Characteristics and comparative analysis of Mesona chinensis Benth chloroplast genome reveals DNA barcode regions for species identification

Preparation technologies, structural features, and biological activities of polysaccharides from Mesona chinensis Benth.: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Mesona chinensis Benth. (or Platostoma palustre (Blume) A. J. Paton) is an important medicinal and edible plant also known as the Hsian-tsao in China and Southeast Asian countries. It is cold in nature and sweet in taste, with the effects of clearing heat, relieving heatstroke and diuretic, and traditionally used to treat heatstroke, erysipelas, hypertension, joint pain and other diseases in folk medicine. It is also a popular supplement with the function of detoxifying and heat-clearing use in Asia. It is used to be processed into the popular tea, Bean jelly, and so on. Published studies have demonstrated that polysaccharides from M. chinensis (MCPs) are one of the principal bioactive ingredients with a variety of health-promoting effects in the prevention and treatment of diseases, including antioxidant, immunomodulation, anti-inflammatory, hepatoprotective, anti-tumor, hypoglycemic, regulation of gut microbiota, and other pharmacological properties.

AIM OF THE REVIEW

This review aims to compile the extraction and purification methods, structural characteristics, pharmacological activities including the mechanism of action of MCPs, and to further understand the applications of M. chinensis in order to lay the foundation for the development of MCPs.

MATERIALS AND METHODS

By inputting the search term "Mesona chinensis polysaccharides", relevant research information was obtained from databases such as PubMed, Google Scholar, Web of Science, and China National Knowledge Infrastructure (CNKI).

RESULTS

More than 40 polysaccharides have been extracted from M. chinensis, different extraction and purification methods have been described, as well as the structural features and pharmacological activities of MCPs have been systematically reviewed. Polysaccharides, as important components of M. chinensis, were mainly extracted by methods such as hot water dipping method, hot alkali extraction method, enzyme-assisted extraction method and ultrasonic-assisted extraction method, subsequently obtained by decolorization, deproteinization, removal of other small molecules and separation on various chromatographic columns. The chemical composition and structure of MCPs show diversity and have a variety of pharmacological activities, including antioxidant, immunomodulation, anti-inflammatory, hepatoprotective, anti-tumor, hypoglycemic, regulation of gut microbiota, and so on.

CONCLUSIONS

This article systematically reviews the research progress of MCPs in terms of extraction and purification, structural characteristics, rheological gel properties, pharmacological properties, and safety assessment. The potentials and roles of M. chinensis in the field of medicine, functional food, and materials are further highlighted to provide references and bases for the high-value processing and utilization of MCPs.

Effects of different colors of plastic-film mulching on soil temperature, yield, and metabolites in Platostoma palustre

Platostoma palustre is an annual herb and an important medicinal and edible plant in southern China. Plastic-film mulching is an effective agronomic practice in the cultivation system of P. palustre, of which black-film mulching is the most common. However, fewer researches have been focused on the use of other colors of plastic films in P. palustre cultivation. In this study, different colors (white, black, red, and green) of plastic film were adopted, and the effects of different colors of plastic film mulching on the soil temperature, yield, and metabolites of P. palustre were investigated. The results showed that the fresh weight of a single plant of the green film treatment was significantly higher than that of the white film treatment (n = top 28). Based on the results of three temperature measurements, the soil temperature was almost the highest in the red film treatment and lowest in the white film treatment. The metabolomic analysis revealed that a total of 103 differential metabolites were identified. Among these, the gluconic acid, deoxyribose, and N-Acetylmannosamine in the red film treatment presented the highest abundance compared with the other treatments, meanwhile, the abundances of the five monosaccharides in the red film treatment were significantly higher than those of the green film treatment. Moreover, the sucrose, trehalose, and D-(+)-trehalose in the green film treatment exhibited the highest abundance, and the abundances of eight different amino acids in the red film treatment were almost the lowest while those in the black film treatment were almost the highest. Further analysis of the membership function values indicated that the black and red film treatments might be more suitable for the cultivation and quality production of P. palustre in comparison with the other two treatments. This study will provide a theoretical basis for improving the efficient cultivation technology of P. palustre and forming a theoretical system of P. palustre film mulching cultivation.

Complete chloroplast genome sequence of Pinus tabuliformis var. henryi (Mast.) C.T.Kuan 1983 (Pinaceae)

Pinus tabuliformis var. henryi (Mast.) C.T.Kuan 1983 is an endemic and rare subtropical pine, mainly distributed in central China. In this study, we sequenced the complete chloroplast (cp) genome of P. tabuliformis var. henryi and reported it for the first time. The cp genome was 119,634 base pairs (bp) in total length, including two inverted repeats (IRs, 495 bp), separated by a large single-copy region (LSC, 65,600 bp) and a small single-copy region (SSC, 53,044 bp). There are 114 different genes in the cp genome of P. tabuliformis var. henryi, including 74 protein-coding genes, 36 transfer RNA genes, and four ribosomal RNA genes. The overall GC content of the cp genome was 38.5%. Our phylogenetic analysis of P. tabuliformis var. henryi demonstrated that it was closely related to P. tabuliformis and could be used to identify and analyze its genetic diversity, which was expected to provide new data for taxonomic and phylogenetic studies of Pinus.

The complete plastid genome and characteristics analysis of Achillea millefolium

Achillea is a crop with Chinese herbal characteristics and horticultural values. Its leaves and flowers contain aromatic oil, and the ripe herb can also be used as medicine to induce sweat and relieve rheumatic pains. It is seen cultivated in gardens all over China. Currently, the most comprehensive chloroplast genome sample involved in the study refers to New World clades of Achillea, which are used for marker selection and phylogenetic research. We completely sequenced the chloroplast genomes of Achillea millefolium. These sequencing results showed that the plastid genome is 149,078 bp in size and possesses a typical quadripartite structure containing one large single copy (LSC) with 82,352 bp, one small single copy (SSC) with 18,426 bp, and a pair of inverted repeat (IR) regions with 24,150 bp in Achillea millefolium. The chloroplast genome encodes a common number of genes, of which 88 are protein-coding genes, 37 transfer ribonucleic acid genes, and 8 ribosomal ribonucleic acid genes, which are highly similar in overall size, genome structure, gene content, and sequence. The exact similarity was observed when compared to other Asteraceae species. However, there were structural differences due to the restriction or extension of the inverted repeat (IR) regions-the palindromic repeats being the most prevalent form. Based on 12 whole-plastomes, 3 hypervariable regions (rpoB, rbcL, and petL-trnP-UGG) were discovered, which could be used as potential molecular markers.

Integrating LC-MS and HS-GC-MS for the metabolite characterization of the Chinese medicinal plant Platostoma palustre under different processing methods

Platostoma palustre (or Mesona chinensis Benth) is an important medicinal and edible plant in China and Southeast Asian countries. To study the effects of different processing methods on the quality, nutrition, and flavor of P. palustre, we adopted the LC-MS and HS-GC-MS to compare the influences of tedding (S), sweating (M), and drying (H) on the metabolites and volatile substances of P. palustre. Biochemical determinations revealed that the M treatment could promote the accumulation of the contents of total sugar, soluble sugar, and total pectin compared with the H and S treatments but decrease the total flavonoid contents. LC-MS and HS-GC-MS uncovered 98 differential metabolites and 27 differential volatile substances among the three treatments, respectively. Overall, the M treatment facilitated the stabilization and improvement of the quality of polysaccharides and volatile substances, while the H treatment could promote the level of amino acids in P. palustre. The current study provided a theoretical reference for establishing standardized processing methods and sustaining the quality stability of P. palustre in future.

Mitochondrial genome characteristics and phylogenetic analysis of the medicinal and edible plant Mesona chinensis Benth

Mesona chinensis Benth (MCB) (or Platostoma palustre or Platostoma chinense) is an important edible and medicinal plant in China. However, the mitochondrial genome (mitogenome, or mtDNA) of MCB has not been characterized or reported yet. In this study, we first sequenced and characterized the complete mitogenome of MCB. The MCB mitogenome was 494,599 bp in length and encoded 59 genes containing 37 protein-coding genes (PCGs), 19 tRNAs, and 3 rRNAs. Gene transfer analysis revealed that a total of 12 transfer segments with more than 93% identity (total length of 25,427 bp) were detected in the MCB mitogenome. Simple sequence repeats (SSR) analysis showed that 212 simple sequence repeats (SSR) were identified. Repeat sequence analysis revealed 305 repeat sequences (158 forward and 147 palindromic repeats) ranging from 30 bp to 48,383 bp and the 30-39 bp repeats were the majority type. Relative synonymous codon usage (RSCU) analysis uncovered that in total, 9,947 codons were encoding the protein-coding genes (PCGs). Serine (909, 9.1%) and leucine (879, 8.8%) were the two most abundant amino acids, while terminator (32, .3%) was the least abundant amino acid. Ka/Ks analysis indicated that almost all genes were subject to purification selection, except ccmB. Analysis of Lamiaceae mitogenomes constitution revealed that atpB and atpE were unique to the Rotheca serrata and Salvia miltiorrhiza mitogenomes. mttB gene loss was unique to the Boea hygrometrica mitogenome. The core fragments of the Lamiaceae mitogenomes harbored a higher GC content than the specific and variable fragments. In addition, phylogenetic analysis revealed that MCB was closely related to Salvia miltiorrhiza based on the mitogenomes. The current study provided valuable genomic resources for understanding and utilizing this important medicinal plant in the future.

Plastome-based phylogeny and biogeography of Lactuca L. (Asteraceae) support revised lettuce gene pool categories

This study generated and analyzed complete plastome and internal transcribed spacer (ITS) data of 46 Lactuca species, 13 African endemic (AE) Lactuca species, and 15 species from eight related genera in Lactucinae. The new plastome and nuclear ITS sequences were then used to reconstruct the phylogenetic relationships of Lactuca species. The whole-plastome data were used to estimate divergence time and ancestral area reconstruction of the identified major Lactuca lineages. The results showed that Lactuca species are generally similar in plastome size, Guanine and Cytosine (GC) content, gene structure, and categories, although crop lettuce (Lactuca sativa L.) and its gene pool relatives were found to have one unique pseudogene (ψ ndhF), and accD, atpF, cemA, clpP, and rpl22 showed signs of positive selection. Our phylogenomic analysis demonstrated that Lactuca is monophyletic after excluding Lactuca alatipes Collett and Hemsl and AE Lactuca species. AE Lactuca species are morphologically distinct from core Lactuca lineage and need to be excluded from Lactua. The core Lactuca species most likely originated from Asia-Temperate W ~6.82 Mya and then dispersed globally and formed nine clades. Finally, the lettuce gene pool concept was amended according to the phylogenetic and historical biogeographic analyses. This study revised the circumscription of Lactuca, revealed robust phylogenetic relationships within the genus, and provided insights into Lactucinae phylogeny. The lettuce gene pool species could be used as potential genetic resources for lettuce breeding.