Assembly and comparative analysis of the complete mitochondrial and chloroplast genome of Cyperus stoloniferus (Cyperaceae), a coastal plant possessing saline-alkali tolerance.

BACKGROUND: Cyperus stoloniferus is an important species in coastal ecosystems and possesses economic and ecological value. To elucidate the structural characteristics, variation, and evolution of the organelle genome of C. stoloniferus, we sequenced, assembled, and compared its mitochondrial and chloroplast genomes. RESULTS: We assembled the mitochondrial and chloroplast genomes of C. stoloniferus. The total length of the mitochondrial genome (mtDNA) was 927,413 bp, with a GC content of 40.59%. It consists of two circular DNAs, including 37 protein-coding genes (PCGs), 22 tRNAs, and five rRNAs. The length of the chloroplast genome (cpDNA) was 186,204 bp, containing 93 PCGs, 40 tRNAs, and 8 rRNAs. The mtDNA and cpDNA contained 81 and 129 tandem repeats, respectively, and 346 and 1,170 dispersed repeats, respectively, both of which have 270 simple sequence repeats. The third high-frequency codon (RSCU > 1) in the organellar genome tended to end at A or U, whereas the low-frequency codon (RSCU < 1) tended to end at G or C. The RNA editing sites of the PCGs were relatively few, with only 9 and 23 sites in the mtDNA and cpDNA, respectively. A total of 28 mitochondrial plastid DNAs (MTPTs) in the mtDNA were derived from cpDNA, including three complete trnT-GGU, trnH-GUG, and trnS-GCU. Phylogeny and collinearity indicated that the relationship between C. stoloniferus and C. rotundus are closest. The mitochondrial rns gene exhibited the greatest nucleotide variability, whereas the chloroplast gene with the greatest nucleotide variability was infA. Most PCGs in the organellar genome are negatively selected and highly evolutionarily conserved. Only six mitochondrial genes and two chloroplast genes exhibited Ka/Ks > 1; in particular, atp9, atp6, and rps7 may have undergone potential positive selection. CONCLUSION: We assembled and validated the mtDNA of C. stoloniferus, which contains a 15,034 bp reverse complementary sequence. The organelle genome sequence of C. stoloniferus provides valuable genomic resources for species identification, evolution, and comparative genomic research in Cyperaceae.

The complete chloroplast genome of highbush blueberry (Vaccinium corymbosum).

Highbush blueberry is a small berry fruit tree belonging to the family Ericaceae and genus Vaccinium, which fruit has high nutritional value. High-throughput sequencing technology was applied in this study to sequence and assemble the whole chloroplast genome of the southern highbush blueberry variety sharpblue. The results of the study showed that the circular genome of sharpblue is 170,737 bp in length, and the GC content of the genome was 36.8%. The complete chloroplast genome of sharpblue has consisted of two inverted repeat regions (IRs), a large single-copy region (LSC, 31, 076 bp), and a small single-copy region (SSC, 3, 044 bp). The chloroplast genome contained a total of 144 functional genes, including 100 mRNA genes, eight rRNA genes, and 36 tRNA genes. In addition, V. corymbosum and V. oldhamii were clustered into one group in this phylogenetic analysis which indicated that they have a close evolutionary relationship. The findings of this investigation are a significant reference source for the phylogeny and evolutionary origin of the Ericaceae family.

Complete chloroplast genome sequence of Pueraria thomsonii, an important traditional Chinese medicine plant.

Pueraria thomsonii is a leguminous plant with high root yield and starch content. It is also a medicinal material in the Chinese pharmacopeia. However, the raw materials of P. thomsonii are often confused with some non-medicinal Pueraria plants. To enrich the genetic resources of P. thomsonii and guide its molecular identification, the complete chloroplast genome was sequenced and reported. The total genome of P. thomsonii is 153,434 bp in length. consisting of two inverted repeat regions (IRS, 25,640 bp each) separated by a large single-copy (LSC, 84,155 bp) and a small single-copy region (SSC, 17,999 bp). The overall GC content is 35.41%. It contains 130 genes, including 85 protein coding genes, 8 rRNA genes and 37 tRNA genes. Phylogenetic analysis showed that P. thomsonii could be distinguished from other plants and closely related to the legume Pachyrhizus erosus. This study enriches the genetic information of P. thomsonii and contributes to the screening of excellent germplasm.