Institut de Biologie Moléculaire des Plantes, UPR 2357-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg Cedex, France.
Plant J. 2011 Apr;66(1):80-93. doi: 10.1111/j.1365-313X.2011.04490.x.
Although transfer RNA (tRNA) has a fundamental role in cell life, little is known about tRNA gene organization and expression on a genome-wide scale in eukaryotes, particularly plants. Here, we analyse the content and distribution of tRNA genes in five flowering plants and one green alga. The tRNA gene content is homogenous in plants, and is mostly correlated with genome size. The number of tRNA pseudogenes and organellar-like tRNA genes present in nuclear genomes varies greatly from one plant species to another. These pseudogenes or organellar-like genes appear to be generated or inserted randomly during evolution. Interestingly, we identified a new family of tRNA-related short interspersed nuclear elements (SINEs) in the Populus trichocarpa nuclear genome. In higher plants, intron-containing tRNA genes are rare, and correspond to genes coding for tRNA(Tyr) and tRNA(Mete) . By contrast, in green algae, more than half of the tRNA genes contain an intron. This suggests divergent means of intron acquisition and the splicing process between green algae and land plants. Numerous tRNAs are co-transcribed in Chlamydomonas, but they are mostly transcribed as a single unit in flowering plants. The only exceptions are tRNA(Gly) -snoRNA and tRNA(Mete) -snoRNA cotranscripts in dicots and monocots, respectively. The internal or external motifs required for efficient transcription of tRNA genes by RNA polymerase III are well conserved among angiosperms. A brief analysis of the mitochondrial and plastidial tRNA gene populations is also provided.
尽管转移 RNA（tRNA）在细胞生命中具有重要作用，但对于真核生物（尤其是植物）在全基因组范围内的 tRNA 基因组织和表达知之甚少。在这里，我们分析了五种开花植物和一种绿藻中 tRNA 基因的含量和分布。植物中的 tRNA 基因含量是同质的，并且主要与基因组大小相关。核基因组中存在的 tRNA 假基因和类细胞器 tRNA 基因的数量在不同植物物种之间差异很大。这些假基因或类细胞器基因似乎是在进化过程中随机产生或插入的。有趣的是，我们在杨属基因组中鉴定出一种新的 tRNA 相关短散布核元件（SINE）家族。在高等植物中，内含子含有的 tRNA 基因很少，并且对应于编码 tRNA(Tyr)和 tRNA(Mete)的基因。相比之下，在绿藻中，超过一半的 tRNA 基因含有内含子。这表明绿藻和陆地植物之间存在不同的内含子获取方式和剪接过程。在衣藻中，许多 tRNAs 是共转录的，但在开花植物中，它们大多作为一个单元转录。唯一的例外是双子叶植物和单子叶植物中的 tRNA(Gly)- snoRNA 和 tRNA(Mete)- snoRNA 共转录物。RNA 聚合酶 III 有效转录 tRNA 基因所需的内部或外部基序在被子植物中高度保守。还提供了对线粒体和质体 tRNA 基因群体的简要分析。
