Complete chloroplast genome features and phylogenetic analysis of Eruca sativa (Brassicaceae).

Eruca sativa Mill. (Brassicaceae) is an important edible vegetable and a potential medicinal plant due to the antibacterial activity of its seed oil. Here, the complete chloroplast (cp) genome of E. sativa was de novo assembled with a combination of long PacBio reads and short Illumina reads. The E. sativa cp genome had a quadripartite structure that was 153,522 bp in size, consisting of one large single-copy region of 83,320 bp and one small single-copy region of 17,786 bp which were separated by two inverted repeat (IRa and IRb) regions of 26,208 bp. This complete cp genome harbored 113 unique genes: 79 protein-coding genes, 30 tRNA genes, and four rRNA genes. Forty-nine long repetitive sequences and 69 simple sequence repeats were identified in the E. sativa cp genome. A codon usage analysis of the E. sativa cp genome showed a bias toward codons ending in A/T. The E. sativa cp genome was similar in size, gene composition, and linearity of the structural region when compared with other Brassicaceae cp genomes. Moreover, the analysis of the synonymous (Ks) and non-synonymous (Ka) substitution rates demonstrated that protein-coding genes generally underwent purifying selection pressure, expect ycf1, ycf2, and rps12. A phylogenetic analysis determined that E. sativa is evolutionarily close to important Brassica species, indicating that it may be possible to transfer favorable E. sativa alleles into other Brassica species. Our results will be helpful to advance genetic improvement and breeding of E. sativa, and will provide valuable information for utilizing E. sativa as an important resource to improve other Brassica species.

Chloroplast genome features of an important medicinal and edible plant: Houttuynia cordata (Saururaceae).

Houttuynia cordata (Saururaceae), an ancient and relic species, has been used as an important medicinal and edible plant in most parts of Asia. However, because of the lack of genome information and reliable molecular markers, studies on its population structure, or phylogenetic relationships with other related species are still rare. Here, we de novo assembled the complete chloroplast (cp) genome of H. cordata using the integration of the long PacBio and short Illumina reads. The cp genome of H. cordata showed a typical quadripartite cycle of 160,226 bp. This included a pair of inverted repeats (IRa and IRb) of 26,853 bp, separated by a large single-copy (LSC) region of 88,180 bp and a small single-copy (SSC) region of 18,340 bp. A total of 112 unique genes, including 79 protein-coding genes, 29 tRNA genes, and four rRNA genes, were identified in this cp genome. Eighty-one genes were located on the LSC region, 13 genes were located on the SSC region, and 17 two-copy genes were located on the IR region. Additionally, 48 repeat sequences and 86 SSR loci, which can be used as genomic markers for population structure analysis, were also detected. Phylogenetic analysis using 21 cp genomes of the Piperales family demonstrated that H. cordata had a close relationship with the species within the Aristolochia genus. Moreover, the results of mVISTA analysis and comparisons of IR regions demonstrated that the cp genome of H. cordata was conserved with that of the Aristolochia species. Our results provide valuable information for analyzing the genetic diversity and population structure of H. cordata, which can contribute to further its genetic improvement and breeding.

The complete chloroplast genome sequence of garden cress (Lepidium sativum L.) and its phylogenetic analysis in Brassicaceae family.

Garden cress, Lepidium sativum L., is not only an important vegetable which is cultivated in the entire world, but also a widely used folk medicine for the treatment of hyperactive airways disorders. However, as a member of Brassicaceae, few studies have been carried out on its phylogenetic relationship with other Brassicaceae members. Herein, the complete chloroplast (cp) genome of garden cress wa deciphered by the combination of Illumina Hiseq and PacBio Hiseq Platform after extracting of its cp DNA. The cp genome showed a typically quadripartite cycle with 154997 bp, including a pair of inverted repeats (IRa and IRb) of 26491 bp intersected by a large single copy (LSC) region of 84007 bp and a small single copy (SSC) region of 18008 bp. Totally, 128 unique genes were assembled in this cp genome, including 83 protein genes, 37 tRNAs and 8 rRNAs. A total of 73 simple sequence repeats (SSRs) with a length of at least 10 bp were detected. Phylogenetic analysis based on 30 cp genome of Brassicaceae family showed that the L. sativum was closely related to L. virginicum. This study provides important information for future evolution, genetic and molecular biology studies of L. sativum.