Ku Chuan, Lo Wen-Sui, Kuo Chih-Horng
Institute of Plant and Microbial Biology; Academia Sinica; Taipei, Taiwan.
Mob Genet Elements. 2013 Sep 1;3(5):e26145. doi: 10.4161/mge.26145. Epub 2013 Aug 20.
Phytoplasmas are uncultivated phytopathogenic bacteria that cause diseases in a wide range of economically important plants. Through secretion of effector proteins, they are able to manipulate their plant hosts to facilitate their multiplication and dispersal by insect vectors. The genome sequences of several phytoplasmas have been characterized to date and a group of putative composite transposons called potential mobile units (PMUs) are found in these highly reduced genomes. Recently, our team reported the genome sequence and comparative analysis of a peanut witches' broom (PnWB) phytoplasma, the first representative of the phytoplasma 16SrII group. Comparisons between the species phylogeny and the phylogenies of the PMU genes revealed that the PnWB PMU is likely to have been transferred from the 16SrI group. This indicates that PMUs are not only the DNA unit for transposition within a genome, but also for horizontal transfer among divergent phytoplasma lineages. Given the association of PMUs with effector genes, the mobility of PMUs across genomes has important implications for phytoplasma ecology and evolution.
植原体是一类尚未能人工培养的植物致病细菌,可致使多种具有重要经济价值的植物患病。通过分泌效应蛋白,它们能够操控其植物宿主,以便借助昆虫媒介实现自身的增殖与传播。截至目前,已有数种植原体的基因组序列得到了表征,并且在这些高度精简的基因组中发现了一组被称为潜在移动单元(PMU)的假定复合转座子。最近,我们的团队报道了花生丛枝病(PnWB)植原体的基因组序列及比较分析,它是植原体16SrII组的首个代表。物种系统发育与PMU基因系统发育之间的比较表明,PnWB PMU可能是从16SrI组转移而来的。这表明PMU不仅是基因组内转座的DNA单元,也是不同植原体谱系间水平转移的DNA单元。鉴于PMU与效应基因的关联,PMU在基因组间的移动性对植原体生态学和进化具有重要意义。