的其他十个分离株中观察到了与Ag50 mt重复区域同源的DNA，其中包括四个双孢蘑菇分离株、两个亚柄蘑菇分离株、两个亚絮状蘑菇分离株、一个双扭蘑菇分离株和一个帕特森蘑菇分离株。对双孢蘑菇的另外两个异核体菌株Ag2和Ag85中的重复区域和小的独特区域进行了物理图谱绘制。这两个菌株中的重复区域也呈反向形式。限制性内切酶图谱显示，Ag85中IR的两个拷贝并不相同。
