Institute of Biotechnology, Viikki Biocenter, University of Helsinki, P.O. Box 65, Helsinki FIN-00014, Finland; Biotechnology and Food Research, MTT Agrifood Research Finland, Jokioinen FIN-31600, Finland.
Curr Opin Virol. 2013 Dec;3(6):604-14. doi: 10.1016/j.coviro.2013.08.009. Epub 2013 Sep 12.
Retrotransposons comprise the bulk of large plant genomes, replicating via an RNA intermediate whereby the original, integrated element remains in place. Of the two main orders, the LTR retrotransposons considerably outnumber the LINEs. LINEs integrate into target sites simultaneously with the RNA transcript being copied into cDNA by target-primed reverse transcription. LTR retrotransposon replication is basically equivalent to the intracellular phase of retroviral life cycles. The envelope gene giving extracellular mobility to retroviruses is in fact widespread in plants and their retrotransposons. Evolutionary analyses of the retrotransposons and retroviruses suggest that both form an ancient monophyletic group. The particular adaptations of LTR retrotransposons to plant life cycles enabling their success remain to be clarified.
逆转录转座子构成了大型植物基因组的大部分，通过 RNA 中间体进行复制，其中原始的整合元件保持原位。在这两个主要的分类中，LTR 逆转录转座子的数量远远超过 LINEs。LINEs 与 RNA 转录本一起整合到靶标位点，通过靶标引物反转录将 RNA 转录本复制成 cDNA。LTR 逆转录转座子的复制基本上相当于逆转录病毒生命周期的细胞内阶段。赋予逆转录病毒细胞外迁移能力的包膜基因实际上在植物及其逆转录转座子中广泛存在。对逆转录转座子和逆转录病毒的进化分析表明，它们形成了一个古老的单系群。LTR 逆转录转座子适应植物生命周期的特殊适应性，使其取得成功，这仍有待阐明。
