Assessment of genetic diversity and relationships among Salvia species using gene targeted CAAT box-derived polymorphism markers

To detect the genetic variation and relationships among different Salvia ecotypes/species, the gene targeted CAAT box derived polymorphism (CBDP) markers were employed in terms of their efficiency. In this study, 25 CBDP primers amplified a total of 323 different polymorphic fragments that discriminate all 26 Salvia ecotypes/species and produced an informative and differentiated dendrogram and population structure. The CBDP markers were found to be effective in Salvia genetic diversity estimation with regard to the averages polymorphism (100%), polymorphism information content (PIC = 0.89), marker index (MI = 4.5) and the effective multiplex ratio (EMR = 5.01) which were higher than other reported markers on Salvia. The extent of heterozygosity (0.034≤H≤0.223) and Shannon index (0.042≤I≤0.278) indicated a high level of genetic variation among Salvia species. The species containing the highest basic chromosome number (X = 12) revealed the highest values for the number of different (N_a) and effective (N _e) alleles, Shannon index (I), and heterozygosity (H). Additionally, the tetraploid species showed high values of N _a, N_e, I and H compared to the diploid species. Mean of gene differentiation (G_st) among Salvia species was 0.792, and the estimation of gene flow (N_m) was 0.13, indicating high genetic differentiation. Remarkably, similar results were obtained from the principal co-ordinate analysis (PCoA) as compared with the cluster analysis, in which all different Salvia species formed individual groups. In conclusion, because the CBDP markers are derived from the gene containing regions of the genome, consequently, the high genetic diversity among studied Salvia species would be more useful for crop improvement programmes, such as hybridization between species and QTL mapping. The potential of CBDPs for analysing the phylogeny and genetic diversity of Salvia species is another key result with practical implications.

Sex-differential reproduction success and selection on floral traits in gynodioecious Salvia pratensis

BACKGROUND

Gynodioecy, a sexual system with hermaphrodite and female individuals in a population, raises the question how the two sexual morphs are maintained. Salvia pratensis is a gynodioecious species featured by its modified stamens that act as a lever mechanism in pollination. Given sexual dimorphism in floral traits of the species, it is predictable that two sexual morphs differ in their interplay with pollinators and thus in their fitness. In this study, we investigated sex-specific reproduction success and floral adaptation in a population of S. pratensis.

RESULTS

We found that two sexual morphs in S. pratensis distinctly differed in their floral proportions. Female flowers fitted better to the pollinators than hermaphrodites in terms of touching the stigmas when being probed, and hence were more efficient in pollen deposition. Floral traits overall underwent stronger selection in the population, with stigma position and corolla length subject to disruptive selection mediated by different body-sized bumble bees; some selections on floral traits were significantly different in the strength, even opposite in the direction between two morphs. Flower production tended to be under correlational selection with floral structural traits, implying that a large plant with many flowers did not show an advantage in fitness unless its flower construction mechanically matched the pollinators well.

CONCLUSIONS

In conclusion, the pollinator-mediated selection likely played an important role in the evolution and maintenance of sexual dimorphism in the gynodioecious S. pratensis; and sex-divergent mechanical interaction with pollinators served as a critical mechanism by which female individuals were maintained in the population with a female advantage in pollen deposition efficiency (i.e. receiving pollen).

High Yield of Bioactive Abietane Diterpenes in Salvia sclarea Hairy Roots by Overexpressing Cyanobacterial DXS or DXR Genes

Abietane diterpenoids, containing a quinone moiety, are synthesized in the roots of several Salvia species. Promising cytotoxicity and antiproliferative activities have been reported for these compounds in various cell and animal models. We have recently shown that aethiopinone, an o-naphto-quinone diterpene, produced in the roots of different Salvia species, is selectively cytotoxic against the A375 melanoma cell line. To enhance the synthesis of this abietane diterpenoid, we have engineered the plastidial 2-C-methyl-D-erythritol 4-phosphate-derived isoprenoid pathway in Salvia sclarea hairy roots by ectopic expression and plastid targeting of cyanobacterial genes encoding the 1-deoxy-D-xylulose 5-phosphate synthase or 1-deoxy-D-xylulose-5-phosphate reductoisomerase gene, the first two enzymatic steps of the plastidial MEP pathway, from which plant diterpenes primarily derive. Plastid-targeted expression of 1-deoxy-D-xylulose 5-phosphate synthase and 1-deoxy-D-xylulose-5-phosphate reductoisomerase proteins significantly enhanced the yield of aethiopinone by a 3-fold and about 6-fold increase, respectively. The accumulation of other abietane-type diterpenes (ferruginol, salvipisone, and carnosic acid), with interesting antiproliferative activity, was also increased. Compared to our previous data obtained by overexpressing the plant orthologous 1-deoxy-D-xylulose 5-phosphate synthase and 1-deoxy-D-xylulose-5-phosphate reductoisomerase genes in S. sclarea hairy roots, the results presented here confirm that the bacterial 1-deoxy-D-xylulose-5-phosphate reductoisomerase enzyme plays a major role than the DXS enzyme in the biosynthetic pathway of this class of compounds and that its ectopic expression does not conflict with active hairy root growth, resulting in a balanced trade-off between the transgenic hairy root final biomass and the increased content of o-naphto-quinone diterpenes, with interesting biological activities.

Comparative transcriptomic analysis provides insights into the development of a Salvia splendens Ker-Gawler mutant, SX919M

Salvia splendens is a perennial, ornamental herbaceous flower that is widely cultivated as a bedding plant in gardens. The development of novel S. splendens cultivars and investigating the relevant molecular mechanisms are of great significance. In this study, RNA-sequencing and real-time PCR methods were used to analyze the possible molecular mechanism of S. splendens mutant, SX919M. From the wild-type S. splendens 919CK, we firstly selected a natural mutant, SX919M, which displayed multiple branches, clustered spheroids, and radial symmetrical inflorescence with higher numbers of calyces, ovules, stamens, and perianth tubes. Further, the RNA-seq was used to identify the differentially expressed genes (DEGs) in the mutant which included a total of 3568 upregulated and 3290 downregulated unigenes. We further observed that the indole alkaloid biosynthesis pathway showed the highest DEG enrichment, which was supported by a significant increase in the IAA content in mutant SX919M. In addition, we validated three DEGs, namely, CL2200.Contig2_All encoding methyl IAA esterase, CL12462.Contig1_All and CL12462.Contig2_All, which encoded strictosidine synthase, upregulated in mutant SX919M. We selected a novel S. splendens germplasm SX919M with a high ornamental value and determined that the upregulation of IAA biogenesis may be associated with its development.

Phyto-miRNAs-based regulation of metabolites biosynthesis in medicinal plants

Medicinal plants, are known to produce a wide range of plant secondary metabolites (PSMs) applied as insecticides, drugs, dyes and toxins in agriculture, medicine, industry and bio-warfare plus bio-terrorism, respectively. However, production of PSMs is usually in small quantities, so we need to find novel ways to increase both quantity and quality of them. Fortunately, biotechnology suggests several options through which secondary metabolism in plants can be engineered in innovative ways to: 1) over-produce the useful metabolites, 2) down-produce the toxic metabolites, 3) produce the new metabolites. Among the ways, RNA interference (RNAi) technology which involves gene-specific regulation by small non-coding RNAs (sncRNAs) have been recently emerged as a promising tool for plant biotechnologist, not only to decipher the function of plant genes, but also for development of the plants with improved and novel traits through manipulation of both desirable and undesirable genes. Among sncRNAs, miRNAs have been recorded various regulatory roles in plants such as development, signal transduction, response to environmental stresses, metabolism. Certainly, the use of miRNAs in metabolic engineering requires identification of miRNAs involved in metabolites biosynthesis, understanding of the biosynthetic pathways, as well as the identification of key points of the pathways in which the miRNAs have their own effect. Thus, we firstly consider these three issues on metabolic engineering of medicinal plants. Our review shows, application of miRNAs can open a novel perspective to metabolic engineering of medicinal plants.

Phylogeny and staminal evolution of Salvia (Lamiaceae, Nepetoideae) in East Asia

BACKGROUND AND AIMS

Salvia is the largest genus within Lamiaceae, with about 980 species currently recognized. East Asia, with approx. 100 species, is one of the three major biodiversity centres of Salvia. However, relationships within this lineage remain unclear, and the staminal lever mechanism, which may represent a key innovation within the genus, has been understudied. By using six genetic markers and nearly comprehensive taxon sampling, this study attempts to elucidate relationships and examine evolutionary trends of staminal development within the East Asia (EA) Salvia clade.

METHODS

Ninety-one taxa of EA Salvia were sampled and 34 taxa representing all other major lineages of Salvia were included for analysis. Two nuclear [internal transcribed spacer (ITS) and external transcribed spacer (ETS)] and four chloroplast (psbA-trnH, ycf1-rps15, trnL-trnF and rbcL) DNA markers were used for phylogenetic analysis employing maximum parsimony (MP), maximum likelihood (ML) and BEAST, with the latter also used to estimate divergence times.

KEY RESULTS

All Salvia species native to East Asia form a clade, and eight major subclades (A-G) were recognized. Subclade A, comprising two limestone endemics (S. sonchifolia and S. petrophila), is sister to the remainder of EA Salvia. Six distinct stamen types were observed within the EA clade. Stamen type A, with two fully fertile posterior thecae, only occurs in S. sonchifolia and may represent the ancestral stamen type within EA Salvia. Divergence time estimates showed that the crown of EA Salvia began to diversify approx. 17.4 million years ago.

CONCLUSIONS

This study supports the adoption of a broadly defined Salvia and treats EA Salvia as a subgenus, Glutinaria, recognizing eight sections within this subgenus. Stamen type A is ostensibly plesiomorphic within EA Salvia, and the other five types may have been derived from it. Staminal morphology has evolved in parallel within the EA Salvia, and staminal structure alone is inadequate to delimit infrageneric categories.

High-quality assembly of the reference genome for scarlet sage, Salvia splendens, an economically important ornamental plant

Background

Salvia splendens Ker-Gawler, scarlet or tropical sage, is a tender herbaceous perennial widely introduced and seen in public gardens all over the world. With few molecular resources, breeding is still restricted to traditional phenotypic selection, and the genetic mechanisms underlying phenotypic variation remain unknown. Hence, a high-quality reference genome will be very valuable for marker-assisted breeding, genome editing, and molecular genetics.

Findings

We generated 66 Gb and 37 Gb of raw DNA sequences, respectively, from whole-genome sequencing of a largely homozygous scarlet sage inbred line using Pacific Biosciences (PacBio) single-molecule real-time and Illumina HiSeq sequencing platforms. The PacBio de novo assembly yielded a final genome with a scaffold N50 size of 3.12 Mb and a total length of 808 Mb. The repetitive sequences identified accounted for 57.52% of the genome sequence, and  54,008 protein-coding genes were predicted collectively with ab initio and homology-based gene prediction from the masked genome. The divergence time between S. splendens and Salvia miltiorrhiza was estimated at 28.21 million years ago (Mya). Moreover, 3,797 species-specific genes and 1,187 expanded gene families were identified for the scarlet sage genome.

Conclusions

We provide the first genome sequence and gene annotation for the scarlet sage. The availability of these resources will be of great importance for further breeding strategies, genome editing, and comparative genomics among related species.

Salvia castanea Hairy Roots are More Tolerant to Phosphate Deficiency than Salvia miltiorrhiza Hairy Roots Based on the Secondary Metabolism and Antioxidant Defenses

Salvia miltiorrhiza is a well-known traditional Chinese herb which is used to treat heart disease. Salvia castanea is a substitute product for S. miltiorrhiza in the medicinal field. Previous study has shown that phosphate (Pi) deficiency could promote the accumulation of secondary metabolism in herbs, and it has also developed a strategy for saving Pi resources and increasing the yield of active substances in herbs. In the present study, the hairy roots of S. miltiorrhiza and S. castanea were used to identify the Pi deficiency response mechanisms of these two Salvia species. The results showed that Pi deficiency increased the accumulation of specifically secondary metabolites, such as phenolic acids and tanshinones, which were caused by promoting the expression levels of key enzyme genes. In addition, Pi deficiency promoted the antioxidant activity in these two Salvia species. The data demonstrated that Pi deficiency increased the quality of the medicinal material in the plant. The hairy roots of S. castanea were more adaptive to Pi deficiency than those of S. miltiorrhiza in terms of biomass, secondary metabolism, and antioxidant activity. The results of this study provide insights into breeding herbs that are better adapted to Pi deficiency, which could increase the yield of active ingredients in herbs and save Pi resources.

The potential of three different PCR-related approaches for the authentication of mixtures of herbal substances and finished herbal medicinal products

BACKGROUND

Herbal substances and preparations thereof play an important role in healthcare systems worldwide. Due to the variety of these products regarding origin, composition and processing procedures, appropriate methodologies for quality assessment need to be considered. A majority of herbal substances is administered as multicomponent mixtures, especially in the field of Traditional Chinese Medicine and ayurvedic medicine, but also in finished medicinal products. Quality assessment of complex mixtures of herbal substances with conventional methods is challenging. Thus, emphasis of the present work was directed on the development of complementary methods to elucidate the composition of mixtures of herbal substances and finished herbal medicinal products.

HYPOTHESIS/PURPOSE

An indispensable prerequisite for the safe and effective use of herbal medicines is the unequivocal authentication of the medicinal plants used therein. In this context, we investigated the potential of three different PCR-related methods in the characterization and authentication of herbal substances.

METHODS

A multiplex PCR assay and a quantitative PCR (qPCR) assay were established to analyze defined mixtures of the herbal substances Quercus cortex, Juglandis folium, Aristolochiae herba, Matricariae flos and Salviae miltiorrhizae radix et rhizoma and a finished herbal medicinal product. Furthermore, a standard cloning approach using universal primers targeting the ITS region was established in order to allow the investigation of herbal mixtures with unknown content.

RESULTS

The cloning approach had some limitations regarding the detection/recovery of the components in defined mixtures of herbal substances, but the complementary use of two sets of universal primer pairs increased the detection of components out of the mixture. While the multiplex PCR did not retrace all components in the defined mixtures of herbal substances, the established qPCR resulted in simultaneous and specific detection of the five target sequences in all defined mixtures.

CONCLUSION

These data indicate that for authentication purposes, complementary PCR-related methods are highly recommendable for the analysis of herbal mixtures in parallel.

SmJAZ8 acts as a core repressor regulating JA-induced biosynthesis of salvianolic acids and tanshinones in Salvia miltiorrhiza hairy roots

Jasmonates (JAs) are important plant hormones that regulate a variety of plant development and defense processes, including biosynthesis of secondary metabolites. The JASMONATE ZIM DOMAIN (JAZ) proteins act as negative regulators in the JA signaling pathways of plants. We first verified that methyl jasmonate (MeJA) enhanced the accumulation of both salvianolic acids and tanshinones in Salvia miltiorrhiza (Danshen) hairy roots by inducing the expression of their biosynthetic pathway genes. Nine JAZ genes were cloned from Danshen and their expression levels in hairy roots were all increased by treatment with MeJA. When analyzed in detail, however, SmJAZ8 showed the strongest expression in the induced hairy roots. Overexpression or RNAi of SmJAZ8 deregulated or up-regulated the yields of salvianolic acids and tanshinones in the MeJA-induced transgenic hairy roots, respectively, and transcription factors and biosynthetic pathway genes showed an expression pattern that mirrored the production of the compounds. Genetic transformation of SmJAZ8 altered the expression of other SmJAZ genes, suggesting evidence of crosstalk occurring in JAZ-regulated secondary metabolism. Furthermore, the transcriptome analysis revealed a primary-secondary metabolism balance regulated by SmJAZ8. Altogether, we propose a novel role for SmJAZ8 as a negative feedback loop controller in the JA-induced biosynthesis of salvianolic acids and tanshinones.

Screening of Hallucinogenic Compounds and Genomic Characterisation of 40 Anatolian Salvia Species

INTRODUCTION

Salvia, an important and widely available member of Lamiaceae family. Although comparative analysis on secondary metabolites in several Salvia species from Turkey has been reported, their hallucinogenic chemicals have not been screened thoroughly.

OBJECTIVE

This study provides LC-MS/MS analysis of 40 Salvia species for screening their psychoactive constituents of salvinorin A and salvinorin B. 5S-rRNA gene non-coding region of Salvia plants was sequenced, aligned and compared with that sequence of Salvia divinorum plant.

METHODOLOGY

Targeted molecules of salvinorin A and salvinorin B were quantified, using LC-MS/MS, from all aerial parts of 40 Salvia species, collected from different parts of Turkey. Regions of 5S-rRNA gene from different species were amplified by polymerase chain reaction and DNA sequences were aligned with Salvia divinorum DNA sequences.

RESULTS

Very few of the Salvia species (S. recognita, S. cryptantha and S. glutinosa) contained relatively high levels of salvinorin A (212.86 ± 20.46 μg/g, 51.50 ± 4.95 μg/g and 38.92 ± 3.74 μg/g, respectively). Salvinorin B was also found in Salvia species of S. potentillifolia, S. adenocaulon and S. cryptantha as 2351.99 ± 232.22 μg/g, 768.78 ± 75.90 μg/g and 402.24 ± 39.71 μg/g, respectively. The sequences of 5S-rRNA gene of 40 different Salvia species were presented and it was found that none of the Salvia species in Turkey had similar DNA sequence to Salvia divinorum plant.

CONCLUSION

This is the first report of screening 40 Salvia species in Turkey according to their psychoactive constituents, salvinorin A and salvinorin B and their genomic structures. It is possible that some of these Salvia species may exhibit some psycho activity. Thus, they need to be screened further. Copyright © 2017 John Wiley & Sons, Ltd.

Biosynthesis of the psychotropic plant diterpene salvinorin A: Discovery and characterization of the Salvia divinorum clerodienyl diphosphate synthase

Salvia divinorum commonly known as diviner's sage, is an ethnomedicinal plant of the mint family (Lamiaceae). Salvia divinorum is rich in clerodane-type diterpenoids, which accumulate predominantly in leaf glandular trichomes. The main bioactive metabolite, salvinorin A, is the first non-nitrogenous natural compound known to function as an opioid-receptor agonist, and is undergoing clinical trials for potential use in treating neuropsychiatric diseases and drug addictions. We report here the discovery and functional characterization of two S. divinorum diterpene synthases (diTPSs), the ent-copalyl diphosphate (ent-CPP) synthase SdCPS1, and the clerodienyl diphosphate (CLPP) synthase SdCPS2. Mining of leaf- and trichome-specific transcriptomes revealed five diTPSs, two of which are class II diTPSs (SdCPS1-2) and three are class I enzymes (SdKSL1-3). Of the class II diTPSs, transient expression in Nicotiana benthamiana identified SdCPS1 as an ent-CPP synthase, which is prevalent in roots and, together with SdKSL1, exhibits a possible dual role in general and specialized metabolism. In vivo co-expression and in vitro assays combined with nuclear magnetic resonance (NMR) analysis identified SdCPS2 as a CLPP synthase. A role of SdCPS2 in catalyzing the committed step in salvinorin A biosynthesis is supported by its biochemical function, trichome-specific expression and absence of additional class II diTPSs in S. divinorum. Structure-guided mutagenesis revealed four catalytic residues that enabled the re-programming of SdCPS2 activity to afford four distinct products, thus advancing our understanding of how neo-functionalization events have shaped the array of different class II diTPS functions in plants, and may promote synthetic biology platforms for a broader spectrum of diterpenoid bioproducts.

Environmental gradients shape the genetic structure of two medicinal Salvia species in Jordan

Environmental gradients, and particularly climatic variables, exert a strong influence on plant distribution and, potentially, population genetic diversity and differentiation. Differences in water availability can cause among-population variation in ecological processes and can thus interrupt populations' connectivity and isolate them environmentally. The present study examines the effect of environmental heterogeneity on plant populations due to environmental isolation unrelated to geographic distance. Using AFLP markers, we analyzed genetic diversity and differentiation among 12 Salvia spinosa populations and 13 Salvia syriaca populations from three phytogeographical regions (Mediterranean, Irano-Turanian and Saharo-Arabian) representing the extent of the species' geographic range in Jordan. Differences in geographic location and climate were considered in the analyses. For both species, flowering phenology varied among populations and regions. Irano-Turanian and Saharo-Arabian populations had higher genetic diversity than Mediterranean populations, and genetic diversity increased significantly with increasing temperature. Genetic diversity in Salvia syriaca was affected by population size, while genetic diversity responded to drought in S. spinosa. For both species, high levels of genetic differentiation were found as well as two well-supported phytogeographical groups of populations, with Mediterranean populations clustering in one group and the Irano-Turanian and Saharo-Arabian populations in another. Genetic distance was significantly correlated to environmental distance, but not to geographic distance. Our data indicate that populations from moist vs. arid environments are environmentally isolated, where environmental gradients affect their flowering phenology, limit gene flow and shape their genetic structure. We conclude that environmental heterogeneity may act as driver for the observed variation in genetic diversity.

Increasing the synthesis of bioactive abietane diterpenes in Salvia sclarea hairy roots by elicited transcriptional reprogramming

Transcriptional activation of genes belonging to the plastidial MEP-derived isoprenoid pathway by elicitation with methyl jasmonate and coronatine enhanced the content of bioactive abietane diterpenes in Salvia sclarea hairy roots. We have shown that aethiopinone, an abietane diterpene synthesized in Salvia sclarea roots is cytotoxic and induces apoptosis in human melanoma cells. To develop a production platform for this compound and other abietane diterpenes, hairy root technology was combined with the elicitation of methyl jasmonate (MeJA) or the phytotoxin coronatine (Cor). Both MeJA and Cor induced a significant accumulation of aethiopinone, but prolonged exposure to MeJA irremediably caused inhibition of hairy root growth, which was unaffected by Cor treatment. Considering together the fold increase in aethiopinone content and the final hairy root biomass, the best combination was a Cor treatment for 28 days, which allowed to obtain up to 105.34 ± 2.30 mg L^-1 of this compound to be obtained, corresponding to a 24-fold increase above the basal content in untreated hairy roots. MeJA or Cor elicitation also enhanced the synthesis of other bioactive abietane-quinone diterpenes. The elicitor-dependent steering effect was due to a coordinated transcriptional activation of several biosynthetic genes belonging to the plastidial MEP-derived isoprenoid pathway. High correlations between aethiopinone content and MeJA or Cor-elicited level of gene transcripts were found for DXS2 (r ² = 0.99), DXR (r ² = 0.99), and GGPPS (r ² = 0.98), encoding enzymes acting upstream of GGPP, the common precursor of diterpenes and other plastidial-derived terpenes, as well as CPPS (r ² = 0.99), encoding the enzyme involved in the first cyclization steps leading to copalyl-diphosphate, the precursor of abietane-like diterpenes. These results point to these genes as possible targets of metabolic engineering approaches to establish a more efficient production platform for such promising anti-proliferative plant-derived compounds.

A (-)-kolavenyl diphosphate synthase catalyzes the first step of salvinorin A biosynthesis in Salvia divinorum

Salvia divinorum (Lamiaceae) is an annual herb used by indigenous cultures of Mexico for medicinal and ritual purposes. The biosynthesis of salvinorin A, its major bioactive neo-clerodane diterpenoid, remains virtually unknown. This investigation aimed to identify the enzyme that catalyzes the first reaction of salvinorin A biosynthesis, the formation of (-)-kolavenyl diphosphate [(-)-KPP], which is subsequently dephosphorylated to afford (-)-kolavenol. Peltate glandular trichomes were identified as the major and perhaps exclusive site of salvinorin accumulation in S. divinorum. The trichome-specific transcriptome was used to identify candidate diterpene synthases (diTPSs). In vitro and in planta characterization of a class II diTPS designated as SdKPS confirmed its activity as (-)-KPP synthase and its involvement in salvinorin A biosynthesis. Mutation of a phenylalanine into histidine in the active site of SdKPS completely converts the product from (-)-KPP into ent-copalyl diphosphate. Structural elements were identified that mediate the natural formation of the neo-clerodane backbone by this enzyme and suggest how SdKPS and other diTPSs may have evolved from ent-copalyl diphosphate synthase.

[Not Available]

Nuruozak (Salvia leriifolia Benth), is a perennial herbaceous plant that is endemic to Iran and has recently been introduced as a medicinal plant. Artificial polyploidy is an efficient method to increase the production of secondary metabolites and can result in a whole spectrum of genetic, molecular and physiological modifications. In order to produce an autotetraploid population of nuruozak, various concentrations of colchicine (0.00, 0.05, 0.10, 0.20 or 0.50 % w/v) were applied to the seeds and shoot apical meristems of young seedlings at the fourth leaf-stage. Microscopic studies, flow cytometry analysis and chromosome counting were conducted to select tetraploid nuruozak plants. Furthermore, the effects of ploidy level on the essential oil content and composition and biomass production of nuruozak plants, as well as selected structural and physiological characteristics were studied. Based on the number of the obtained tetraploids, treatment of shoot apical meristems was more efficient than seed treatment. Structural and phytochemical characteristics, chlorophyll content and photosynthetic rate were affected by the increase in ploidy level. In addition to the higher potential in biomass production, tetraploid plants produced eight new compounds which were absent in diploids.

Selective in vitro and in silico butyrylcholinesterase inhibitory activity of diterpenes and rosmarinic acid isolated from Perovskia atriplicifolia Benth. and Salvia glutinosa L

Cholinesterase inhibition is one of the most treatment strategies against Alzheimer's disease (AD) where metal accumulation is also strongly associated with pathology of the disease. In the current study, we assessed inhibitory effect against acetyl- (AChE) and butyrylcholinesterase (BChE) and metal-chelating capacity of twelve diterpenes: arucadiol, miltirone, tanshinone IIa, 1-oxomiltirone, cryptotanshinone, 1,2-didehydromiltirone, 1,2-didehydrotanshinone IIa, 1β-hydroxycryptotanshinone, 15,16-dihydrotanshinone, tanshinone I, isotanshinone II, 1(S)-hydroxytanshinone IIa, and rosmarinic acid, isolated from Perovskia atriplicifolia and Salvia glutinosa. The compounds were tested at 10 μg/mL using ELISA microtiter assays against AChE and BChE. QSAR and molecular docking studies have been also performed on the active compounds. All of the compounds showed higher [e.g., IC50 = 1.12 ± 0.07 μg/mL for 1,2-didehydromiltirone, IC50 = 1.15 ± 0.07 μg/mL for cryptotanshinone, IC50 = 1.20 ± 0.03 μg/mL for arucadiol, etc.)] or closer [1,2-didehydrotanshinone IIa (IC50 = 5.98 ± 0.49 μg/mL) and 1(S)-hydroxytanshinone IIa (IC50 = 5.71 ± 0.27 μg/mL)] inhibition against BChE as compared to that of galanthamine (IC50 = 12.56 ± 0.37 μg/mL), whereas only 15,16-dihydrotanshinone moderately inhibited AChE (65.17 ± 1.39%). 1,2-Didehydrotanshinone IIa (48.94 ± 0.26%) and 1(S)-hydroxytanshinone IIa (47.18 ± 5.10%) possessed the highest metal-chelation capacity. The present study affords an evidence for the fact that selective BChE inhibitors should be further investigated as promising candidate molecules for AD therapy.

Establishment of Salvia castanea Diels f. tomentosa Stib. hairy root cultures and the promotion of tanshinone accumulation and gene expression with Ag⁺, methyl jasmonate, and yeast extract elicitation

Salvia castanea Diels f. tomentosa Stib. is an endemic medicinal plant distributed in China, and the notably high content of tanshinone IIA in the root is proven effective for the therapy of heart diseases. Hairy root induction of this Salvia species was inoculated with Agrobacterium rhizogenes strain ATCC 15834. Transformed hairy root was cultured in 6,7-V liquid medium for growth kinetics assessment and elicitation. An S curve was present in the hairy root cultures based on the fresh and dry weights with an interval of 3 days. An optimum concentration of the applied elicitors (15 μM Ag(+), 200 μM methyl jasmonate, and 200 mg l(-1) yeast extract elicitor) benefitted both the growth status and tanshinone accumulation in the hairy root cultures. Tanshinone IIA contents were mostly stimulated 1.8-fold and 1.99-fold compared with the control by Ag(+) and methyl jasmonate elicitation, respectively. Yeast extract dramatically enhanced dry mass accumulation, while it promoted cryptotanshinone content of 2.84 ± 0.33 mg g(-1) dry weight at most in the hairy root cultures. Selected elicitors diversely influenced tanshinone accumulation in the time courses of hairy root cultures within 7 days. Furthermore, transcripts of selected genes in the tanshinone biosynthetic pathway were remarkably upregulated with elicitation. Yeast extract elicitor heightened 13.9-fold of isopentenyl diphosphate isomerase expression level at 12 h, while it increased 16.7-fold of geranylgeranyl diphosphate synthase transcript at 24 h compared with that of the control, which was more effective than Ag(+) and methyl jasmonate. This study provided a convenient hairy root culture system of S. castanea Diels f. tomentosa Stib. for tanshinone production for the first time.

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.

Exploring triacylglycerol biosynthetic pathway in developing seeds of Chia (Salvia hispanica L.): a transcriptomic approach

Chia (Salvia hispanica L.), a member of the mint family (Lamiaceae), is a rediscovered crop with great importance in health and nutrition and is also the highest known terrestrial plant source of heart-healthy omega-3 fatty acid, alpha linolenic acid (ALA). At present, there is no public genomic information or database available for this crop, hindering research on its genetic improvement through genomics-assisted breeding programs. The first comprehensive analysis of the global transcriptome profile of developing Salvia hispanica L. seeds, with special reference to lipid biosynthesis is presented in this study. RNA from five different stages of seed development was extracted and sequenced separately using the Illumina GAIIx platform. De novo assembly of processed reads in the pooled transcriptome using Trinity yielded 76,014 transcripts. The total transcript length was 66,944,462 bases (66.9 Mb), with an average length of approximately 880 bases. In the molecular functions category of Gene Ontology (GO) terms, ATP binding and nucleotide binding were found to be the most abundant and in the biological processes category, the metabolic process and the regulation of transcription-DNA-dependent and oxidation-reduction process were abundant. From the EuKaryotic Orthologous Groups of proteins (KOG) classification, the major category was “Metabolism” (31.97%), of which the most prominent class was ‘carbohydrate metabolism and transport’ (5.81% of total KOG classifications) followed by ‘secondary metabolite biosynthesis transport and catabolism’ (5.34%) and ‘lipid metabolism’ (4.57%). A majority of the candidate genes involved in lipid biosynthesis and oil accumulation were identified. Furthermore, 5596 simple sequence repeats (SSRs) were identified. The transcriptome data was further validated through confirmative PCR and qRT-PCR for select lipid genes. Our study provides insight into the complex transcriptome and will contribute to further genome-wide research and understanding of chia. The identified novel UniGenes will facilitate gene discovery and creation of genomic resource for this crop.

Genetic variability and population structure of Salvia lachnostachys: implications for breeding and conservation programs

The genetic diversity and population structure of Salvia lachnostachys Benth were assessed. Inter Simple Sequence Repeat (ISSR) molecular markers were used to investigate the restricted distribution of S. lachnostachys in Parana State, Brazil. Leaves of 73 individuals representing three populations were collected. DNA was extracted and submitted to PCR-ISSR amplification with nine tested primers. Genetic diversity parameters were evaluated. Our analysis indicated 95.6% polymorphic loci (stress value 0.02) with a 0.79 average Simpson's index. The Nei-Li distance dendrogram and principal component analysis largely recovered the geographical origin of each sample. Four major clusters were recognized representing each collected population. Nei's gene diversity and Shannon's information index were 0.25 and 0.40 respectively. As is typical for outcrossing herbs, the majority of genetic variation occurred at the population level (81.76%). A high gene flow (Nm = 2.48) was observed with a correspondingly low fixation index. These values were generally similar to previous studies on congeneric species. The results of principal coordinate analysis (PCA) and of arithmetic average (UPGMA) were consistent and all three populations appear distinct as in STRUCTURE analysis. In addition, this analysis indicated a majority intrapopulation genetic variation. Despite the human pressure on natural populations our study found high levels of genetic diversity for S. lachnostachys. This was the first molecular assessment for this endemic species with medicinal proprieties and the results can guide for subsequent bioprospection, breeding programs or conservation actions.

Why Africa matters: evolution of Old World Salvia (Lamiaceae) in Africa

BACKGROUND AND AIMS

Salvia is the largest genus in Lamiaceae and it has recently been found to be non-monophyletic. Molecular data on Old World Salvia are largely lacking. In this study, we present data concerning Salvia in Africa. The focus is on the colonization of the continent, character evolution and the switch of pollination systems in the genus.

METHODS

Maximum likelihood and Bayesian inference were used for phylogenetic reconstruction. Analyses were based on two nuclear markers [internal transcribed spacer (ITS) and external transcribed spacer (ETS)] and one plastid marker (rpl32-trnL). Sequence data were generated for 41 of the 62 African taxa (66 %). Mesquite was used to reconstruct ancestral character states for distribution, life form, calyx shape, stamen type and pollination syndrome.

KEY RESULTS

Salvia in Africa is non-monophyletic. Each of the five major regions in Africa, except Madagascar, was colonized at least twice, and floristic links between North African, south-west Asian and European species are strongly supported. The large radiation in Sub-Saharan Africa (23 species) can be traced back to dispersal from North Africa via East Africa to the Cape Region. Adaptation to bird pollination in southern Africa and Madagascar reflects parallel evolution.

CONCLUSIONS

The phenotypic diversity in African Salvia is associated with repeated introductions to the continent. Many important evolutionary processes, such as colonization, adaptation, parallelism and character transformation, are reflected in this comparatively small group. The data presented in this study can help to understand the evolution of Salvia sensu lato and other large genera.

De novo assembly and annotation of Salvia splendens transcriptome using the Illumina platform

BACKGROUND

As an important perennial herbaceous flower, Salvia splendens possesses high ornamental value. Understanding its branching processes may help scientists select the best plant type. Although Salvia splendens is a frequently-used horticultural flower, only limited transcriptomic or genomic research is available in public databases. In the present study, we, for the first time, constructed a comprehensive dataset for Salvia splendens through de novo high-throughput transcriptome sequencing.

METHODOLOGY/PRINCIPAL FINDINGS

We performed de novo transcriptome sequencing on two different branching type plants (Strain 35 and Cailinghong) using the Illumina paired-end sequencing technology. For Strain 35, a total of 16,488,829 reads were generated and assembled into 38,498 unigenes, with a mean length of approximately 779 bp. For Cailinghong, 16,464,713 reads were generated and assembled into 34,302 unigenes, with a mean length of approximately 812 bp. Moreover, a total of 49,310 unigenes for Salvia splendens were identified, among them 33,925 (68.80%) were annotated in the non-redundant NCBI database, 25,371 (51.45%) were annotated in the Swiss-Prot database, while 24,888 (50.47%) and 9,896 (20.07%) unigenes were assigned to gene ontology categories and clusters of orthologous groups, respectively. Using the Kyoto Encyclopedia of Genes and Genomes pathway database, we identified 134 differently expressed unigenes between Strain 35 and Cailinghong, and then these unigenes were mapped to 79 pathways. In addition, we detected 2,453 simple sequence repeats (SSRs).

CONCLUSIONS

We obtained a comprehensive transcriptomic information from this work and provided a valuable resource of transcript sequences of Salvia splendens in public databases. Moreover, some candidate genes potentially involved in branching were identified. Furthermore, numerous obtained SSRs might contribute to marker-assisted selection. These data could be further utilized in functional genomics studies on Salvia splendens.

[Identification of Salvia shandongensis new species based on sequences of the plastid psbA-trnH intergenic region]

To identify Salvia shandongensis and its relatives at molecular level, the psbA-trnH intergenic region of three species including Salvia shandongensis, Salvia miltiorrhiza and S. miltiorrhiza f. alba were amplified and sequenced. Sequences were assembled with CodonCode Aligner. The K2P genetic distances between Salvia shandongensis and its relatives were calculated and UPGMA tree was performed by MEGA5.0. The results indicated that the lengths of psbA-trnH regions of Salvia shandongensis were about 391 bp, while the lengths of psbA-trnH regions of Salvia miltiorrhiza and S. miltiorrhiza f. alba were about 386 bp. The psbA-trnH sequences showed considerable variations between species and thus were revealed as a promising candidate for barcoding of Salvia shandongensis and its relatives. The intra-specific genetic distances of Salvia shandongensis were 0, while the intra-specific genetic distances of Salvia miltiorrhiza and S. miltiorrhiza f. alba were 0.002 and 0.001 respectively. Additionally, the genetic distance of Salvia shandongensis and Salvia miltiorrhiza ranged from 0.034 to 0.04, and the genetic distance of Salvia shandongensis and S. miltiorrhiza f. alba ranged from 0.005 to 0.008, the intra-specific genetic distances of Salvia shandongensis were much smaller than that of Salvia miltiorrhiza and S. miltiorrhiza f. alba; clustering results showed that there were obvious differences between Salvia shandongensis, Salvia miltiorrhiza and S. miltiorrhiza f. alba, which was consistent with morphological characteristics. This study not only firstly provides the scientific basis for establishing the taxonomy position in molecular level and revealing their genetic relationships of S. shandongensis, S. miltiorrhiza and S. miltiorrhiza f. alba; but also provides DNA molecular identification scientific basis for the development of new medicinal plant resources of Salvia shandongensis. Our results suggest that the psbA-trnH intergenic spacer region can be used as a barcoding to identify Salvia shandongensis, Salvia miltiorrhiza and S. miltiorrhiza f. alba.

[Engineering Saccharomyces cerevisiae for sclareol production]

Sclareol is a member of labdane type diterpenes mostly used as fragrance ingredient. To enable microbial production of sclareol, synthetic pathways were constructed by incorporating labdenediol diphosphate synthase (LPPS) and terpene synthase (TPS) of the plant Salvia sclarea into Saccharomyces cerevisiae. It was found that sclareol production could be benefited by overexpression of key enzyme for precursor biosynthesis, construction of fusion protein for substrate channeling, and removal of signal peptides from LPPS and TPS. Under optimal shake flask culture conditions, strain S6 produced 8.96 mg/L sclareol. These results provided useful information for development of heterologous hosts for production of terpenoids.