Gene transfer to the nucleus and the evolution of chloroplasts
Gene transfer to the nucleus and the evolution of chloroplasts
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DOI：
10.1038/30234
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发表时间：
1998-05-14
期刊：
影响因子：
64.8
通讯作者：
Kowallik, KV
中科院分区：
文献类型：
--
作者：
Martin, W;Stoebe, B;Kowallik, KV
光合真核生物，特别是单细胞生物，拥有的化石记录要么存在间隙，要么难以解释，或者两者兼而有之。重建其进化的尝试集中在质体系统发育上，但受到单个基因中包含的系统发育信息的数量和类型的限制(1-5)。在来自青藻、红藻、硅藻、裸藻和五种陆地植物的叶绿体基因组中包含的 210 个不同的蛋白质编码基因已完全测序，我们现在已经鉴定出每种基因组和蓝藻外群基因组共有的 45 个基因组。通过对每个基因组 11,039 个氨基酸位置进行比对进行的系统发育推断表明，这些信息足以（但仅勉强如此）来识别有根的九分类单元拓扑。我们绘制了整个推断树中叶绿体基因组基因丢失的过程，并发现，令人惊讶的是，多个谱系中独立的平行基因丢失数量比系统发育上独特的丢失数量多出 4:1。我们鉴定出 44 种不同质体编码蛋白的同源物作为叶绿体起源的功能性核基因，为植物中内共生基因转移到细胞核提供了证据。
Photosynthetic eukaryotes, particularly unicellular forms, possess a fossil record that is either wrought with gaps or difficult to interpret, or both. Attempts to reconstruct their evolution have focused on plastid phylogeny, but were limited by the amount and type of phylogenetic information contained within single genes(1-5). Among the 210 different protein-coding genes contained in the completely sequenced chloroplast genomes from a glaucocystophyte, a rhodophyte, a diatom, a euglenophyte and five land plants, we have now identified the set of 45 common to each and to a cyanobacterial outgroup genome. Phylogenetic inference with an alignment of 11,039 amino-acid positions per genome indicates that this information is sufficient - but just barely so - to identify the rooted nine-taxon topology. We mapped the process of gene loss from chloroplast genomes across the inferred tree and found that, surprisingly, independent parallel gene losses in multiple lineages outnumber phylogenetically unique losses by more than 4:1. We identified homologues of 44 different plastid-encoded proteins as functional nuclear genes of chloroplast origin, providing evidence for endosymbiotic gene transfer to the nucleus in plants.