Chloroplast Genome of the Folk Medicine and Vegetable Plant Talinum paniculatum (Jacq.) Gaertn.: Gene Organization, Comparative and Phylogenetic Analysis

The complete chloroplast (cp) genome of Talinum paniculatum (Caryophyllale), a source of pharmaceutical efficacy similar to ginseng, and a widely distributed and planted edible vegetable, were sequenced and analyzed. The cp genome size of T. paniculatum is 156,929 bp, with a pair of inverted repeats (IRs) of 25,751 bp separated by a large single copy (LSC) region of 86,898 bp and a small single copy (SSC) region of 18,529 bp. The genome contains 83 protein-coding genes, 37 transfer RNA (tRNA) genes, eight ribosomal RNA (rRNA) genes and four pseudogenes. Fifty one (51) repeat units and ninety two (92) simple sequence repeats (SSRs) were found in the genome. The pseudogene rpl23 (Ribosomal protein L23) was insert AATT than other Caryophyllale species by sequence alignment, which located in IRs region. The gene of trnK-UUU (tRNA-Lys) and rpl16 (Ribosomal protein L16) have larger introns in T. paniculatum, and the existence of matK (maturase K) genes, which usually located in the introns of trnK-UUU, rich sequence divergence in Caryophyllale. Complete cp genome comparison with other eight Caryophyllales species indicated that the differences between T. paniculatum and P. oleracea were very slight, and the most highly divergent regions occurred in intergenic spacers. Comparisons of IR boundaries among nine Caryophyllales species showed that T. paniculatum have larger IRs region and the contraction is relatively slight. The phylogenetic analysis among 35 Caryophyllales species and two outgroup species revealed that T. paniculatum and P. oleracea do not belong to the same family. All these results give good opportunities for future identification, barcoding of Talinum species, understanding the evolutionary mode of Caryophyllale cp genome and molecular breeding of T. paniculatum with high pharmaceutical efficacy.