The complete nucleotide sequence of the hornwort (Anthoceros formosae) chloroplast genome:: insight into the earliest land plants
The complete nucleotide sequence of the hornwort (Anthoceros formosae) chloroplast genome:: insight into the earliest land plants
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DOI：
10.1093/nar/gkg155
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发表时间：
2003-01-15
影响因子：
14.9
通讯作者：
Yoshinaga, K
中科院分区：
文献类型：
--
作者：
Kugita, M;Kaneko, A;Yoshinaga, K
一般认为苔藓植物是最早的陆地植物。然而，苔藓、苔类和角苔等苔藓植物之间的系统发育关系尚不清楚。为了获得更多关于最早陆地植物的信息，我们测定了角蒿（Anthoceros formosae）叶绿体基因组的完整核苷酸序列。16162bp的环状双链DNA是迄今为止报道的陆地植物叶绿体中最大的基因组。它含有76个蛋白质，32个tRNA和4个rRNA基因和10个开放阅读框（orf），与分析的其他绿色植物的叶绿体基因组相同。主要的区别是与地茅相比有更大的反向重复，Anthoceros含有过量的ndhB和rps7基因以及rps12的3'外显子。陆生植物叶绿体基因组中常见的基因matK和rps15是假基因。rn23内含子是陆地植物叶绿体基因组中首次发现的内含子。角苔叶绿体的一个显著特征是，超过一半的蛋白质编码基因具有无义密码子，这些无义密码子通过RNA编辑转化为有义密码子。基于绿色植物叶绿体基因组中编码的52种蛋白质的11518个氨基酸位点的最大似然（ML）分析，将苔类列为所有其他陆地植物的姐妹植物。
It is generally believed that bryophytes are the earliest land plants. However, the phylogenetic relationships among bryophytes, including mosses, liverworts and hornworts, are not clearly resolved. To obtain more information on the earliest land plants, we determined the complete nucleotide sequence of the chloroplast genome from the hornwort Anthoceros formosae. The circular double-stranded DNA of 161 162 bp is the largest genome ever reported among land plant chloroplasts. It contains 76 protein, 32 tRNA and 4 rRNA genes and 10 open reading frames (ORFs), which are identical with the chloroplast genome of the other green plants analyzed. The major difference is a larger inverted repeat than that of the liverwort Marchantia, Anthoceros contains an excess of ndhB and rps7 genes and the 3' exon of rps12. The genes matK and rps15, commonly found in the chloroplast genomes of land plants, are pseudogenes. The intron of rrn23 is the first finding in the known chloroplast genomes of land plants. A striking feature of the hornwort chloroplast is that more than half of the protein-coding genes have nonsense codons, which are converted into sense codons by RNA editing. Maximum-likelihood (ML) analysis, based on 11 518 amino acid sites of 52 proteins encoded in the chloroplast genomes of the green plants, placed liverworts as the sister to all other land plants.