Genera Of Lamiaceae Research Articles

Study on anti-inflammatory activity of phenolic acids from Leucas ciliata

The chemical constituents from Leucas ciliata belonging to Leucas genus in Lamiaceae were systematically explored by silica gel column chromatography, ODS column chromatography, Sephadex LH-20 gel column chromatography, and preparative high performance liquid chromatography, and seventeen phenolic acids were isolated. The chemical structures of the compounds were identified by their physicochemical properties, spectroscopic data, and literature. They were 4-hydroxyphenethyl ethyl succinate(1), 4-hydroxyphenethyl methyl succinate(2), 2-(4-hydroxyphenyl) ethyl acetate(3), p-hydroxyphenylethyl anisate(4), cassia cis-trans diphenylpropanoid(5), p-coumaric acid(6), 3,4-dihydroxybenzenepropionic acid methyl ester(7), caffeic acid(8), trans-p-hydroxyl ethyl cinnamate(9), methyl p-hydroxybenzeneacetate(10), 4-hydroxyphenethyl alcohol(11), syringic acid(12), vanillin(13), protocatechuic acid(14), salicylic acid(15), p-hydroxybenzaldehyde(16), and diorcinol(17). Among them, compound 1 was new, and compounds 2-10, 12, 14, and 16-17 were isolated from the plants belonging to Leucas genus for the first time. All compounds were obtained from L. ciliata for the first time. The anti-inflammatory activity of compounds 1-17 on NO production in lipopolysaccharide(LPS)-induced mouse leukemia cells of monocyte macrophage(RAW264. 7) cells was evaluated. The results showed that compounds 5, 7, and 9 exhibited significant anti-inflammatory activity, with IC50values of(10. 14±0. 36)-(21. 17±0. 11) μmol·L~(-1).

Anti-Leishmania effect of icetexanes from Salvia procurrens

Background and purposeLeishmaniasis is a globally prevalent vector-borne disease caused by parasites of the genus Leishmania. The available chemotherapeutic drugs present problems related to efficacy, emergence of parasite resistance, toxicity and high cost, justifying the search for new drugs. Several classes of compounds have demonstrated activity against Leishmania, including icetexane-type diterpenes, previously isolated from Salvia and other Lamiaceae genera. Thus, in this study, compounds of Salvia procurrens were investigated for their leishmanicidal and immunomodulatory activities. MethodsThe exudate of S. procurrens was obtained by rapidly dipping the aerial parts in dichloromethane. The compounds were isolated by column and centrifugal planar chromatography over silica gel. The effects on L. amazonensis growth, survival, membrane integrity, reactive oxygen species (ROS) generation, mitochondrial membrane potential and cytotoxicity of the compounds towards human erythrocytes, peripheral blood mononuclear cells and macrophages were evaluated. The effects on intracellular amastigote forms, nitric oxide (NO) and TNF-α production were also investigated. ResultsThe exudate from the leaves afforded the novel icetexane 7-hydroxyfruticulin A (1) as well as the known demethylisofruticulin A (2), fruticulin A (3) and demethylfruticulin A (4). The compounds (1–4) were tested against promastigotes of L. amazonensis and showed an effective inhibition of the parasite survival (IC50 = 4.08–16.26 μM). In addition, they also induced mitochondrial ROS production, plasma membrane permeability and mitochondrial dysfunction in treated parasites, and presented low cytotoxicity against macrophages. Furthermore, all diterpenes tested reduced the number of parasites inside macrophages, by mechanisms involving TNF-α, NO and ROS. ConclusionThe results suggest the potential of 7-hydroxyfruticulin A (1) as well as the known demethylisofruticulin A (2),fruticulin A (3) and demethylfruticulin A (4) as candidates for use in further studies on the design of anti-leishmanial drugs.

The complete chloroplast genome of Orthosiphon aristatus (Blume) Miq. (Lamiaceae)

Orthosiphon aristatus (Blume) Miq. 1858 is a Lamiaceae plant. It is mainly found in southern China. It is an excellent medicinal plant. The complete chloroplast genome of O. aristatus is 152,155 bp in length, with an average depth of 287×, and the GC content was 37.86%, a large single-copy (LSC) region of 83,098 bp, a small single-copy (SSC) region of 17,665 bp, and an inverted repeats (IRs) region of 25,696 bp make up the genome’s typical tetragonal shape. In addition, the genome consisted of 128 genes, including 85 protein-coding genes, 35 transfer RNA (tRNA), and eight ribosomal RNA (rRNA) genes. A monophyletic group was established by O. aristatus and 13 plants from five genera of Lamiaceae, according to the phylogenetic tree. In contrast, an isolated monophyletic group was formed by the alien plant Cinnamomum aromaticum. The ML tree bootstrap value was relatively high, and O. aristatus was most closely related to Ocimum tenuiflorum and Ocimum basilicum. This study can help with species identification and phylogenetic analysis within O. aristatus and Lamiaceae species.

Towards a global perspective for Salvia L.: Phylogeny, diversification and floral evolution.

Salvia is the most species-rich genus in Lamiaceae, encompassing approximately 1000 species distributed all over the world. We sought a new evolutionary perspective for Salvia by employing macroevolutionary analyses to address the tempo and mode of diversification. To study the association of floral traits with speciation and extinction, we modelled and explored the evolution of corolla length and the lever-mechanism pollination system across our Salvia phylogeny. We reconstructed a multigene phylogeny for 366 species of Salvia in the broad sense including all major recognized lineages and 50 species from Iran, a region previously overlooked in studies of the genus. Our comprehensive sampling of Iranian species of Salvia provides higher phylogenetic resolution for southwestern Asian species than obtained in previous studies. Our phylogenetic data in combination with divergence time estimates were used to examine the evolution of corolla length, woody versus herbaceous habit, and presence versus absence of a lever mechanism. We investigated the timing and dependence of Salvia diversification related to corolla length evolution through a disparity test and BAMM analysis. A HiSSE model was used to evaluate the dependency of diversification on the lever-mechanism pollination system in Salvia. A medium corolla length (15-18 mm) was reconstructed as the ancestral state for Salvia with multiple shifts to shorter and longer corollas. Macroevolutionary model analyses indicate that corolla length disparity is high throughout Salvia evolution, significantly different from expectations under a Brownian motion model during the last 28 million years of evolution. Our analyses show evidence of a higher diversification rate of corolla length for some Andean species of Salvia compared to other members of the genus. Based on our tests of diversification models, we reject the hypothesis of a direct effect of the lever mechanism on Salvia diversification. Therefore, we suggest caution in considering the lever-mechanism pollination system as one of the main drivers of speciation in Salvia.

Infraspecific Anatomical Study of Salvia limbata C. A. Mey. (Lamiaceae) in Iran

Salvia limbata is a medicinal plant of the Lamiaceae family that is naturally distributed in various regions of Iran and neighboring countries. In the current evaluation, the leaf blade and petiole anatomical variables were examined in eight Iranian S. limbata populations to explore their taxonomic significance and interpopulation variations. The evaluated populations were harvested from three subprovinces of the Irano-Turanian province. The plant samples were fixed in formaldehyde 90%, ethanol 5%, acetic acid 5% solution, and the hand cross sections of the blade and petiole were double stained with carmine and methylene blue. Data were analyzed using PAST ver. 2.1 and findings revealed that all qualitative variables were invariable between populations, except for the shape of the leaf blade and the epidermal cells of the petiole. Most quantitative traits varied among the considered populations by principal component analysis (PCA) and divided the investigated characteristics into seven components, where two first components had more than 80% of the total variation. In PCA loading, most of the characteristics assessed were negatively correlated. According to UPGMA dendrogram and PCA plot, the populations were clustered into three groups. The PCA biplot revealed the distinct characteristic(s) for each classified group. The clustering patterns of these populations were not in agreement with the geographical distance and phytogeographic similarity between the populations. Several anatomical characteristics were found similar to those recorded in some Lamiaceae genera and lacked taxonomic value, whereas others had taxonomic importance at the infraspecific level. According to a phytogeographic survey and a previous study of molecular genetic diversity, it can be suggested that genetic background can create enough anatomical adaption in populations of S. limbata to establish itself in a wide range of habitats. Meanwhile, the microhabitat has a powerful influence on the anatomical structure.

Salinity affects eco-physiological aspects and biochemical compositions in chia (Salvia hispanica L.) during germination and seedling growth

• Chia plant was more sensitive to salinity during seedling growth stage compared to the germination's one. • During germination, antioxidant enzymes activity increased with increasing salinity up to 200 mM. • At seedling growth, the highest amount of total phenols and flavonoid was achieved at the 40 mM salinity level. • During seedling growth, the highest amount of soluble sugars, nitrogen and protein was obtained at salinity levels less than 40 mM. • Based on Gompertz model's, salinity reduced germination and seedling establishment and increased the time to reach the maximum value of these traits. Salvia hispanica (chia), a genus of Lamiaceae is a super food plant, which could be used as an oilseed and industrial medicinal crop in agro-ecosystems. High salinity inhibits chia seed germination and seedling growth, but the plant is moderately tolerant to salt. It is therefore important to study the role of antioxidant enzymes, biologically active compounds, and other eco-physiological responses related to salinity tolerance in this plant. However, despite of many nutritional benefits, there is a lack of information about chia seeds and seedling eco-physiology. Two experiments were conducted based on the completely randomized design in three replications. In the first experiment, salinity tolerance of chia was evaluated using final germination percentage, mean germination time, germination rate, seedling vigor and antioxidant enzymes activity at germination stage at six levels of sodium chloride (NaCl) solutions including (0, 50, 100, 150, 200, 250 mM). In the second experiment, salinity tolerance of chia seedling were evaluated at seven levels of NaCl solutions up to 150 mM (0, 20, 40, 60, 80, 100 and 150 mM). Results revealed that salinity significantly affected all traits except for seedling water content and photosynthetic water use efficiency at the seedling stage. Among seed germination parameters, only mean germination time increased by 77.2% at 200 mM salinity concentrations compared to control. Seed soluble protein increased by 37.50% at 50 mM NaCl and then declined by at 150 mM 46.36%. The activity of catalase and peroxidase increased 125.5% and 99.4% with increasing NaCl concentration from 150 to 200 mM, but malondialdehyde activity decreased 53.9%. It was revealed that secondary metabolites (total phenol and flavonoids) in chia seedlings increased by 55.0% and 9.9% at 40 mM, NaCl concentration while soluble sugars, nitrogen and protein content declined by 73.0, 57.6 and 57.6% at 150 mM compared to control salinity treatment. In addition, salinity had a negative effect on stomatal conductance, photosynthesis and transpiration rate, which are key players in salinity stress tolerance mechanisms of chia seedlings, especially up to 40 mM salt concentrations. Non-linear gompertz function provided an excellent description for chia seed germination (R 2 adj ≥ 0.97 and RMSE ≤ 4.49) and seedling establishment (R 2 adj ≥ 0.93 and RMSE ≤ 5.41) under salinity condition. A significant reduction in seed vigor index (40.4%) occurred at 50 mM NaCl concentration. chia seedlings below 40 mM NaCl concentration may encounter less detrimental effect.

Paraphlomishsiwenii (Lamiaceae), a new species from the limestone area of Guangxi, China.

The indumentum of nutlets is shown to be of phylogenetic importance in previous molecular phylogenetic studies of Paraphlomis, a genus of Lamiaceae with approximately 30 species distributed mainly in southern China and Southeast Asia. Nearly half the species of Paraphlomis are known from limestone areas. In this study, we described and illustrated a new species, P.hsiwenii, from the karst mountain forests in Guangxi Zhuang Autonomous Region, China. Our molecular phylogenetic analyses revealed that P.hsiwenii is recovered in a clade consisting of species with hairy nutlets. The new species is morphologically most similar to P.pagantha from the same clade, but they differ in the morphology of lamina bases, length of pedicels and calyces, as well as the morphology of upper corolla lips.

ABIETANE QUINONE DITERPENES WITH ANTITUBERCULOSIS ACTIVITY ISOLATED FROM THE GENUS SALVIA

The name Salvia, the largest genus of Lamiaceae, derives from the Latin "salvere" (= to feel good, healthy). In the Mediterranean basin, S. officinalis has been used since the time of the ancient Egyptians for medicinal purposes. Pliny the Elder was the first known author to describe a plant called "Salvia" by the Romans. Recent scientific research has confirmed the antituberculosis properties of numerous species present in the traditional ethnobotany.

Comparative study of genetic diversity using RAPD markers in Salvia (Lamiaceae)

Salvia has a high degree of environmental compatibility and is widespread around the world, especially in tropical and temperate regions. It is represented by 61 species in Iran including 19 endemic species. Salvia species are mostly shrubs or subshrubs, occasionally herbs, typically perennial, sometimes biennial or annual, and often aromatic. The genus has high medicinal, commercial and horticultural value. It is the largest and one of the taxonomically complicated genus of Lamiaceae. To determine the genetic diversity and understand the species’ limits within the Iranian Salvia, we produced both morphological and molecular data using 145 randomly collected plants representing 30 species from 18 provinces of Iran. A total of 107 reproducible bands were generated by 10 of 25 random amplified polymorphic DNA (RAPD) primers, with an average of 10.7 bands/primer and 44% polymorphism. Largest number of effective alleles (Ne), genetic diversity (H), and Shannon Index (I) were shown by S. reuterana. Our data depicted highest similarity between S. suffruticosa and S. hydrangea and lowest between S. aristata and S. oligphylla. Salvia limbata showed relatively low level of genetic variation. Finally, the Neighbor Joining (NJ) trees based on RAPD markers data divided the populations into two different clusters, indicating their genetic difference which is discussed in details.

A preliminary phylogenetic study of Paraphlomis (Lamiaceae) based on molecular and morphological evidence

Paraphlomis is a genus of Lamiaceae with about 30 species distributed mainly in subtropical China. In this study, we carried out the first molecular phylogenetic analyses to elucidate the relationships within the genus based on two nuclear and four plastid DNA regions. Our results, which recovered a species of Matsumurella within Paraphlomis, indicate that the genus is not monophyletic. The two sections and most of the series previously described within the genus are also shown to be polyphyletic. Combining with morphological evidence, our study indicates that nutlet morphology rather than calyx morphology is of phylogenetic value for the infrageneric classification of Paraphlomis. Moreover, P. jiangyongensis, a new species from southern China, is here described, and P.coronata, formerly treated as a variety of P.javanica, is here resurrected as a distinct species within the genus.

Characterization of the complete plastid genome of Craniotome Rchb., a monotypic genus of Pogostemoneae, Lamiaceae

Craniotome Rchb. is a monotypic genus of Lamiaceae. In this study, the complete plastid genome of the species C. furcata (Link) Kuntze was sequenced and assembled. The plastid genome obtained is 152,521 bp in length, including a pair of inverted repeat (IRa and IRb) regions of 25,596 bp, a large single-copy (LSC) region of 83,690 bp, and a small single-copy (SSC) region of 17,639 bp. The genome encoded 113 unique genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes. The overall GC content of the genome obtained is 38.29%. The phylogenetic analysis based on 37 plastid genome of Lamiaceae revealed that the genus Craniotome was sister to the Anisomeles-Pogostemon clade with strong support.

Pollen morphological traits analysis of eighteen 'Nepeta' species in Iran

Nepeta is one of the largest genera of Lamiaceae, which is widely distributed in Iran. Several species of the genus are traditionally used as culinary, industrial, and medicinal plants. In the present study, we examined fourteen qualitative and quantitative pollen morphological characters of twenty-four populations of eighteen Nepeta using light and scanning electron microscope. The pollen grains are radially symmetric, isopolar, and hexacolpate in all species. We have found that the quantitative features vary among the studied taxa. According to PCA analysis, the colpus length and width are the most variable traits. Polar view shapes in all the studied taxa are circular, while the equatorial view is prolate-spheroidal, subprolate, perprolate, and prolate. We determined microreticulate and bireticulate exine sculpturing, and the bireticulate type was dominant. We revealed that polar and equatorial axes length of pollen grains varied between populations of the same species, and they, therefore, should be ignored in taxonomical identification of species. The polar view was similar in all the studied pollen grains and could not be considered as a diagnostic trait. The equatorial shape was stable between populations of the same species, and this was taxonomically important, while we registered some infraspecific variations in exine sculpture. Our cluster of taxa based on the pollen morphology is not in concordance with the traditional sectional classification of the genus.

Composition of the essential oil of Stachys sericantha, S. gaziantepensis, and S. mardinensis (Lamiaceae) from Turkey

ABSTRACTThe genus Stachys L. one of the largest genera of Lamiaceae and Stachys species are used by many people for the therapeutic value of their essential oils. In this study, water-distilled essential oil of three species of Stachys was analysed. The analysis was performed by using gas chromatography-flame ionisation detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS) systems simultaneously. The major components found were hexadecanoic acid (23.7%), dodecanoic acid (11.3%), and caryophyllene oxide (10.7%) for S. sericantha P.H. Davis (endemic); α-pinene (53%), β-pinene (8.2%) for S. gaziantepensis M. Dinc and S. Doğu (endemic); Menthyl acetate (15.3%), isomenthone (15.0%), pulegone (10%), spathulenol (7.0%), and caryophyllene oxide (6.7%) for S. mardinensis (Post) R. Mill.

Great Expectations: Correlations between Pollinator Assemblages and Floral Characters in Lamiaceae

Premise of research. Pollination syndromes are used to infer pollinators from floral attributes when field observations of floral visitors are lacking. Such inferences are often found to be incorrect or too generalized. To investigate the relationship between pollinators and observable differences in a genus of Lamiaceae with flowers that appear ornithophilous and entomophilous, we experimentally quantified floral morphology and pollinator assemblages in a phylogenetic perspective.Methodology. Floral morphology was examined using multivariate analysis of geometric morphometrics (corolla shape described by landmarks), linear dimensions, and nonmetric attributes for 17 species of Prostanthera. Pollination effectiveness was determined through censuses of floral visitors and interactions by pollinators with flowers, and multivariate statistics were used to examine correspondence between these data and nonlandmark characters. Ancestral state reconstruction was performed using geometric morphometric data and a ...

Anti-HIV activity of Hyptis Jacq. (Lamiaceae)

Hyptis species are known to be used in folk medicine to treat various diseases such as flu and constipation (H. fruticosa), respiratory diseases (H. macrostachys), stomach and intestinal disorders (H. martiusii), colic and liver disease (H. pectinata), nasal and ear disorders (H. umbrosa) and fever (H. suaveolens) [1]. It is a genus of Lamiaceae, comprising of approximately 144 species which are distributed in tropical and subtropical regions. Hyptis radicans (Pohl) Harley & J.F.B. Pastore, H. lappulacea Mart. ex Benth, H. multibracteata Benth. and H. comaroides (Briq.) Harley & J.F.B. Pastore, are species from the Atlantic Forest easily found in Paranapiacaba, SP, Brazil, except H. comaroides which is found in Southern Brazil, in a field area. Currently there is no literature describing the pharmacological potential about those species. Therefore the anti-HIV1 potential of hydroethanolic extracts was investigated. Plant material was collected, dried at 40 °C for a week, powdered and subjected to maceration in ethanol 70% for 7 days at room temperature in the dark. Extracts were lyophilized and all samples were dissolved in DMSO 10% to achieve concentrations of 0.25, 0.50, 0.75 and 1 mg/mL for an anti-HIV1 assay (Roche®). A Foscarnet standard (0.025 – 1 µg/mL) was used as a positive control. The crude extract that showed the lowest EC50 was from H. comaroides (EC50 33.9 µg/mL) followed by H. radicans (EC50 158.7 µg/mL), H. lappulacea (EC50 865.0 µg/mL) and H. multibracteata (EC50 1096.0 µg/mL). In comparison to the stardard Foscarnet (EC50 0.51 µg/mL) H. comaroides and H. radicans, both from Peltodon section, are promising species to search for substances with anti-HIV1 activity.

Phylogenetic Analysis of Selected Menthol-Producing Species Belonging to the Lamiaceae Family

Menthol is an organic compound with diverse medicinal and commercial applications, and is made either synthetically or through extraction from mint oils. The aim of the present study was to investigate menthol levels in selected menthol-producing species belonging to the Lamiaceae family, and to determine phylogenetic relationships of menthol dehydrogenase gene sequence among these species. Three genus of Lamiaceae, namely Mentha, Salvia, and Micromeria, were selected for phytochemical and phylogenetic analyses. After identification of each species based on menthol dehydrogenase gene in NCBI, BLAST software was used for the sequence alignment. MEGA4 software was used to draw phylogenetic tree for various species. Phytochemical analysis revealed that the highest and lowest amounts of both essential oil and menthol belonged to Mentha spicata and Micromeria hyssopifolia, respectively. The species Mentha spicata and Mentha piperita, which were assigned to one cluster in the dendrogram, contained the highest amounts of essential oil and menthol while Micromeria species, which was in the distinct cluster and placed in the farther evolutionary distance, contained the lowest amount of essential oil and menthol. Phylogenetic and phytochemistry analyses showed that essential oil and menthol contents of menthol-producing species are associated with menthol dehydrogenase gene sequence.

Reassessment of Melittis melissophyllum L. subsp. melissophyllum iridoidic fraction

The analysis of the polar fraction of Melittis melissophyllum L. subsp. melissophyllum led to the identification of several iridoid glycosides: monomelittoside (1), melittoside (2), harpagide (3), acetyl-harpagide (4) and ajugoside (5). Compounds 3 and 4 are considered marker compounds for the genus and, as well as compounds 1, 2 and 5, were already evidenced in a previous study on the nominal species. It was noteworthy of the presence of allobetonicoside (6) which was never reported for this genus. The isolation of 6 is very relevant because of its allose residue on the structure. Allose has been often found in the species of the subfamily Lamioideae even if it mostly regarded flavonoids considered of chemotaxonomical relevance for some correlated genera of Lamiaceae. Same as allosyl-glycosidic flavonoids, the presence of allosyl-glycosidic iridoids may also be an additional chemosystematic evidence of botanical relationships among Lamiaceae species and genera.

Towards Elucidating Carnosic Acid Biosynthesis in Lamiaceae: Functional Characterization of the Three First Steps of the Pathway in Salvia fruticosa and Rosmarinus officinalis.

Carnosic acid (CA) is a phenolic diterpene with anti-tumour, anti-diabetic, antibacterial and neuroprotective properties that is produced by a number of species from several genera of the Lamiaceae family, including Salvia fruticosa (Cretan sage) and Rosmarinus officinalis (Rosemary). To elucidate CA biosynthesis, glandular trichome transcriptome data of S. fruticosa were mined for terpene synthase genes. Two putative diterpene synthase genes, namely SfCPS and SfKSL, showing similarities to copalyl diphosphate synthase and kaurene synthase-like genes, respectively, were isolated and functionally characterized. Recombinant expression in Escherichia coli followed by in vitro enzyme activity assays confirmed that SfCPS is a copalyl diphosphate synthase. Coupling of SfCPS with SfKSL, both in vitro and in yeast, resulted in the synthesis miltiradiene, as confirmed by 1D and 2D NMR analyses (1H, 13C, DEPT, COSY H-H, HMQC and HMBC). Coupled transient in vivo assays of SfCPS and SfKSL in Nicotiana benthamiana further confirmed production of miltiradiene in planta. To elucidate the subsequent biosynthetic step, RNA-Seq data of S. fruticosa and R. officinalis were searched for cytochrome P450 (CYP) encoding genes potentially involved in the synthesis of the first phenolic compound in the CA pathway, ferruginol. Three candidate genes were selected, SfFS, RoFS1 and RoFS2. Using yeast and N. benthamiana expression systems, all three where confirmed to be coding for ferruginol synthases, thus revealing the enzymatic activities responsible for the first three steps leading to CA in two Lamiaceae genera.

Identity of Salvia weihaiensis (Lamiaceae) from China

Salvia Linnaeus (1753: 23) (tribe Mentheae, subfamily Nepetoideae) is by far the largest genus of Lamiaceae with approximately 1000 species (Alziar 1988–1993). Molecular phylogeny researches demonstrate that the genus is polyphyletic, and the clade “Salvia” in effect includes four distinct lineages, with intercalation of five other genera of tribe Mentheae (Walker et al. 2004, Walker & Sytsma 2007, Takano & Okada 2011, Will & Claßen-Bockhoff 2014). East Asia is one of three centers of diversity of Salvia with approximately 100 species (Walker et al. 2004), 82 species are native to China (Li & Hedge 1994, Hu et al. 2014). Additionally, S. coccinea Buc’hoz ex Etlinger (1777: 23) and S. tiliifolia Vahl (1794: 3), which are native to Central and South America, have naturalized successfully in China (Li & Hedge 1994, Hu et al. 2013).

Does the Arcto-Tertiary biogeographic hypothesis explain the disjunct distribution of Northern Hemisphere herbaceous plants? The case of Meehania (Lamiaceae).

Despite considerable progress, many details regarding the evolution of the Arcto-Tertiary flora, including the timing, direction, and relative importance of migration routes in the evolution of woody and herbaceous taxa of the Northern Hemisphere, remain poorly understood. Meehania (Lamiaceae) comprises seven species and five subspecies of annual or perennial herbs, and is one of the few Lamiaceae genera known to have an exclusively disjunct distribution between eastern Asia and eastern North America. We analyzed the phylogeny and biogeographical history of Meehania to explore how the Arcto-Tertiary biogeographic hypothesis and two possible migration routes explain the disjunct distribution of Northern Hemisphere herbaceous plants. Parsimony and Bayesian inference were used for phylogenetic analyses based on five plastid sequences (rbcL, rps16, rpl32-trnH, psbA-trnH, and trnL-F) and two nuclear (ITS and ETS) gene regions. Divergence times and biogeographic inferences were performed using Bayesian methods as implemented in BEAST and S-DIVA, respectively. Analyses including 11 of the 12 known Meehania taxa revealed incongruence between the chloroplast and nuclear trees, particularly in the positions of Glechoma and Meehania cordata, possibly indicating allopolyploidy with chloroplast capture in the late Miocene. Based on nrDNA, Meehania is monophyletic, and the North American species M. cordata is sister to a clade containing the eastern Asian species. The divergence time between the North American M. cordata and the eastern Asian species occurred about 9.81 Mya according to the Bayesian relaxed clock methods applied to the combined nuclear data. Biogeographic analyses suggest a primary role of the Arcto-Tertiary flora in the study taxa distribution, with a northeast Asian origin of Meehania. Our results suggest an Arcto-Tertiary origin of Meehania, with its present distribution most probably being a result of vicariance and southward migrations of populations during climatic oscillations in the middle Miocene with subsequent migration into eastern North America via the Bering land bridge in the late Miocene.