Warren Jessica M, Ceriotti Luis F, Sanchez-Puerta M Virginia, Sloan Daniel B
Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, AZ, USA.
Howard Hughes Medical Institute, Chevy Chase, MD, USA.
Mol Biol Evol. 2025 Feb 3;42(2). doi: 10.1093/molbev/msaf025.
Plant mitochondrial genomes (mitogenomes) experience remarkable levels of horizontal gene transfer, including the recent discovery that orchids anciently acquired DNA from fungal mitogenomes. Thus far, however, there is no evidence that any of the genes from this interkingdom horizontal gene transfer are functional in orchid mitogenomes. Here, we applied a specialized sequencing approach to the orchid Corallorhiza maculata and found that some fungal-derived tRNA genes in the transferred region are transcribed, post-transcriptionally modified, and aminoacylated. In contrast, all the transferred protein-coding sequences appear to be pseudogenes. These findings show that fungal horizontal gene transfer has altered the composition of the orchid mitochondrial tRNA pool and suggest that these foreign tRNAs function in translation. The exceptional capacity of tRNAs for horizontal gene transfer and functional replacement is further illustrated by the diversity of tRNA genes in the C. maculata mitogenome, which also include genes of plastid and bacterial origin in addition to their native mitochondrial counterparts.
植物线粒体基因组（线粒体基因组）经历了显著水平的水平基因转移，包括最近发现兰花在古代从真菌线粒体基因组中获得了DNA。然而，到目前为止，没有证据表明这种跨王国水平基因转移中的任何基因在兰花线粒体基因组中具有功能。在这里，我们对兰花珊瑚兰应用了一种专门的测序方法，发现转移区域中一些真菌来源的tRNA基因被转录、转录后修饰并进行了氨酰化。相比之下，所有转移的蛋白质编码序列似乎都是假基因。这些发现表明，真菌水平基因转移改变了兰花线粒体tRNA库的组成，并表明这些外来tRNA在翻译中发挥作用。珊瑚兰线粒体基因组中tRNA基因的多样性进一步说明了tRNA进行水平基因转移和功能替代的特殊能力，除了其原生线粒体对应基因外，还包括质体和细菌来源的基因。
