title: A global picture of tRNA genes in plant genomes.
abstract: 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.
authors: Institut de Biologie Moléculaire des Plantes, UPR 2357-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg Cedex, France.
authors: Morgane
authors: M
authors: Michaud
authors: Valérie
authors: V
authors: Cognat
authors: Anne-Marie
authors: AM
authors: Duchêne
authors: Laurence
authors: L
authors: Maréchal-Drouard
mesh_terms: D021581:Active Transport, Cell Nucleus; D001483:Base Sequence; D000460:Chlorophyta / Q000235:genetics; D019143:Evolution, Molecular; D017343:Genes, Plant; D018745:Genome, Plant; D007438:Introns; D019684:Magnoliopsida / Q000235:genetics*; D008928:Mitochondria / Q000235:genetics; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011544:Pseudogenes; D018749:RNA, Plant / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics*; D017422:Sequence Analysis, DNA; D020086:Short Interspersed Nucleotide Elements; D016385:TATA Box
chemical_list: D018749:RNA, Plant; D012343:RNA, Transfer