Complete chloroplast genome of <i>Tetragonia tetragonioides</i>: Molecular phylogenetic relationships and evolution in Caryophyllales

<div><p>The chloroplast genome of <i>Tetragonia tetragonioides</i> (Aizoaceae; Caryophyllales) was sequenced to provide information for studies on phylogeny and evolution within Caryophyllales. The chloroplast genome of <i>Tetragonia tetragonioides</i> is 149,506 bp in length and includes a pair of inverted repeats (IRs) of 24,769 bp that separate a large single copy (LSC) region of 82,780 bp and a small single copy (SSC) region of 17,188 bp. Comparative analysis of the chloroplast genome showed that Caryphyllales species have lost many genes. In particular, the <i>rpl2</i> intron and <i>infA</i> gene were not found in <i>T</i>. <i>tetragonioides</i>, and core Caryophyllales lack the <i>rpl2</i> intron. Phylogenetic analyses were conducted using 55 genes in 16 complete chloroplast genomes. Caryophyllales was found to divide into two clades; core Caryophyllales and noncore Caryophyllales. The genus <i>Tetragonia</i> is closely related to <i>Mesembryanthemum</i>. Comparisons of the synonymous (Ks), nonsynonymous (Ka), and Ka/Ks substitution rates revealed that nonsynonymous substitution rates were lower than synonymous substitution rates and that Ka/Ks rates were less than 1. The findings of the present study suggest that most genes are a purified selection.</p>