Genetic relationships among Glycyrrhiza plants determined by RAPD and RFLP analyses

Use of scanning electron microscopy to analyze sculpturing pattern and internal features of pollen grain wall in some members of Astragaleae (subfamily: Papilionoidae)

Palynological features of tribe Astagaleae L. have been observed with scanning electron microscopy (SEM), to assess features that can be used to re-examine the placement and taxonomic position of tribe. The palynomorph attributes of 10 species included in three genera of Astragaleae (Astragalus L., Glycyrrhiza L., and Oxytropis DC.) are investigated. The assignment of genus Oxytropis in tribe Astragaleae was also reevaluated based on pollen characters. Pollen appear to be prolate, prolate-spheroidal, and subprolate. Polar axis size (P) varies from 31.3 μm ±1 to 17.5 μm ±1.4 and equatorial axis size (E) varies from 22.2 μm ±1.8 to 13.1 μm ±0.9. Prominent apertures found consistently dispersed along the surface of pollen. Three kinds of ornamentation pattern were recorded, that is, reticulate or reticulate-perforate and perforate. The studied species display variation in equatorial and polar diameter, aperturation and sculpturing pattern, exine thickness, and pollen shape. On the basis of descriptive pollen features, a dichotomous taxonomic key and UPGMA analysis has been made for effortless and quick identification. The study concluded that disparities of the entire features are typically unrelenting and concerned with the species and shows potential systematic significance. The combination of palynological attributes in association with additional traits has prospective for systematic identification at species and genus level.

Association analysis and molecular tagging of phytochemicals in the endangered medicinal plant licorice (Glycyrrhiza glabra L.)

Licorice (Glycyrrhiza glabra L.) is a medicinal plant species valued in many countries in Asia and Europe for its phytochemical characteristics. Licorice biodiversity is becoming threatened nowadays in Iran due to increasing demand and a drastic decline of its natural habitats. Therefore, licorice domestication would be necessary in the near future, and molecular breeding would help to introduce genotypes suitable for cultivation. The present study was carried out with 170 individual licorice plants sampled in the wild in 59 localizations in 21 provinces of Iran. The association of 436 polymorphic AFLP markers, produced by 15 primer combinations (EcoRI/MseI), with six phenotypic phytochemical traits was studied. The AMOVA analysis show gene diversity among and within localizations. The population structure analysis identified two main sub-populations with significant genetic variation. Significant associations were identified between three markers (E3/M40-4, E34/M4-12 and E12/M31-15) and glycyrrhizin concentration, and between four markers (E11/M34-12, E11/M34-15, E9/M7-29, and E9/M7-30) and phenolic compounds contents. Markers detected can be useful in the domestication of licorice as well as in breeding programs. Licorice sampled in four localizations (KBA1, KBA2, SKh2 and Fa1) were found to be superior in terms of glycyrrhizin and antioxidants content, and therefore they can be considered as elite genotypes which could be included in the domestication process.

Chloroplast Phylogenomics Reveals the Intercontinental Biogeographic History of the Liquorice Genus (Leguminosae: Glycyrrhiza)

The liquorice genus, Glycyrrhiza L. (Leguminosae), is a medicinal herb with great economic importance and an intriguing intercontinental disjunct distribution in Eurasia, North Africa, the Americas, and Australia. Glycyrrhiza, along with Glycyrrhizopsis Boiss. and Meristotropis Fisch. & C.A.Mey., comprise Glycyrrhiza s.l. Here we reconstructed the phylogenetic relationships and biogeographic history in Glycyrrhiza s.l. using sequence data of whole chloroplast genomes. We found that Glycyrrhiza s.l. is sister to the tribe Wisterieae and is divided into four main clades. Clade I, corresponds to Glycyrrhizopsis and is sister to Glycyrrhiza sensu Meng. Meristotropis is embedded within Glycyrrhiza sensu Meng, and these two genera together form Clades II-IV. Based on biogeographic analyses and divergence time dating, Glycyrrhiza s.l. originated during the late Eocene and its most recent common ancestor (MRCA) was distributed in the interior of Eurasia and the circum-Mediterranean region. A vicariance event, which was possibly a response to the uplifting of the Turkish-Iranian Plateau, may have driven the divergence between Glycyrrhiza sensu Meng and Glycyrrhizopsis in the Middle Miocene. The third and fourth main uplift events of the Qinghai-Tibetan Plateau may have led to rapid evolutionary diversification within Glycyrrhiza sensu Meng. Subsequently, the MRCA of Clade II might have migrated to North America (G. lepidota) via the Bering land bridge during the early Pliocene, and reached temperate South America (G. astragalina) by long-distance dispersal (LDD). Within Clade III, the ancestor of G. acanthocarpa arrived at southern Australia through LDD after the late Pliocene, whereas all other species (the SPEY clade) migrated to the interior of Eurasia and the Mediterranean region in the early Pleistocene. The MRCA of Clade IV was restricted in the interior of Eurasia, but its descendants have become widespread in temperate regions of the Old World Northern Hemisphere during the last million years.

Development of cleaved amplified polymorphic sequence (CAPS) and high-resolution melting (HRM) markers from the chloroplast genome of Glycyrrhiza species

Licorice (Glycyrrhiza glabra) is an important medicinal crop often used as health foods or medicine worldwide. The molecular genetics of licorice is under scarce owing to lack of molecular markers. Here, we have developed cleaved amplified polymorphic sequence (CAPS) and high-resolution melting (HRM) markers based on single nucleotide polymorphisms (SNP) by comparing the chloroplast genomes of two Glycyrrhiza species (G. glabra and G. lepidota). The CAPS and HRM markers were tested for diversity analysis with 24 Glycyrrhiza accessions. The restriction profiles generated with CAPS markers classified the accessions (2-4 genotypes) and melting curves (2-3) were obtained from the HRM markers. The number of alleles and major allele frequency were 2-6 and 0.31-0.92, respectively. The genetic distance and polymorphism information content values were 0.16-0.76 and 0.15-0.72, respectively. The phylogenetic relationships among the 24 accessions were estimated using a dendrogram, which classified them into four clades. Except clade III, the remaining three clades included the same species, confirming interspecies genetic correlation. These 18 CAPS and HRM markers might be helpful for genetic diversity assessment and rapid identification of licorice species.

Species identification of licorice using nrDNA and cpDNA genetic markers

For the accurate identification of medicinal licorice species, nucleotide sequences of four types of DNA regions were researched for 205 specimens, including three species used as licorice: Glycyrrhiza uralensis, Glycyrrhiza glabra, and Glycyrrhiza inflata. The four DNA regions were the internal transcribed spacer (ITS) on nuclear ribosomal DNA, the rbcL gene, the matK gene, and the trnH-psbA intergenic region on chloroplast DNA (cpDNA). Ten genotypes were consequently recognized as combinations of the sequence data obtained from the four DNA regions. Species-specific genotypes were defined from the frequency of the appearance of species in each genotype and from the phylogenetic relationships of the 10 genotypes. This revealed the possibility of identifying licorice species based on the 10 genotypes. Next, comparison of species identifications by each DNA region suggested that efficient identification of licorice species is possible using the genetic information obtained from the ITS and trnH-psbA intergenic region. Additionally, concerning the phylogenetic relationships of the Glycyrrhiza species used as licorice, it is suggested from the genetic information of the four types of DNA regions that G. glabra is more closely related to G. inflata than to G. uralensis. In the G. uralensis examined, four genotypes were recognized as intra specific variations. The appearance frequency of each genotype in G. uralensis differed according to the area in China. G. uralensis may have expanded its distribution areas from western to eastern China because many licorices with the phylogenetic ancestral genotype were observed in western areas, while many with the derivative genotype were observed in eastern areas.

[Molecular biological studies on diversity of secondary metabolism in medicinal plants and application to the production in transgenic plants]

A molecular biological approach was applied to the study of diversity and regulation of secondary metabolism in medicinal plants at various levels. For the inter-species diversity, RFLP (restriction fragment length polymorphism) and RAPD (random amplified polymorphic DNA) analyses of genomic DNA were performed on the plants, belonging to the same genus or family and containing related compounds. Phylogenetic trees of lupin alkaloid containing plants and other medicinal plants, based on RFLP and/or RAPD profiles, showed the relationship between the diversities in genomes and secondary metabolisms. The chemotypes regarding anthocyanin production in Perilla frutescens var. crispa, were subjected to the study on intra-species diversity. The structural genes and the regulatory genes involved in anthocyanin biosynthesis were isolated and their expression in red and green forms was determined by Northern blot analysis. The expression of all structural genes examined was co-ordinately regulated in form-specific manner and by light illumination. The anthocyanin production was enhanced in transgenic plants over-expressing Myc homologue genes from perilla. These results suggested that a protein complex including bHLH factors might regulate the expression of a series of structural genes. Additionally, cDNAs coding anthocyanin 5-O-glucosyltransferase and anthocyanidin synthase were isolated and characterized using recombinant proteins for the time. In conclusion, it was indicated that the molecular biological techniques are powerful tools for the investigation of diversity and regulation of and for the genetic engineering of secondary metabolism in medicinal plants.

Genetic and alkaloid analysis of Papaver species and their F1 hybrid by RAPD, HPLC and ELISA

Total DNA was extracted from the leaves of a F1 hybrid and its parents, Papaver bracteatum Lindle and P. pseudo-orientale Medw. Analysis of random-amplified polymorphic DNA (RAPD) using ten arbitrary oligonucleotide 10-mers, showed that F1 hybrid was confirmed to be genetically intermediate of both parental plants compared with the genetic distance between F1 hybrid and individual parents. Furthermore, the comparison of the band patterns between a F1 hybrid, P. bracteatum and P. pseudo-orientale clearly showed that part of the bands of both parents were induced into a F1 hybrid. The content of thebaine was determined by HPLC and ELISA used anti-thebaine monoclonal antibody.

Micropropagation ofPanax notoginseng by somatic embryogenesis and RAPD analysis of regenerated plantlets

Somatic embryogenesis was induced in callus tissues derived from young flower buds ofPanax notoginseng via callus within 18 weeks of culture. The mature somatic embryos were germinated on half-strength Murashige and Skoog's (MS) medium supplemented with gibberellic acid A₃(GA) and 6-benzyladenine (BA). The most suitable medium for optimal root formation proved to be MS medium supplemented with 1-naphthaleneacetic acid (NAA). Total DNA was extracted from the leaves of the regenerated plantlets ofP. notoginseng. Analysis of random-amplified polymorphic DNA (RAPD) using 21 arbitrary oligonucleotide 10-mers, showed the genetic homogeneity ofP. notoginseng. The amplification products were monomorphic for all of the plantlets ofP. notoginseng regenerated by embryogenesis, suggesting that somatic embryogenesis can be used for clonal micropropagation of this plant.