The subfamily Pothoideae belongs to the ecologically important plant family Araceae. Here, we report the chloroplast genomes of two species of the subfamily Pothoideae: Anthurium huixtlense (size: 163,116 bp) and Pothos scandens (size: 164,719 bp). The chloroplast genome of P. scandens showed unique contraction and expansion of inverted repeats (IRs), thereby increasing the size of the large single-copy region (LSC: 102,956 bp) and decreasing the size of the small single-copy region (SSC: 6779 bp). This led to duplication of many single-copy genes due to transfer to IR regions from the small single-copy (SSC) region, whereas some duplicate genes became single copy due to transfer to large single-copy regions. The rate of evolution of protein-coding genes was affected by the contraction and expansion of IRs; we found higher mutation rates for genes that exist in single-copy regions as compared to those in IRs. We found a 2.3-fold increase of oligonucleotide repeats in P. scandens when compared with A. huixtlense, whereas amino acid frequency and codon usage revealed similarities. The ratio of transition to transversion mutations was 2.26 in P. scandens and 2.12 in A. huixtlense. Transversion mutations mostly translated in non-synonymous substitutions. The phylogenetic inference of the limited species showed the monophyly of the Araceae subfamilies. Our study provides insight into the molecular evolution of chloroplast genomes in the subfamily Pothoideae and family Araceae.

tho科亚科属于重要的植物科天南星科。在这里，我们报告两个亚科Pothoideae的叶绿体基因组：Anthurium huixtlense（大小：163,116 bp）和Pothos scandens（大小：164,719 bp）。绿假单胞菌的叶绿体基因组反向重复序列（IRs）的独特收缩和扩增，从而增加了大单拷贝区域的大小（LSC：102,956 bp），并减小了小单拷贝区域的大小（SSC：6779 bp）。由于从小单拷贝（SSC）区域转移到IR区域，导致许多单拷贝基因重复，而一些重复的基因由于转移到大单拷贝区域而变成单拷贝。蛋白质编码基因的进化速度受IRs的收缩和扩展的影响。我们发现与IR相比，存在于单拷贝区域的基因的突变率更高。与A. huixtlense相比，我们发现P. scandens中的寡核苷酸重复序列增加了2.3倍，而氨基酸频率和密码子用法显示出相似性。P. scandens的转化与颠换突变的比率为2.26 ，A. huixtlense的为2.12 。颠换突变大多翻译成非同义替换。有限物种的系统发育推断显示天南星科的亚科。我们的研究提供了洞悉亚科Pothoideae和科Araceae中叶绿体基因组分子进化的见识。