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Comparative and phylogenetic analysis of the complete chloroplast genomes of Osmanthus (Oleaceae) species
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  • Jiangpeng Dai,
  • Qiaozhen Liu,
  • Zhijie Tan,
  • Yiming Cai,
  • Xiaoxia Gao,
  • Shuang Zhu
Jiangpeng Dai
Guangdong Pharmaceutical University
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Qiaozhen Liu
Guangdong Pharmaceutical University
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Zhijie Tan
Guangdong Pharmaceutical University
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Yiming Cai
Guangdong Pharmaceutical University
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Xiaoxia Gao
Guangdong Pharmaceutical University
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Shuang Zhu
Guangdong Pharmaceutical University

Corresponding Author:[email protected]

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Abstract

As one genus of Oleaceae, Osmanthus is well-known for its high ornamental value. Due to the deficiency of clearly discriminatory traits, the species classification of genus Osmanthus is controversial. Here, we obtained two chloroplast genomes of O. fragrans and O. matsumuranus using Illumina sequencing, and compared them with 13 previously published chloroplast genomes of Osmanthus species. The chloroplast genomes of 15 Osmanthus species were 155,155 to 155,570 bp in length, which showed a typical quadripartite structure with high conservation of gene order and gene content. Each chloroplast genome had 132 genes including 87 protein-coding genes, 37 tRNA genes and eight rRNA genes. The number of simple sequence repeats identified in each Osmanthus species was in the range of 55-68. A total of 11 highly variable loci could be potentially used as specific molecular markers in the identification of Osmanthus species. The third position of codons tended to use A/U base, and natural selection contributed more in the formation of codon usage bias in comparison to mutation pressure. The chloroplast genome phylogenetic analysis showed that the species of Sect. Leiolea formed a well-supported monophyletic clade sister to Chionanthus virginicus. Besides, O. austrocaledonicus also separated as a distinct lineage nested within the members of Notelaea and Nestegis. The results of comparative and phylogenetic analysis provide valuable references for further study in identification, breeding improvement and phylogenetic relationships in Osmanthus species.