The complete chloroplast DNA sequence of the green alga Nephroselmis olivacea:: Insights into the architecture of ancestral chloroplast genomes
The complete chloroplast DNA sequence of the green alga Nephroselmis olivacea:: Insights into the architecture of ancestral chloroplast genomes
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DOI：
10.1073/pnas.96.18.10248
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发表时间：
1999-08-31
影响因子：
11.1
通讯作者：
Lemieux, C
中科院分区：
文献类型：
--
作者：
Turmel, M;Otis, C;Lemieux, C
绿色植物似乎形成了两个姐妹的谱系：绿藻门，包括绿藻纲，绿藻纲，绿藻纲和绿藻纲；链藻门，包括绿藻纲和陆生植物。我们已经确定了绿藻类（prinophyceae）中包括最早分化的绿藻后代的Nephroselmis olivacea的完整叶绿体DNA （cpDNA）序列（200,799 bp），在该基因组中鉴定的127个基因是迄今为止完整测序的绿藻和陆生植物cpDNA中最大的基因库。在肾自丝基因中，2个基因（ycf81和ftsI，一种参与肽聚糖合成的基因）尚未在任何先前研究的cpDNA中被鉴定出来；5个基因[ftsW， rnE, ycf62, rnpB, trnS(cga)]仅在非绿藻的cpdna中发现；另外10个（ndh基因）仅在陆生植物cpdna中被发现。肾自丝和陆地植物的cpdna具有相同的四分体结构，其特征是存在一个大的rrna编码反向重复和两个不相等的单拷贝区域，并且在相应的基因组区域中具有非常相似的基因集。鉴于我们的系统发育分析将肾自体置于绿藻中，这些结构特征很可能存在于绿藻和链藻共同祖先的cpDNA中。叶绿体基因组的比较分析表明，陆生植物cpdna典型的四方结构和基因分配模式是古老的特征，可能来源于叶绿体的蓝藻祖先基因组。我们的系统发育数据也提供了深入了解裸藻叶绿体的绿藻祖先。
Green plants seem to form two sister lineages: Chlorophyta, comprising the green algal classes Prasinophyceae, Ulvophyceae, Trebouxiophyceae, and Chlorophyceae, and Streptophyta, comprising the Charophyceae and land plants. We have determined the complete chloroplast DNA (cpDNA) sequence (200,799 bp) of Nephroselmis olivacea, a member of the class (Prasinophyceae) thought to include descendants of the earliest-diverging green algae, The 127 genes identified in this genome represent the largest gene repertoire among the green algal and land plant cpDNAs completely sequenced to date. Of the Nephroselmis genes, 2 (ycf81 and ftsI, a gene involved in peptidoglycan synthesis) have not been identified in any previously investigated cpDNA; 5 genes [ftsW, rnE, ycf62, rnpB, and trnS(cga)] have been found only in cpDNAs of nongreen algae; and 10 others (ndh genes) have been described only in land plant cpDNAs. Nephroselmis and land plant cpDNAs share the same quadripartite structure-which is characterized by the presence of a large rRNA-encoding inverted repeat and two unequal single-copy regions-and very similar sets of genes in corresponding genomic regions. Given that our phylogenetic analyses place Nephroselmis within the Chlorophyta, these structural characteristics were most likely present in the cpDNA of the common ancestor of chlorophytes and streptophytes. Comparative analyses of chloroplast genomes indicate that the typical quadripartite architecture and gene-partitioning pattern of land plant cpDNAs are ancient features that may have been derived from the genome of the cyanobacterial progenitor of chloroplasts. Our phylogenetic data also offer insight into the chlorophyte ancestor of euglenophyte chloroplasts.