Complete Chloroplast Genome Analysis of Two Important Medicinal Alpinia Species: Alpinia galanga and Alpinia kwangsiensis

Genetic characterization and phylogenetic analysis of the Nigella sativa (black seed) plastome

In this study, the complete plastome sequence of Nigella sativa (black seed), was analyzed for the first time. The plastome spans approximately 154,120 bp, comprising four sections: the Large Single-Copy (LSC) (85,538 bp), the Small Single-Copy (SSC) (17,984 bp), and two Inverted Repeat (IR) regions (25,299 bp). A comparative study of N. sativa's plastome with ten other species from various genera in the Ranunculaceae family reveals substantial structural variations. The contraction of the inverted repeat region in N. sativa influences the boundaries of single-copy regions, resulting in a shorter plastome size than other species. When comparing the plastome of N. sativa with those of its related species, significant divergence is observed, particularly except for N. damascena. Among these, the plastome of A. glaucifolium displays the highest average pairwise sequence divergence (0.2851) with N. sativa, followed by A. raddeana (0.2290) and A. coerulea (0.1222). Furthermore, the study identified 12 distinct hotspot regions characterized by elevated Pi values (> 0.1). These regions include trnH-GUG-psbA, matK-trnQ-UUG, psbK-trnR-UCU, atpF-atpI, rpoB-psbD, ycf3-ndhJ, ndhC-cemA, petA-psaJ, trnN-GUU-ndhF, trnV-GAC-rps12, ycf2-trnI-CAU, and ndhA-ycf1. Approximately, 24 tandem and 48 palindromic and forward repeats were detected in N. sativa plastome. The analysis revealed 32 microsatellites with the majority being mononucleotide repeats. In the N. sativa plastome, phenylalanine had the highest number of codons (1982 codons), while alanine was the least common amino acid with 260 codons. A phylogenetic tree, constructed using protein-coding genes, revealed a distinct monophyletic clade comprising N. sativa and N. damascene, closely aligned with the Cimicifugeae tribe and exhibiting robust support. This plastome provides valuable genetic information for precise species identification, phylogenetic resolution, and evolutionary studies of N. sativa.

The complete chloroplast genome of Hedychium flavum Roxb., an ornamental, edible and medicinal plant

Hedychium flavum Roxb. 1820 is a perennial herb mainly distributed in China, India, Myanmar and Thailand with ornamental, edible and medicinal value. It is extensively cultivated as a source of aromatic essential oils, ornamental plant, food flavorings and vegetables, and folk medicine. In this study, we sequence the complete chloroplast genome of H. flavum by de novo assembly. The assembled genome has a typical quadripartite circular structure with 163,909 bp in length, containing a large single-copy region (LSC, 88,589 bp), a small single-copy region (SSC, 15,762 bp), and two inverted repeat regions (IRs, 29,779 bp). The cp genome contains 133 genes, including 87 protein-coding genes, 38 tRNA genes and 8 rRNA genes. Phylogenetic analysis based on the complete cp genome shows a close affinity of H. flavum and H. neocarneum with 100% bootstrap support. This study will provide useful genetic resource for further phylogenetic analysis of the genus Hedychium and Zingiberaceae.

Comparison of Biological and Genetic Characteristics between Two Most Common Broad-Leaved Weeds in Paddy Fields: Ammannia arenaria and A. multiflora (Lythraceae)

Ammannia arenaria and A. multifloras, morphologically similar at the seedling stage, are the most common broad-leaved weeds in paddy fields. Our study showed that A. arenaria occupied more space than A. multifloras when competing with rice. However, A. multifloras germination has lower temperature adaptability. No difference in sensitivity to common herbicides between two Ammannia species was observed. Chloroplast (cp) genomes could be conducive to clarify their genetic relationship. The complete cp genome sequences of A. arenaria (158,401 bp) and A. multiflora (157,900 bp) were assembled for the first time. In A. arenaria, there were 91 simple sequence repeats, 115 long repeats, and 86 protein-encoding genes, one, sixteen, and thirty more than those in A. multiflora. Inverted repeats regions expansion and contraction and the phylogenetic tree based on cp genomes demonstrated the closely relationship between the two species. However, in A. arenaria, 20 single nucleotide polymorphisms in the CDS region were detected compared to A. multiflora, which can be used to distinguish the two species. Moreover, there was one unique gene, infA, only in A. arenaria. This study provides reliable molecular resources for future research focusing on the infrageneric taxa identification, phylogenetic resolution, population structure, and biodiversity of Ammannia species.

Complete chloroplast genome sequences of the medicinal plant Aconitum transsectum (Ranunculaceae): comparative analysis and phylogenetic relationships

BACKGROUND

Aconitum transsectum Diels. (Ranunculaceae) is an important medicinal plant that is widely used in traditional Chinese medicine, but its morphological traits make it difficult to recognize from other Aconitum species. No research has sequenced the chloroplast genome of A.transsectum, despite the fact that phylogenetic analysis based on chloroplast genome sequences provides essential evidence for plant classification.

RESULTS

In this study, the chloroplast (cp) genome of A. transsectum was sequenced, assembled, and annotated. A. transsectum cp genome is a 155,872 bp tetrameric structure including a large single copy (LSC, 87,671 bp) and a small single copy (SSC, 18,891 bp) section, as well as a pair of inverted repeat sequences (IRa and IRb, 25,894 bp each). 131 genes are encoded by the complete cp genome, comprising 86 protein-coding genes, 37 tRNAs, and 8 rRNAs. The most favored codon in the A. transsectum cp genome is AUG, and 46 repeats and 241 SSRs were also identified. The A. transsectum cp genome is similar in size, gene composition, and IR expansion and contraction to the cp genomes of seven Ranunculaceae species. Phylogenetic analysis of cp genomes of 28 plants from the Ranunculaceae family shows that A. transsectum is most closely related to A. vilmorinianum, A. episcopale, and A. forrestii of Subgen. Aconitum.

CONCLUSIONS

Overall, this study provides complete cp genome resources for A. transsectum that will be beneficial for identifying potential.

Application of chloroplast genome in the identification of Phyllanthus urinaria and its common adulterants

BACKGROUND

Phyllanthus urinaria L. is extensively used as ethnopharmacological material in China. In the local marketplace, this medicine can be accidentally contaminated, deliberately substituted, or mixed with other related species. The contaminants in herbal products are a threat to consumer safety. Due to the scarcity of genetic information on Phyllanthus plants, more molecular markers are needed to avoid misidentification.

METHODS

In this study, the complete chloroplast genome of nine species of the genus Phyllanthus was de novo assembled and characterized.

RESULTS

This study revealed that all of these species exhibited a conserved quadripartite structure, which includes a large single copy (LSC) region and small single copy (SSC) region, and two copies of inverted repeat regions (IRa and IRb), which separate the LSC and SSC regions. And the genome structure, codon usage, and repeat sequences were highly conserved and showed similarities among the nine species. Three highly variable regions (trnS-GCU-trnG-UCC, trnT-UGU-trnL-UAA, and petA-psbJ) might be helpful as potential molecular markers for identifying P. urinaria and its contaminants. In addition, the molecular clock analysis results showed that the divergence time of the genus Phyllanthus might occur at ~ 48.72 Ma.

CONCLUSION

This study provides valuable information for further species identification, evolution, and phylogenetic research of Phyllanthus.

Comparative Analysis of Whole Chloroplast Genomes of Three Common Species of Echinochloa (Gramineae) in Paddy Fields

Echinochloa crus-galli var. crus-galli, E. crus-galli var. zelayensis, and E. glabrescens, morphologically similar at the seedling stage, are the most pernicious barnyard grass species in paddy fields worldwide. Chloroplast (cp) genomes could be conducive to their identification. In this study, we assembled the complete cp genome sequences of Echinochloa crus-galli var. crus-galli (139,856 bp), E. crus-galli var. zelayensis (139,874 bp), and E. glabrescens (139,874 bp), which exhibited a typical circular tetramerous structure, large and small single-copy regions, and a pair of inverted repeats. In Echinochloa crus-galli var. crus-galli, there were 136 simple sequence (SSRs) and 62 long (LRs) repeats, and in the other two species, 139 SSRs and 68 LRs. Each cp genome contains 92 protein-encoding genes. In Echinochloa crus-galli var. crus-galli and E. glabrescens, 321 and 1 single-nucleotide polymorphisms were detected compared to Echinochloa crus-galli var. zelayensis. IR expansion and contraction revealed small differences between the three species. The phylogenetic tree based on cp genomes demonstrated the phylogenetic relationship between ten barnyard grass species and other common Gramineae plants, showing new genetic relationships of the genus Echinochloa. This study provides valuable information on cp genomes, useful for identifying and classifying the genus Echinochloa and studying its phylogenetic relationships and evolution.

Comparative chloroplast genome analyses of Amomum: insights into evolutionary history and species identification

BACKGROUND

Species in genus Amomum always have important medicinal and economic values. Classification of Amomum using morphological characters has long been a challenge because they exhibit high similarity. The main goals of this study were to mine genetic markers from cp genomes for Amomum species identification and discover their evolutionary history through comparative analysis.

RESULTS

Three species Amomum villosum, Amomum maximum and Amomum longipetiolatum were sequenced and annotated for the complete chloroplast (cp) genomes, and the cp genomes of A. longipetiolatum and A. maximum were the first reported. Three cp genomes exhibited typical quadripartite structures with 163,269-163,591 bp in length. Each genome encodes 130 functional genes including 79 protein-coding, 26 tRNAs and 3 rRNAs genes. 113-152 SSRs and 99 long repeats were identified in the three cp genomes. By designing specific primers, we amplified the highly variable loci and the mined genetic marker ccsA exhibited a relatively high species identification resolution in Amomum. The nonsynonymous and synonymous substitution ratios (Ka/Ks) in Amomum and Alpinia showed that most genes were subjected to a purifying selection. Phylogenetic analysis revealed the evolutionary relationships of Amomum and Alpinia species and proved that Amomum is paraphyletic. In addition, the sequenced sample of A. villosum was found to be a hybrid, becoming the first report of natural hybridization of this genus. Meanwhile, the high-throughput sequencing-based ITS2 analysis was proved to be an efficient tool for interspecific hybrid identification and with the help of the chloroplast genome, the hybrid parents can be also be determined.

CONCLUSION

The comparative analysis and mined genetic markers of cp genomes were conducive to species identification and evolutionary relationships of Amomum.