Sequencing and Analysis of Schousb and The Complete Chloroplast Genomes Reveal Two Inversions and as Barcoding of the Vegetable.

Schousb and are widely distributed edible vegetables and the sources of the Chinese medicine . The complete chloroplast (cp) genome of usually occurs in the inversions of two regions. Hence, the cp genome sequences and structures of species are crucial for the cp genome genetic diversity and evolutionary studies. Hence, in this paper, we have sequenced and analyzed for the first time the cp genome size of Schousb and , which are 149,752 bp and 152,885 bp, with a pair of inverted repeats (IRs) (24,523 bp and 25,003) separated by a large single copy (LSC) region (82,290 bp and 84,610) and a small single copy (SSC) region (18,416 bp and 18,269), respectively. In total, 79 protein-coding genes, 30 distinct transfer RNA (tRNA) genes, four distinct rRNA genes and two pseudogenes were found not only in Schousb but also in the cp genome. Fifty-two (52) and fifty-nine (59) repeats, and seventy (70) and ninety (90) simple sequence repeats (SSRs) were found in the Schousb and cp genomes, respectively. Codon usage analysis showed that leucine, isoleucine, and serine are the most frequent amino acids and that the UAA stop codon was the significantly favorite stop codon in both cp genomes. The two inversions, the LSC region ranging from to and the whole SSC region were found in both of them. The complete cp genome comparison with other species showed that the coding area is more conservative than the non-coding area. The phylogenetic analysis revealed that the gene is a good barcoding marker for identifying different vegetables. These results give an insight into the identification, the barcoding, and the understanding of the evolutionary model of the cp genome.