Abstract: To investigate the comprehensive characteristics of the chloroplast genome of Sesuvium portulacastrum （L.）L.， a mangrove companion plant， the chloroplast DNA of S. portulacastrum was sequenced and analyzed using high-throughput sequencing technology. The results showed that the total length of the chloroplast genome was 155 932 bp， with a GC content of 36.50%. 133 coding genes were annotated， including 75 protein-coding genes encoded by 22 945 codons， predominantly terminating in A/U. This genome exhibits a typical tetrad structure and demonstrates a high degree of conservation with S. sesuvioides， sharing 129 genes in virtually identical sequences. Additionally， 75 SSR sites were detected， with a predominant 77.33% located in the large single copy region （LSC）. Notably， single nucleotide repeats accounted for 92.00%. Based on 48 common protein-coding genes of 10 species including S. portulacastrum were constructed a phylogenetic tree using the Maximum Likelihood （ML） method. Phylogenetic analysis further underscores the close genetic proximith between S. portulacastrum and S. sesuvioides. Furthermore， the psbB gene in S. portulacastrum possesses an open reading frame of 1527 bp. When it was overexpressed in Arabidopsis thaliana （L.） Heynh.， this gene leads to a substantial increase in chlorophyll content. This study not only deepens our understanding of the chloroplast genome of S. portulacastrum but also provides invaluable insights for molecular-assisted breeding of S. portulacastrum.

Key words: Sesuvium portulacastrum L., Chloroplast genome, SSR, Phylogenetic analysis, psbB gene, Gene function

摘要： 为探究红树林伴生植物海马齿（Sesuvium portulacastrum （L.） L.）叶绿体基因组的综合特征，本研究通过高通量测序技术对其叶绿体DNA进行测序。结果表明：海马齿叶绿体基因组全长155 932 bp，GC含量36.50%，注释得到133个编码基因，其中蛋白编码基因75个，密码子22 945个，偏好以A/U结尾。该叶绿体基因组呈典型四分体结构，与Sesuvium sesuvioides （Fenzl） Verdc.高度保守，共享基因达129个且排列顺序相同。共检测到75个SSR位点，其中约77.33%分布在大单拷贝区（LSC），单核苷酸重复序列出现频率高达92.00%。基于10个物种（含海马齿）的48个共有蛋白编码基因通过最大似然法构建系统发育树，分析结果表明海马齿与S. sesuvioides的亲缘关系最近。海马齿叶绿体psbB基因开放阅读框长1527 bp，其在拟南芥（Arabidopsis thaliana （L.） Heynh.）中过表达可显著提升叶绿素含量。本研究有助于充分了解海马齿叶绿体基因组结构和功能，为进一步进行海马齿分子辅助育种提供参考。

关键词: 海马齿, 叶绿体基因组, SSR, 系统发育分析, psbB基因, 基因功能