Seemüller E, Schneider B, Mäurer R, Ahrens U, Daire X, Kison H, Lorenz K H, Firrao G, Avinent L, Sears B B
Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenschutz im Obstbau, Dossenheim, Germany.
Int J Syst Bacteriol. 1994 Jul;44(3):440-6. doi: 10.1099/00207713-44-3-440.
The phylogenetic relationships of 17 phytopathogenic mycoplasmalike organisms (MLOs) representing seven major taxonomic groups established on the basis of MLO 16S ribosomal DNA (rDNA) restriction patterns were examined by performing a sequence analysis of the 16S rDNA gene. The sequence data showed that the MLOs which we examined are members of a relatively homogeneous group that evolved monophyletically from a common ancestor. In agreement with results obtained previously with other MLOs, our results also revealed that the organisms are more closely related to Acholeplasma laidlawii and other members of the anaeroplasma clade than to any other mollicutes. A phylogenetic tree based on 16S rDNAs showed that the MLOs which we examined can be divided into the following five primary clusters: (i) the aster yellows strain cluster; (ii) the apple proliferation strain cluster; (iii) the western-X disease strain cluster; (iv) the sugarcane white leaf strain cluster; and (v) the elm yellows strain cluster. The aster yellows, western-X disease, and elm yellows strain clusters were divided into two subgroups each. MLOs whose 16S rDNA sequences have been determined previously by other workers can be placed in one of the five groups. In addition to the overall division based on 16S rDNA sequence homology data, the primary clusters and subgroups could be further defined by a number of positions in the 16S rDNAs that exhibited characteristic compositions, especially in the variable regions of the gene.
通过对16S核糖体DNA（rDNA）基因进行序列分析，研究了17种植物致病性类支原体生物（MLOs）的系统发育关系，这些MLOs代表了基于MLO 16S rDNA限制性图谱建立的七个主要分类群。序列数据表明，我们所检测的MLOs是一个相对同源的群体成员，它们从一个共同祖先单系进化而来。与之前对其他MLOs的研究结果一致，我们的结果还表明，这些生物与莱氏无胆甾原体及厌氧原体分支的其他成员的关系比与任何其他柔膜菌纲细菌的关系更为密切。基于16S rDNAs构建的系统发育树表明，我们所检测的MLOs可分为以下五个主要类群：（i）紫菀黄化病菌株类群；（ii）苹果增殖病菌株类群；（iii）西部X病病菌株类群；（iv）甘蔗白条病菌株类群；（v）榆树黄化病菌株类群。紫菀黄化病、西部X病和榆树黄化病菌株类群又各自分为两个亚群。其他研究人员先前已确定其16S rDNA序列的MLOs可归入这五个类群之一。除了基于16S rDNA序列同源性数据进行总体分类外，这些主要类群和亚群还可通过16S rDNAs中一些具有特征性组成的位置进一步界定，尤其是在该基因的可变区。
