Dioscorea Composita Research Articles

Comparative transcriptomic and metabolomic analyses reveal key regulatory gene for methyl jasmonate-induced steroidal saponins synthesis in Dioscorea composita

Dioscorea composita (D. composita) is a perennial herb with abundant steroidal saponins that have gained worldwide attention for their remarkable efficacy in cardiovascular diseases. However, few studies have been worked on the regulatory network of steroidal saponins biosynthesis under phytohormone induced. In this study, we combined the transcriptome and metabolome analysis to reveal the variation of diosgenin and steroidal saponins in transcriptional and metabolism levels under methyl-jasmonate (MeJA) treatment. Although the application of MeJA indeed significantly increased the accumulation of diosgenin of D. composita, different types of steroidal saponins exhibited different accumulation patterns. Consistently, the expression levels of UDP-glycosyltransferases and Cytochrome P450 monooxygenases genes that highly related to the accumulation of steroidal saponins were either up- or down-regulated. Correlation analyses of transcription factors (TFs)-steroidal saponins and structural genes-TFs were further to identified the TFs potentially involved in the regulation of steroidal saponins biosynthesis. Silencing of DcWRKY11 in Dioscorea composita decreases the accumulation of steroidal saponins by regulating the expression steroidal saponins synthesis genes, suggesting that DcWRKY11 is a positive regulator in the regulation of steroidal saponins biosynthesis. Our findings take a deeper understanding of the regulatory network of MeJA-mediated steroidal saponins biosynthesis in D. composita.

Eco-Geography of Dioscorea composita (Hemsl.) in México and Central America under the Influence of Climate Change

Dioscorea composita is a plant with historical recognition for the production of secondary metabolites of pharmaceutical importance, including diosgenin, and with great nutritional and ethnobotanical value in its center of origin (México and Central America). Furthermore, it is considered a promising therapeutic agent against cancer. Currently, México is one of the two most important countries producing this yam; however, climate change is altering the environmental conditions of its natural habits, threatening its preservation and productivity. This is why this research was focused on characterizing the eco-geography of D. composita and predicting its potential geographic distribution under climate change scenarios in México-Central America. A collection of 408 geo-referenced accessions was used to determine its climatic adaptation, ecological descriptors, and the current and future potential geographic distribution, which was modeled with the MaxEnt model through the Kuenm R-package. For future climate scenarios, an ensemble of the GCMs HadGEM-ES and CCSM4 was used. Results showed that D. composita adapts to warm and humid and very humid agro-climates and, the most contributing variables for its presence are annual and seasonal moisture availability indices, the seasonal photoperiod, annual thermal range, and Bio14 and Bio11. The current potential distribution (692,123 km2) of D. composita might decrease by the year 2050 RCP4.5 (365,680 km2) and might increase by 2050 under the scenario RCP8.5 (763,589 km2), showing this plant could be a good crop option for this climate change scenario. The findings obtained provide valuable information that will allow for the effective utilization of this plant, both in terms of developing new pharmaceutical products and implementing appropriate conservation strategies.

Dioscorea composita WRKY5 positively regulates AtSOD1 and AtABF2 to enhance drought and salt tolerances.

DcWRKY5 increases the antioxidant enzyme activity and proline accumulation, oppositely, reduces the accumulation of ROS and MDA, through directly activating the genes expression, finally enhances the salt and drought tolerance. Drought and salinity are two main environmental factors that limit the large-scale cultivation of the medicinal plant Dioscorea composita (D. composita). WRKY transcription factors (TFs) play vital roles in regulating drought and salt tolerance in plants. Nevertheless, the molecular mechanism of WRKY TF mediates drought and salt resistance of D. composita remains largely unknown. Here, we isolated and characterized a WRKY TF from D. composita, namely DcWRKY5, which was localized to the nucleus and bound to the W-box cis-acting elements. Expression pattern analysis showed that it was highly expressed in root and significantly up-regulated in the presence of salt, polyethylene glycol-6000 (PEG-6000) and abscisic acid (ABA). Heterologous expression of DcWRKY5 increased salt and drought tolerance in Arabidopsis, but was insensitive to ABA. In addition, compared with the wild type, the DcWRKY5 overexpressing transgenic lines had more proline, higher antioxidant enzyme (POD, SOD, and CAT) activities, less reactive oxygen species (ROS) and malondialdehyde (MDA). Correspondingly, the overexpression of DcWRKY5 modulated the expression of genes related to salt and drought stresses, such as AtSS1, AtP5CS1, AtCAT, AtSOD1, AtRD22, and AtABF2. Dual luciferase assay and Y1H were further confirmed that DcWRKY5 activate the promoter of AtSOD1 and AtABF2 through directly binding to the enrichment region of the W-box cis-acting elements. These results suggest that DcWRKY5 is a positive regulator of the drought and salt tolerance in D. composita and has potential applications in transgenic breeding.

Dioscorea composita WRKY12 is involved in the regulation of salt tolerance by directly activating the promoter of AtRCI2A

Dioscorea composita (D. composita) is an important medicinal plant worldwide with high economic value. However, its large-scale cultivation was limited by soil salinization. Identification of genes and their mechanisms of action in response to salt stress are critically important. In the present study, we isolated a classical WRKY transcription factor from D. composita, namely DcWRKY12, and analyzed its function in salt tolerance. Expression pattern analysis showed DcWRKY12 is mainly expressed in roots and significantly induced by NaCl, polyethylene glycol-6000 (PEG-6000), and abscisic acid (ABA). Phenotypic and physiological analyses revealed that heterologous expression of DcWRKY12 enhanced salt and osmotic stress tolerance by increasing antioxidant enzyme activity, osmoregulatory substance content, maintaining relative water content and ion homeostasis, decreasing reactive oxygen species and malondialdehyde content. Correspondingly, the overexpression of DcWRKY12 modulated the expression of salt stress-responsive and ion transport-related genes. Dual luciferase assay and Y1H were further confirmed that DcWRKY12 activates the promoter of AtRCI2A through directly binding to the specific W-box cis-acting elements. These results suggest that DcWRKY12 is a positive regulator of salt tolerance in D. composita and has potential applications in salt stress.

Geographic distribution and uses of species of the genus Dioscorea

Species of the genus Dioscorea are widely distributed throughout the world. It is a resource used in different countries because theyproduce tubers that offer numerous benefits for human health due to their diosgenin content, a compound that is used as: anti-inflammatory, androgenic, estrogenic and in the preparation of contraceptive drugs; It is also mentioned that these compounds havecytotoxic, antitumor, antifungal, immunoregulatory, hypoglycemic and cardiovascular properties, they are also used for theprevention and treatment of degenerative diseases. Species such as Dioscorea bulbifera, Dioscorea cayenensis, Dioscorea colletii,Dioscorea deltoidea, Dioscorea futschauensis, Dioscorea nipponica, Dioscorea panthaica, Dioscorea parviflora, Dioscoreapolygonoides, Dioscorea pseudojaponica, Dioscorea spongiosa, Dioscorea villosa, Dioscorea composita, Dioscorea zingiberensis,produce a higher concentration of diosgenin. The tubers and roots of this group are part of the oldest foods consumed by humans,given their high nutritional, ecological and economic level. In many tropical countries, the use of various tubers and roots of thegenus Dioscorea play a very important role as a main source of energy and essential nutrients at low cost, they are also used asfodder for livestock and a source of income. This plant are rich in starch, vitamins, minerals and lipids, and have the potential tofight hunger in third world countries. Currently there is little or no knowledge in Mexico on how to cultivate these species.

Effect of Fertilizers on the Sapogenin Yields of Dioscorea composita in Puerto Rico

Seedlings of Dioscorea composita were treated with various combinations of ammonium sulfate, superphosphate, and potassium sulfate over a 3-year period. The tubers of the resulting plantings were tested for sapogenin content. Complete fertilization increased the sapogenin yields significantly as compared with an untreated control. Incomplete combinations or single-nutrient treatments did not significantly increase yields and, in some cases, decreased them. Yield increases were associated with increased fresh and dry weight. Although no significant effects of fertility on percentage of sapogenin were found, tubers in unfertilized plots contained the highest sapogenin in percentage.

Dioscorea composita WRKY3 positively regulates salt-stress tolerance in transgenic Arabidopsis thaliana

Dioscorea composita (D. composita) is a perennial dioecious herb with strong biotic and abiotic stress tolerance. However, what roles WRKY transcription factors might play in regulating abiotic stress responses in this medicinal plant is unknown. Here, we isolated DcWRKY3 from D. composita and analyzed its role in stress tolerance. DcWRKY3 is a group I WRKY transcription factor that localized to the nucleus and specifically bound to the W-box cis-elements, but lacked transcriptional activation activity in yeast cells. The expression of DcWRKY3 was strongly affected by salt stress. The heterologous expression of DcWRKY3 strongly enhanced the seed germination rate and root length of Arabidopsis thaliana under salt stress. The DcWRKY3-expressing transgenic lines (DcWRKY3-OEs) also showed higher proline content and antioxidant enzyme activity but lower malondialdehyde and reactive oxygen (ROS) levels compared with the wild type. Moreover, these plants showed upregulated expression of genes related to the salt-stress response and ROS clearance. These findings indicate that DcWRKY3 plays a positive role in the salt-stress response by improving the ROS scavenging ability and maintaining the balance of osmotic pressure in plants. Further studies showed that DcWRKY3 binds to the promoter of AtP5CS1, but not AtSOD and AtRD22, suggesting that DcWRKY3 improves salt tolerance in plants by directly or indirectly regulating the expression of downstream genes. This functional characterization of DcWRKY3 provides new insight into the molecular mechanism underlying the response of D. composita to salt stress.

The Effect of Various Herbicides on Growth of Dioscorea composita (Hemsl.) Under Greenhouse Conditions

A series of tests was conducted under greenhouse conditions to determine the relative usefulness of various herbicides for control of weeds in cortisone yam (Dioscorea composita Hemsl.) plantings. Monuron, Diuron, Neburon, Atrazine, Simazine and Prometryne each were applied at three different rates. Diuron and Monuron were found to be the most toxic of the substituted ureas. The most injurious of the triazines was Atrazine. Simazine, although somewhat toxic, was less so than than Atrazine. No evidence of Prometryne poisoning could be detected. As expected, the number and weight of weeds were significantly lower in the test plots of plants treated with herbicides.

Enhanced co-generation of cellulosic ethanol and methane with the starch/sugar-rich waste mixtures and Tween 80 in fed-batch mode

BackgroundThe mixed-feedstock fermentation is a promising approach to enhancing the co-generation of cellulosic ethanol and methane from sugarcane bagasse (SCB) and molasses. However, the unmatched supply of the SCB and molasses remains a main obstacle built upon binary feedstock. Here, we propose a cellulose–starch–sugar ternary waste combinatory approach to overcome this bottleneck by integrating the starch-rich waste of Dioscorea composita Hemls. extracted residue (DER) in mixed fermentation.ResultsThe substrates of the pretreated SCB, DER and molasses with varying ratios were conducted at a relatively low solids loading of 12%, and the optimal mixture ratio of 1:0.5:0.5 for the pretreated SCB/DER/molasses was determined by evaluating the ethanol concentration and yield. Nevertheless, it was found that the ethanol yield decreased from 79.19 ± 0.20 to 62.31 ± 0.61% when the solids loading increased from 12 to 44% in batch modes, regardless of the fact that the co-fermentation of three-component feedstock was performed under the optimal condition defined above. Hence, different fermentation processes such as fed-batch and fed-batch + Tween 80 were implemented to further improve the ethanol concentration and yield at higher solids loading ranging between 36 and 44%. The highest ethanol concentration of 91.82 ± 0.86 g/L (69.33 ± 0.46% of theoretical yield) was obtained with fed-batch + Tween 80 mode during the simultaneous saccharification and fermentation at a high solids loading of 44%. Moreover, after the ethanol recovery, the remaining stillage was digested for biomethane production and finally yielded 320.72 ± 6.98 mL/g of volatile solids.ConclusionsIntegrated DER into the combination of SCB and molasses would be beneficial for ethanol production. The co-generation of bioethanol and biomethane by mixed cellulose–starch–sugar waste turns out to be a sustainable solution to improve the overall efficacy in biorefinery.

Biorefinery of Dioscorea composita Hemsl with ferric chloride for saponins conversion to diosgenin and recycling the waste to biomethane

Diosgenin is an important raw material for the synthesis of steroid hormone drug and largely required in the pharmaceutical industry. In this study, a novel process for biorefinery of Dioscorea composita Hemsl (DCH) with ferric chloride was developed to investigate the conversion of saponins to diosgenin. Furthermore, the waste, including sugary wastewater and starch residue, as recyclable biomass resources after diosgenin extraction was devoted to biomethane. Consequently, the highest yield of diosgenin (3.02%) was obtained using ethanol/water/petroleum ether (15/16/20, v/v/v) with a total volume of 255 mL containing 80 mL 5.0 g/L ferric chloride aqueous solution at 150 °C for 2 h. The yield extracted with FeCl3 was 16.6% higher than the traditional sulfuric acid hydrolysis method and was even 2.3 times more than the biphasic sulfuric acid hydrolysis method. Similarly, without consuming sulfuric acid, the yield was 79.76% higher than the control method. After fermentation, a maximum biomethane yield of 310.5 mL/g COD (chemical oxygen demand) was achieved from wastewater and the decomposition efficiency reached 91.1% with an initial COD concentration of 10,800 mg/L decreasing to 960 mg/L. The final biomethane productivity of waste residues was 278.8 mL/g VS and the VS degradation efficiency was 95.8% after a week. Therefore, the novel method with FeCl3-catalyzed acidolysis to produce diosgenin and biomethane may be an alternative much cleaner approach to better utilize dioscorea resources.

Ethanol production from mixtures of sugarcane bagasse and Dioscorea composita extracted residue with high solid loading

Various mixing ratios of alkali pretreated sugarcane bagasse and starch-rich waste Dioscorea composita hemls extracted residue (DER) were evaluated via simultaneous saccharification and fermentation (SSF) with 12% (w/w) solid loading, and the mixture ratio of 1:1 achieved the highest ethanol concentration and yield. When the solid loading was increased from 12% to 32%, the ethanol concentration was increased to 72.04 g/L, whereas the ethanol yield was reduced from 84.40% to 73.71%. With batch feeding and the addition of 0.1% (w/v) Tween 80, the final ethanol concentration and yield of SSF at 34% loading were 82.83 g/L and 77.22%, respectively. Due to the integration with existing starch-based ethanol industry, the co-fermentation is expected to be a competitive alternative form for cellulosic ethanol production.

Catalytic conversion of raw Dioscorea composita biomass to 5-hydroxymethylfurfural using a combination of metal chlorides in N,N-dimethylacetamide solvent containing lithium chloride

We synthesized 5-hydroxymethylfurfural (HMF) from carbohydrates using metal chloride catalysts. A 33.2 % yield of HMF was obtained from raw Dioscorea composita biomass with high starch by using a catalyst system composed of CrCl3·6H2O and LaCl3·6H2O at 120 °C for 4 h in N,N-dimethylacetamide containing lithium chloride. The catalyst system is also cost-effective for the conversion of soluble starch into HMF. In addition, levulinic acid was not formed in the reactions.

De novo transcriptome assembly and the putative biosynthetic pathway of steroidal sapogenins of Dioscorea composita.

The plant Dioscorea composita has important applications in the medical and energy industries, and can be used for the extraction of steroidal sapogenins (important raw materials for the synthesis of steroidal drugs) and bioethanol production. However, little is known at the genetic level about how sapogenins are biosynthesized in this plant. Using Illumina deep sequencing, 62,341 unigenes were obtained by assembling its transcriptome, and 27,720 unigenes were annotated. Of these, 8,022 unigenes were mapped to 243 specific pathways, and 531 unigenes were identified to be involved in 24 secondary metabolic pathways. 35 enzymes, which were encoded by 79 unigenes, were related to the biosynthesis of steroidal sapogenins in this transcriptome database, covering almost all the nodes in the steroidal pathway. The results of real-time PCR experiments on ten related transcripts (HMGR, MK, SQLE, FPPS, DXS, CAS, HMED, CYP51, DHCR7, and DHCR24) indicated that sapogenins were mainly biosynthesized by the mevalonate pathway. The expression of these ten transcripts in the tuber and leaves was found to be much higher than in the stem. Also, expression in the shoots was low. The nucleotide and protein sequences and conserved domains of four related genes (HMGR, CAS, SQS, and SMT1) were highly conserved between D. composita and D. zingiberensis; but expression of these four genes is greater in D. composita. However, there is no expression of these key enzymes in potato and no steroidal sapogenins are synthesized.

A New Source of Elemol Rich Essential Oil and Existence of Multicellular Oil Glands in Leaves of the Dioscorea Species

Dioscorea species is a very important food and drug plant. The tubers of the plant are extensively used in food and drug purposes owing to the presence of steroidal constituent's diosgenin in the tubers. In the present study, we report for the first time that the leaves of Dioscorea composita and Dioscorea floribunda grown under the field conditions exhibited the presence of multicellular oil glands on the epidermal layers of the plants using stereomicroscopy (SM) and scanning electron microscopy (SEM). Essential oil was also isolated from the otherwise not useful herbage of the plant, and gas chromatographic-mass spectroscopy analysis revealed confirmation of the essential oil constituents. Out of the 76 compounds detected in D. floribunda and 37 from D. composita essential oil, major terpenoids which are detected and reported for Dioscorea leaf essential oil are α-terpinene, nerolidol, citronellyl acetate, farnesol, elemol, α-farnesene, valerenyl acetate, and so forth. Elemol was detected as the major constituent of both the Dioscorea species occupying 41% and 22% of D. Floribunda and D. composita essential oils, respectively. In this paper, we report for the first time Dioscorea as a possible novel bioresource for the essential oil besides its well-known importance for yielding diosgenin.

Biotransformation of n‐hexadecane by cell suspension cultures of Cinchona robusta and Dioscorea composita

This manuscript evaluates the phytotoxicity and biotransformation of n-hexadecane as well as peroxidase activity and cytochrome P450 concentration in microsomes for cell suspension cultures of Cinchona robusta and Dioscorea composita. Phytotoxicity was evaluated based on viability and growth. Cell cultures were exposed to a 2 and 4% (v/v) dose of n-hexadecane. The biotransformation of n-hexadecane was determined based on labeled recovery in polar, nonpolar, and cell residue fractions after cell culture extraction during exponential cell growth phase and stationary phase. Differences were observed in accumulation of label during cell growth phase and stationary phase for the cells of the two plants. Differences also were observed between phases for label in polar and nonpolar fractions. Thin-layer chromatography determined labeled intermediates and some were identified. The activity of peroxidase and concentration of cytochrome P450 was lower in C. robusta than in controls and greater in D. composita than in controls. In vitro biotransformation was not successful.

Comparative uptake and metabolism of 2-[14C]-2,4-dichlorophenoxyacetic acid in callus cultures of monocot (Dioscorea spp.) and dicot (Nicotiana tabacum L.) plants

(Comparative uptake and metabolism of 2-[14C]-2,4-dichlorophenoxyacetic acid in callus cultures of monocot (Dioscorea spp.) and dicot (Nicotiana tabacum L.) plants). The uptake and metabolism of 2-[14C]-2,4-dichlorophenoxyacetic acid (2,4-D) were investigated in leaf calluses of Nicotiana tabacum, tuber calluses of Dioscorea opposita and calluses derived from zygotic embryos, leaves and petioles of Dioscorea composita. Striking similarities were evident in the patterns of 2,4-D metabolites and their chemical characteristics in the three callus types of D. composita compared, but significant differences were detected among the patterns of rnetabolites in the three species studied. Preliminary investigations on the stability of various metabolites (separated using TLC) by hydrolysis showed that sugar esters appeared to be the major metabolites in tobacco whilst in yams (D. opposita) glycosides were shown to be the main ones, which indicated a similarity between plants of Gramineae and Dioscoreaceae in terms of 2,4-D metabolism. Release of 2,4-D from tobacco callus cells upon their transfer to 2,4-D-free medium was detected and the implications of this are discussed in relation to the cultural conditions necessary to induce morphogenesis in vitro.

In vitro shoot culture and microtuber induction in the steroid yam Dioscorea composita Hemsl

The individual effects of sucrose, plant growth regulators and basal salt media formulations were investigated on microtuber induction and development in shoot cultures of the steroid yam Dioscorea composita. Sucrose at 8% (w/v) was the single most significant medium constituent for microtuber induction. Of the four cytokinins tested, 6-benzyladenine at 1.25 and 2.5 μM showed strong inhibitory effects on microtuber induction. By contrast, the auxins α-naphthaleneacetic acid and indole-3-butyric acid at 5.0 μM showed striking promotive effects on microtuber induction and growth. In the presence of either one of these auxins at 5.0 μM shoot cultures produced microtubers weighing 300–400 mg fresh weight whilst kinetin, 6-(γ,γ-dimethylallylamino)-purine, 6-benzyladenine and abscisic acid failed to promote microtuber growth (microtubers weighed generally <200 mg). Media formulations Lloyd and MacCown and White supported the lowest frequencies of microtuber induction when kinetin was present at 2.5 μM. Anderson Rhododendron was as effective as Murashige and Skoog overall in promoting both microtuber induction and growth. When removed from cultures and planted in sterilized moist sand, microtubers sprouted readily (60–87% within 2 weeks) and produced vigorous shoot growth and after 5–7 months minitubers of sizes (30–80 g) suitable for direct field planting.

ISOLAMENTO E DETERMINAÇÃO DE ALGUMAS CARACTERÍSTICAS FÍSICAS, QUÍMICAS E FÍSICO-QUÍMICAS DO AMIDO DE BARBASCO (Dioscorea composita)

Objetiva isolar e determinar algumas propriedades do amido de barbasco (Dioscorea canposita), a fim de definir suas aplicações tecnológicas. Os parâmetros investigados foram, composição centesimal (umidade, proteína, gordura, fibra, cinza e carboidratos), capacidade de ligação com água (WBC), viscosidade intrínseca, propriedades viscoamilográficas , número de grupos de glicose por segmento de amilose e de amilopectina, efeito da alfa-amilase, microscopia do grânulo, estimação do conteúdo de amilose e amilopectina e densidade absoluta do amido. Procurou-se ainda, observar a possibilidade do seu emprego industrial , levando-se em consideração suas características físicas , químicas e físico-químicas. Os resultados de extração de duas variedades indicaram que o barbasco contém 31,0% e 28,0% de amido e que seus grânulos são arredondados com tamanhos variando entre 7,5 e 8,0 mícrons respectivamente e que os teôres de amiloses foram de 26,0 e 26,30 respectivamente. Suas propriedades físico químicas demonstraram que os amidos possuem rápida gelatinização, provavelmente em razão de baixa e homogênea associação intra-estrutural, o que implica em pequeno tempo de cocção.

Some Biological Effects of Dioscorea composita and Dioscorea mexicana Glycosidic Fractions

AbstractBiological activity of the glycosidic fractions from Dioscorea composita and D. mexicana was tested against two insect species and a weed; findings include delay of molting of Tenebrio molitor larvae, high toxicity to Anastrepha ludens adults, and inhibition of growth of Cassia jalapensis, mainly due to D. mexicana glycosides, whose composition differs from that of D. composita particularly in the presence of furostanic (semi-open chained) compounds, and whose structural similarity with ecdysones could explain delay of metamorphosis.

Callus induction and plant regeneration from excised zygotic embryos of the seed-propagated yams Dioscorea composita Hemsl. and D. cayenensis Lam.

A tissue culture method for regeneration of plantlets from calluses of Dioscorea composita Hemsl. and Dioscorea cayenensis L. is described. Zygotic embryos were used as initial explants. Calluses were obtained on Murashige & Skoog basal medium supplemented with 18 μM 2,4-D and plantlets were regenerated on media containing 0.1 μM zeatin and 3.3 mM glutamine according to previously described protocols [3]. Inclusion of 0.3% (w/v) activated charcoal in media did not increase callusing. Regeneration of plantlets from D. cayenensis calluses occurred only at low levels of 2,4-D (2.25 μM) contained in the media tested. The results indicated that there were genotype-dependent differences between the yam species in their ability to regenerate plantlets in vitro.