The Chloroplast Genome of Symplocarpus renifolius: A Comparison of Chloroplast Genome Structure in Araceae

Abstract

<i>Symplocarpus renifolius</i> is a member of Araceae family that is extraordinarily diverse in appearance. Previous studies on chloroplast genomes in Araceae were focused on duckweeds (Lemnoideae) and root crops (<i>Colocasia</i>, commonly known as taro). Here, we determined the chloroplast genome of <i>Symplocarpus renifolius</i> and compared the factors, such as genes and inverted repeat (IR) junctions and performed phylogenetic analysis using other Araceae species. The chloroplast genome of <i>S. renifolius</i> is 158,521 bp and includes 113 genes. A comparison among the Araceae chloroplast genomes showed that <i>infA</i> in <i>Lemna</i>, <i>Spirodela</i>, <i>Wolffiella</i>, <i>Wolffia</i>, <i>Dieffenbachia</i> and <i>Colocasia</i> has been lost or has become a pseudogene and has only been retained in <i>Symplocarpus</i>. In the Araceae chloroplast DNA (cpDNA), <i>psbZ</i> is retained. However, <i>psbZ</i> duplication occurred in <i>Wolffia</i> species and tandem repeats were noted around the duplication regions. A comparison of the IR junction in Araceae species revealed the presence of <i>ycf1</i> and <i>rps15</i> in the small single copy region, whereas duckweed species contained <i>ycf1</i> and <i>rps15</i> in the IR region. The phylogenetic analyses of the chloroplast genomes revealed that <i>Symplocarpus</i> are a basal group and are sister to the other Araceae species. Consequently, <i>infA</i> deletion or pseudogene events in Araceae occurred after the divergence of <i>Symplocarpus</i> and aquatic plants (duckweeds) in Araceae and duplication events of <i>rps15</i> and <i>ycf1</i> occurred in the IR region.