Methyl jasmonate inducible UGT79A18 is a novel glycosyltransferase involved in the bacoside biosynthetic pathway in Bacopa monnieri.

Bacosides are dammarane-type triterpenoidal saponins in Bacopa monnieri and have various pharmacological applications. All the bacosides are diversified from two isomers, i.e., jujubogenin and pseudojujubogenin. The biosynthetic pathway of bacoside is not well elucidated. In the present study, we characterized a UDP-glycosyltransferase, UGT79A18, involved in the glycosylation of pseudojujubogenin. UGT79A18 shows higher expression in response to 5 h of wounding, and 3 h of MeJA treatment. The recombinant UGT79A18 shows in vitro activity against a wide range of flavonoids and triterpenes and has a substrate preference for protopanaxadiol, a dammarane-type triterpene. Secondary metabolite analysis of overexpression and knockdown lines of UGT79A18 in B. monnieri identify bacopasaponin D, bacopaside II, bacopaside N2 and pseudojujubogenin glucosyl rhamnoside as the major bacosides that were differentially accumulated. In the overexpression lines of UGT79A18, we found 1.7-fold enhanced bacopaside II, 8-fold enhanced bacopasaponin D, 3-fold enhanced pseudojujubogenin glucosyl rhamnoside, and 1.6-fold enhanced bacopaside N2 content in comparison with vector control plant, whereas in the knockdown lines of UGT79A18, we found 1.4-fold reduction in bacopaside II content, 3-fold reduction in the bacopasaponin D content, 2-fold reduction in the pseudojujubogenin glucosyl rhamnoside content, and 1.5-fold reduction in bacopaside N2 content in comparison with vector control. These results suggest that UGT79A18 is a significant UDP glycosyltransferase involved in glycosylating pseudojujubogenin and enhancing the pseudojujubogenin-derived bacosides.

Transcriptome analysis of waterlogging-induced adventitious root and control taproot of Mentha arvensis.

KEY MESSAGE: The present study reports differentially expressed transcripts in the waterlogging-induced adventitious root (AR) of Mentha arvensis; the identified transcripts will help to understand AR development and improve waterlogging stress response. Waterlogging notably hampers plant growth in areas facing waterlogged soil conditions. In our previous findings, Mentha arvensis was shown to adapt better in waterlogging conditions by initiating the early onset of adventitious root development. In the present study, we compared the transcriptome analysis of adventitious root induced after the waterlogging treatment with the control taproot. The biochemical parameters of total carbohydrate, total protein content, nitric oxide (NO) scavenging activity and antioxidant enzymes, such as catalase activity (CAT) and superoxide dismutase (SOD) activity, were enhanced in the adventitious root compared with control taproot. Analysis of differentially expressed genes (DEGs) in adventitious root compared with the control taproot were grouped into four functional categories, i.e., carbohydrate metabolism, antioxidant activity, hormonal regulation, and transcription factors that could be majorly involved in the development of adventitious roots. Differential expression of the upregulated and uniquely expressing thirty-five transcripts in adventitious roots was validated using qRT-PCR. This study has generated the resource of differentially and uniquely expressing transcripts in the waterlogging-induced adventitious roots. Further functional characterization of these transcripts will be helpful to understand the development of adventitious roots, leading to the resistance towards waterlogging stress in Mentha arvensis.

Ocimum sanctum, OscWRKY1, regulates phenylpropanoid pathway genes and promotes resistance to pathogen infection in Arabidopsis.

KEY MESSAGE: OscWRKY1 from Ocimum sanctum positively regulates phenylpropanoid pathway genes and rosmarinic acid content. OscWRKY1 overexpression promotes resistance against bacterial pathogen in Arabidopsis. WRKY transcription factor (TF) family regulates various developmental and physiological functions in plants. PAL genes encode enzymes which are involved in plant defense responses, but the direct regulation of PAL genes and phenylpropanoid pathway through WRKY TF's is not well characterized. In the present study, we have characterized an OscWRKY1 gene from Ocimum sanctum which shows induced expression by methyl jasmonate (MeJA), salicylic acid (SA), and wounding. The recombinant OscWRKY1 protein binds to the DIG-labeled (Digoxigenin) W-box cis-element TTGAC[C/T] and activates the LacZ reporter gene in yeast. Overexpression of OscWRKY1 enhances Arabidopsis resistance towards Pseudomonas syringae pv. tomato Pst DC3000. Upstream activator sequences of PAL and C4H have been identified to contain the conserved W-box cis-element (TTGACC) in both O. sanctum and Arabidopsis. OscWRKY1 was found to interact with W-box cis-element present in the PAL and C4H promoters. Silencing of OscWRKY1 using VIGS resulted in reduced expression of PAL, C4H, COMT, F5H and 4CL transcripts. OscWRKY1 silenced plants exhibit reduced PAL activity, whereas, the overexpression lines of OscWRKY1 in Arabidopsis exhibit increased PAL activity. Furthermore, the metabolite analysis of OscWRKY1 silenced plants showed reduced rosmarinic acid content. These results revealed that OscWRKY1 positively regulates the phenylpropanoid pathway genes leading to the alteration of rosmarinic acid content and enhances the resistance against bacterial pathogen in Arabidopsis.

Determination of the Physicochemical Quality of Groundwater and its Potential Health Risk for Drinking in Oromia, Ethiopia.

This study aimed to determine the physicochemical quality of groundwater and its potential health risk for drinking in Oromia, Ethiopia. The groundwater samples were collected from 17 sampling stations in the dry and wet season in the Sebeta zone, Oromia, from March to August 2020. Metals and physicochemical parameters, and selected heavy metals, such as iron (Fe), copper (Cu), manganese (Mn), chromium (Cr), zinc (Zn), and lead (Pb) were monitored. The data were analyzed using multivariate statistical methods (Pearson's Correlation and T-test). The means seasonal variations were higher in the dry season than in the wet season except for pH and Turbidity. The variation was significant for most parameters except Pb, Zn, chlorine, Total Alkaline, Magnesium Hardness, Calcium Hardness ), and Turbidity. There was a strong and positive correlation between Total dissolved solids (TDS) and Conductivity), (pH and Cr), (T.H. and Magnesium (Mg)), (bicarbonate and Calcium (Ca), (Zn and Turbidity) in the dry season; and (T.H. with Potassium (K), (Pb and Fe); (bicarbonate and T.H.); (Ca and Mg); (Na and T.A.,) in the wet season. The hazard index (H.I.) values in the dry season (HI = 1.331) were higher than in the wet season (HIadults = 0.075). Likewise, the H.I. (dry season) was higher (HIchildren = 1.861) than in the wet season (HIchildren = 0.105). Chronic groundwater exposure at drinking sources in the dry season is a potential health risk to humans in general and is relatively high for children. Urgent management and close monitoring are required for drinking groundwater sources and other nearby residents' safety areas.

An insight into microRNA biogenesis and its regulatory role in plant secondary metabolism.

KEY MESSAGE: The present review highlights the regulatory roles of microRNAs in plant secondary metabolism and focuses on different bioengineering strategies to modulate secondary metabolite content in plants. MicroRNAs (miRNAs) are the class of small endogenous, essential, non-coding RNAs that riboregulate the gene expression involved in various biological processes in most eukaryotes. MiRNAs has emerged as important regulators in plants that function by silencing target genes through cleavage or translational inhibition. These miRNAs plays an important role in a wide range of plant biological and metabolic processes, including plant development and various environmental response controls. Several important plant secondary metabolites like alkaloids, terpenoids, and phenolics are well studied for their function in plant defense against different types of pests and herbivores. Due to the presence of a wide range of biological and pharmaceutical properties of plant secondary metabolites, it is important to study the regulation of their biosynthetic pathways. The contribution of miRNAs in regulating plant secondary metabolism is not well explored. Recent advancements in molecular techniques have improved our knowledge in understanding the molecular function of genes, proteins, enzymes, and small RNAs involved in different steps of secondary metabolic pathways. In the present review, we have discussed the recent progress made on miRNA biogenesis, its regulation, and highlighted the current research developed in the field of identification, analysis, and characterizations of various miRNAs that regulate plant secondary metabolism. We have also discussed how different bioengineering strategies such as artificial miRNA (amiRNA), endogenous target mimicry, and CRISPR/Cas9 could be utilized to enhance the secondary metabolite production in plants.

Bm-miR172c-5p Regulates Lignin Biosynthesis and Secondary Xylem Thickness by Altering the Ferulate 5 Hydroxylase Gene in Bacopa monnieri.

MicroRNAs (miRNAs) are small non-coding, endogenous RNAs containing 20-24 nucleotides that regulate the expression of target genes involved in various plant processes. A total of 1,429 conserved miRNAs belonging to 95 conserved miRNA families and 12 novel miRNAs were identified from Bacopa monnieri using small RNA sequencing. The Bm-miRNA target transcripts related to the secondary metabolism were further selected for validation. The Bm-miRNA expression in shoot and root tissues was negatively correlated with their target transcripts. The Bm-miRNA cleavage sites were mapped within the coding or untranslated region as depicted by the modified RLM-RACE. In the present study, we validate three miRNA targets, including asparagine synthetase, cycloartenol synthase and ferulate 5 hydroxylase (F5H) and elucidate the regulatory role of Bm-miR172c-5p, which cleaves the F5H gene involved in the lignin biosynthesis. Overexpression (OE) of Bm-miR172c-5p precursor in B. monnieri suppresses F5H gene, leading to reduced lignification and secondary xylem thickness under control and drought stress. By contrast, OE of endogenous target mimics (eTMs) showed enhanced lignification and secondary xylem thickness leading to better physiological response under drought stress. Taken together, we suggest that Bm-miRNA172c-5p might be a key player in maintaining the native phenotype of B. monnieri under control and different environmental conditions.

Characterization of MYB35 regulated methyl jasmonate and wound responsive Geraniol 10-hydroxylase-1 gene from Bacopa monnieri.

MAIN CONCLUSION: BmG10H-1 transcript from B. monnieri was functionally active. BmG10H-1 promoter drives GUS activity in response to MeJA and wounding. BmMYB35 regulates BmG10H-1 transcript by binding to its promoter. Geraniol 10-hydroxylase (G10H) is one of the important regulatory cytochrome P450 monooxygenase, which is involved in the biosynthesis of monoterpene alkaloids. However, G10H is not characterized at the enzymatic or at the regulatory aspect in B. monnieri. In the present study, we have identified two transcripts of BmG10H (BmG10H-1and BmG10H-2) and characterized the methyl jasmonate (MeJA) and wound responsive BmG10H-1 transcript from B. monnieri. BmG10H-1 showed induced expression after 3 h of MeJA and wounding treatment in the shoot. Yeast purified recombinant BmG10H-1 protein is enzymatically active, having Vmax of 0.16 µMsec-1 µg-1 protein and catalyzes the hydroxylation of geraniol to 10-hydroxy geraniol. The BmG10H-1 promoter was isolated by using the genome walking method. BmG10H-1 promoter can drive GUS expression in transgenic Arabidopsis thaliana. GUS activity of MeJA and wound-treated Arabidopsis seedlings were found to be increased as compared to the control untreated seedlings, whereas no GUS activity was found in deleted MeJA responsive and W-box cis-elements. This shows that the BmG10H-1 promoter contains functional MeJA (TGACG) and wound responsive (TGACCT) cis-elements. Further, shoot specific and MeJA responsive recombinant BmMYB35 protein was purified, which binds with the MYB recognition cis-element (TGGTTA) present in the BmG10H-1 promoter and transcriptionally activates the reporter gene in yeast. In conclusion, the characterization of MeJA and wound responsive BmG10H-1 provides novel information about its transcriptional regulation by binding with MYB transcription factor in B. monnieri.

Asparagus racemosus bZIP transcription factor-regulated squalene epoxidase (ArSQE) promotes germination and abiotic stress tolerance in transgenic tobacco.

A. racemosus is a rich source of pharmacologically active steroidal saponins. Most of the studies are related to its chemistry and pharmacology, but the pathway involved in the biosynthesis of steroidal saponin is not much emphasized. Squalene epoxidase acts as a rate-limiting enzyme in this biosynthesis. In this study, we have selected root specific squalene epoxidase ArSQE from A. racemosus for its characterization. ArSQE was able to complement ergosterol auxotrophy in erg1 yeast mutants. Mutants were sensitive to the antifungal drug terbinafine, whereas ArSQE complementation made them tolerant to the same drug. ArSQE plays a significant role in early germination in transgenic tobacco. The transgenic tobacco seedlings overexpressing ArSQE were tolerant to terbinafine and abiotic stress. Expression analysis of transcripts in ArSQE transgenic lines suggests that it mostly affects ABA, GA, stress, and sterol related functions in transgenic tobacco. Further, root specific MeJA responsive A. racemosus bZIP transcription factors (TFs), ArTGA1 and ArTGA2, were identified that bind to MeJA responsive cis-element present in the promoter region of ArSQE. Characterization of ArSQE of A. racemosus provides new information about its regulation through MeJA responsive bZIP TF along with its role in the development and abiotic stress response in transgenic tobacco.

Structure, evolution and diverse physiological roles of SWEET sugar transporters in plants.

KEY MESSAGE: Present review describes the structure, evolution, transport mechanism and physiological functions of SWEETs. Their application using TALENs and CRISPR/CAS9 based genomic editing approach is discussed. Sugars Will Eventually be Exported Transporters (SWEET) proteins were first identified in plants as the novel family of sugar transporters which mediates the translocation of sugars across cell membranes. The SWEET family of sugar transporters is unique in terms of their structure which contains seven predicted transmembrane domains with two internal triple-helix bundles which possibly originate due to prokaryotic gene duplication. SWEETs perform diverse physiological functions such as pollen nutrition, nectar secretion, seed filling, phloem loading, and pathogen nutrition which we have discussed in the present review. We also discuss how transcriptional activator-like effector nucleases (TALENs) and CRISPR/CAS9 genome editing tools are used to engineer SWEET mutants which modulate pathogen resistance in plants and its applications in the field of agriculture. The expression of SWEETs promises to implement insights into many other cellular transport mechanisms. To conclude, the present review highlights the recent aspects which will further develop better understanding of molecular evolution, structure, and function of SWEET transporters in plants.

Recent advances in steroidal saponins biosynthesis and in vitro production.

MAIN CONCLUSION: Steroidal saponins exhibited numerous pharmacological activities due to the modification of their backbone by different cytochrome P450s (P450) and UDP glycosyltransferases (UGTs). Plant-derived steroidal saponins are not sufficient for utilizing them for commercial purpose so in vitro production of saponin by tissue culture, root culture, embryo culture, etc, is necessary for its large-scale production. Saponin glycosides are the important class of plant secondary metabolites, which consists of either steroidal or terpenoidal backbone. Due to the existence of a wide range of medicinal properties, saponin glycosides are pharmacologically very important. This review is focused on important medicinal properties of steroidal saponin, its occurrence, and biosynthesis. In addition to this, some recently identified plants containing steroidal saponins in different parts were summarized. The high throughput transcriptome sequencing approach elaborates our understanding related to the secondary metabolic pathway and its regulation even in the absence of adequate genomic information of non-model plants. The aim of this review is to encapsulate the information related to applications of steroidal saponin and its biosynthetic enzymes specially P450s and UGTs that are involved at later stage modifications of saponin backbone. Lastly, we discussed the in vitro production of steroidal saponin as the plant-based production of saponin is time-consuming and yield a limited amount of saponins. A large amount of plant material has been used to increase the production of steroidal saponin by employing in vitro culture technique, which has received a lot of attention in past two decades and provides a way to conserve medicinal plants as well as to escape them for being endangered.

MaRAP2-4, a waterlogging-responsive ERF from Mentha, regulates bidirectional sugar transporter AtSWEET10 to modulate stress response in Arabidopsis.

As waterlogging and successive events severely influence growth and development of economically important plants, we attempted to characterize the role of a waterlogging-responsive group I (A-6) ethylene response factor (MaRAP2-4) from Mentha arvensis. Waterlogging, ethylene and methyl jasmonate rapidly induced the expression of MaRAP2-4. MaRAP2-4 interacted with multiple cis-elements like dehydration response elements (DRE1/2), anoxia/jasmonic acid response element (JARE) and GCC box showing its involvement in multiple responses. MaRAP2-4 localizes in the nucleus and acts as a transcriptional activator. Truncation and internal deletion identified a 20 amino acids potential transactivation domain (PLPSSVDAKLEAICQSLAIN) in MaRAP2-4. MaRAP2-4 transgenic Arabidopsis showed enhanced waterlogging and subsequent oxidative stress tolerance. Microarray analysis revealed that within up-regulated genes 483, 212 and 132 promoters carry either single or multiple copies of DRE, JARE and GCC cis-element/s, respectively. Within these promoters, a large section belongs to carbohydrate metabolism/transport, including many SWEET transporters. Further analysis showed MaRAP2-4 specifically targets two positions in AtSWEEET10 promoter carrying DRE and/or GCC box that might regulate carbohydrate availability and waterlogging tolerance. These results demonstrate that MaRAP2-4 is a positive regulator of waterlogging tolerance, and as energy-consuming processes such as carbohydrate biosynthesis are reduced under waterlogging-induced hypoxia, sugar transport through SWEETs may be the primary option to make sugar available to the required tissue.

Comparative transcriptome analysis of shoot and root tissue of Bacopa monnieri identifies potential genes related to triterpenoid saponin biosynthesis.

BACKGROUND: Bacopa monnieri commonly known as Brahmi is utilized in Ayurveda to improve memory and many other human health benefits. Bacosides enriched standardized extract of Bacopa monnieri is being marketed as a memory enhancing agent. In spite of its well known pharmacological properties it is not much studied in terms of transcripts involved in biosynthetic pathway and its regulation that controls the secondary metabolic pathway in this plant. The aim of this study was to identify the potential transcripts and provide a framework of identified transcripts involved in bacosides production through transcriptome assembly. RESULTS: We performed comparative transcriptome analysis of shoot and root tissue of Bacopa monnieri in two independent biological replicate and obtained 22.48 million and 22.0 million high quality processed reads in shoot and root respectively. After de novo assembly and quantitative assessment total 26,412 genes got annotated in root and 18,500 genes annotated in shoot sample. Quality of raw reads was determined by using SeqQC-V2.2. Assembled sequences were annotated using BLASTX against public database such as NR or UniProt. Searching against the KEGG pathway database indicated that 37,918 unigenes from root and 35,130 unigenes from shoot were mapped to 133 KEGG pathways. Based on the DGE data we found that most of the transcript related to CYP450s and UDP-glucosyltransferases were specifically upregulated in shoot tissue as compared to root tissue. Finally, we have selected 43 transcripts related to secondary metabolism including transcription factor families which are differentially expressed in shoot and root tissues were validated by qRT-PCR and their expression level were monitored after MeJA treatment and wounding for 1, 3 and 5 h. CONCLUSIONS: This study not only represents the first de novo transcriptome analysis of Bacopa monnieri but also provides information about the identification, expression and differential tissues specific distribution of transcripts related to triterpenoid sapogenin which is one of the most important pharmacologically active secondary metabolite present in Bacopa monnieri. The identified transcripts in this study will establish a foundation for future studies related to carrying out the metabolic engineering for increasing the bacosides biosynthesis and its regulation for human health benefits.

Comparative transcriptome analysis reveals candidate genes for the biosynthesis of natural insecticide in Tanacetum cinerariifolium.

BACKGROUND: Pyrethrins are monoterpenoids and consist of either a chrysanthemic acid or pyrethric acid with a rethrolone moiety. Natural pyrethrins are safe and eco-friendly while possessing strong insecticidal properties. Despite such advantages of commercial value coming with the eco-friendly tag, most enzymes/genes involved in the pyrethrin biosynthesis pathway remain unidentified and uncharacterized. Since the flowers of Tanacetum cinerariifolium are rich in major pyrethrins, next generation transcriptome sequencing was undertaken to compare the flowers and the leaves of the plant de novo to identify differentially expressed transcripts and ascertain which among them might be involved in and responsible for the differential accumulation of pyrethrins in T. cinerariifolium flowers. RESULTS: In this first tissue specific transcriptome analysis of the non-model plant T. cinerariifolium, a total of 23,200,000 and 28,500,110 high quality Illumina next generation sequence reads, with a length of 101 bp, were generated for the flower and leaf tissue respectively. After functional enrichment analysis and GO based annotation using public protein databases such as UniRef, PFAM, SMART, KEGG and NR, 4443 and 8901 unigenes were identified in the flower and leaf tissue respectively. These could be assigned to 13344 KEGG pathways and the pyrethrin biosynthesis contextualized. The 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway was involved in the biosynthesis of acid moiety of pyrethrin and this pathway predominated in the flowers as compared to the leaves. However, enzymes related to oxylipin biosynthesis were found predominantly in the leaf tissue, which suggested that major steps of pyrethrin biosynthesis occurred in the flowers. CONCLUSIONS: Transcriptome comparison between the flower and leaf tissue of T. cinerariifolium provided an elaborate list of tissue specific transcripts that was useful in elucidating the differences in the expression of the biosynthetic pathways leading to differential presence of pyrethrin in the flowers. The information generated on genes, pathways and markers related to pyrethrin biosynthesis in this study will be helpful in enhancing the production of these useful compounds for value added breeding programs. Related proteome comparison to overlay our transcriptome comparison can generate more relevant information to better understand flower specific accumulation of secondary metabolites in general and pyrethrin accumulation in particular.

Waterlogging and submergence stress: affects and acclimation.

Submergence, whether partial or complete, imparts some serious consequences on plants grown in flood prone ecosystems. Some plants can endure these conditions by embracing various survival strategies, including morphological adaptations and physiological adjustments. This review summarizes recent progress made in understanding of the stress and the acclimation responses of plants under waterlogged or submerged conditions. Waterlogging and submergence are often associated with hypoxia development, which may trigger various morphological traits and cellular acclimation responses. Ethylene, abscisic acid, gibberellic acid and other hormones play a crucial role in the survival process which is controlled genetically. Effects at the cellular level, including ATP management, starch metabolism, elemental toxicity, role of transporters and redox status have been explained. Transcriptional and hormonal interplay during this stress may provide some key aspects in understanding waterlogging and submergence tolerance. The level and degree of tolerance may vary depending on species or climatic variations which need to be studied for a proper understanding of waterlogging stress at the global level. The exploration of regulatory pathways and interplay in model organisms such as Arabidopsis and rice would provide valuable resources for improvement of economically and agriculturally important plants in waterlogging affected areas.

PsAP2 an AP2/ERF family transcription factor from Papaver somniferum enhances abiotic and biotic stress tolerance in transgenic tobacco.

The AP2/ERFs are one of the most important family of transcription factors which regulate multiple responses like stress, metabolism and development in plants. We isolated PsAP2 a novel AP2/ERF from Papaver somniferum which was highly upregulated in response to wounding followed by ethylene, methyl jasmonate and ABA treatment. PsAP2 showed specific binding with both DRE and GCC box elements and it was able to transactivate the reporter genes in yeast. PsAP2 overexpressing transgenic tobacco plants exhibited enhanced tolerance towards both abiotic and biotic stresses . Real time transcript expression analysis showed constitutive upregulation of tobacco Alternative oxidase1a and Myo-inositol-1-phosphate synthase in PsAP2 overexpressing tobacco plants. Further, PsAP2 showed interaction with NtAOX1a promoter in vitro, it also specifically activated the NtAOX1a promoter in yeast and tobacco BY2 cells. The silencing of PsAP2 using VIGS lead to significant reduction in the AOX1 level in P. somniferum. Taken together PsAP2 can directly bind and transcriptionally activate NtAOX1a and its overexpression in tobacco imparted increased tolerance towards both abiotic and biotic stress.

De novo leaf and root transcriptome analysis identified novel genes involved in steroidal sapogenin biosynthesis in Asparagus racemosus.

BACKGROUND: Saponins are mainly amphipathic glycosides that posses many biological activities and confer potential health benefits to humans. Inspite of its medicinal attributes most of the triterpenes and enzymes involved in the saponin biosynthesis remains uncharacterized at the molecular level. Since the major steroidal components are present in the roots of A. racemosus our study is focussed on the comparative denovo transcriptome analysis of root versus leaf tissue and identifying some root specific transcripts involved in saponin biosynthesis using high-throughput next generation transcriptome sequencing. RESULTS: After sequencing, de novo assembly and quantitative assessment, 126861 unigenes were finally generated with an average length of 1200 bp. Then functional annotation and GO enrichment analysis was performed by aligning all-unigenes with public protein databases including NR, SwissProt, and KEGG. Differentially expressed genes in root were initially identified using the RPKM method using digital subtraction between root and leaf. Twenty seven putative secondary metabolite related transcripts were experimentally validated for their expression in root or leaf tissue using q-RT PCR analysis. Most of the above selected transcripts showed preferential expression in root as compared to leaf supporting the digitally subtracted result obtained. The methyl jasmonate application induces the secondary metabolite related gene transcripts leading to their increased accumulation in plants. Therefore, the identified transcripts related to saponin biosynthesis were further analyzed for their induced expression after 3, 5 and 12 hours of exogenous application of Methyl Jasmonate in tissue specific manner. CONCLUSIONS: In this study, we have identified a large set of cDNA unigenes from A. racemosus leaf and root tissue. This is the first transcriptome sequencing of this non-model species using Illumina, a next generation sequencing technology. The present study has also identified number of root specific transcripts showing homology with saponin biosynthetic pathway. An integrated pathway of identified saponin biosynthesis transcripts their tissue specific expression and induced accumulation after methyl jasmonate treatment was discussed.

De novo sequencing and comparative analysis of holy and sweet basil transcriptomes.

BACKGROUND: Ocimum L. of family Lamiaceae is a well known genus for its ethnobotanical, medicinal and aromatic properties, which are attributed to innumerable phenylpropanoid and terpenoid compounds produced by the plant. To enrich genomic resources for understanding various pathways, de novo transcriptome sequencing of two important species, O. sanctum and O. basilicum, was carried out by Illumina paired-end sequencing. RESULTS: The sequence assembly resulted in 69117 and 130043 transcripts with an average length of 1646 ± 1210.1 bp and 1363 ± 1139.3 bp for O. sanctum and O. basilicum, respectively. Out of the total transcripts, 59648 (86.30%) and 105470 (81.10%) from O. sanctum and O. basilicum, and respectively were annotated by uniprot blastx against Arabidopsis, rice and lamiaceae. KEGG analysis identified 501 and 952 transcripts from O. sanctum and O. basilicum, respectively, related to secondary metabolism with higher percentage of transcripts for biosynthesis of terpenoids in O. sanctum and phenylpropanoids in O. basilicum. Higher digital gene expression in O. basilicum was validated through qPCR and correlated to higher essential oil content and chromosome number (O. sanctum, 2n = 16; and O. basilicum, 2n = 48). Several CYP450 (26) and TF (40) families were identified having probable roles in primary and secondary metabolism. Also SSR and SNP markers were identified in the transcriptomes of both species with many SSRs linked to phenylpropanoid and terpenoid pathway genes. CONCLUSION: This is the first report of a comparative transcriptome analysis of Ocimum species and can be utilized to characterize genes related to secondary metabolism, their regulation, and breeding special chemotypes with unique essential oil composition in Ocimum.

Identification, occurrence, and validation of DRE and ABRE Cis-regulatory motifs in the promoter regions of genes of Arabidopsis thaliana.

Plants posses a complex co-regulatory network which helps them to elicit a response under diverse adverse conditions. We used an in silico approach to identify the genes with both DRE and ABRE motifs in their promoter regions in Arabidopsis thaliana. Our results showed that Arabidopsis contains a set of 2,052 genes with ABRE and DRE motifs in their promoter regions. Approximately 72% or more of the total predicted 2,052 genes had a gap distance of less than 400 bp between DRE and ABRE motifs. For positional orientation of the DRE and ABRE motifs, we found that the DR form (one in direct and the other one in reverse orientation) was more prevalent than other forms. These predicted 2,052 genes include 155 transcription factors. Using microarray data from The Arabidopsis Information Resource (TAIR) database, we present 44 transcription factors out of 155 which are upregulated by more than twofold in response to osmotic stress and ABA treatment. Fifty-one transcripts from the one predicted above were validated using semiquantitative expression analysis to support the microarray data in TAIR. Taken together, we report a set of genes containing both DRE and ABRE motifs in their promoter regions in A. thaliana, which can be useful to understand the role of ABA under osmotic stress condition.

Antimalarial drug targets and drugs targeting dolichol metabolic pathway of Plasmodium falciparum.

Because of mutation and natural selection, development of drug resistance to the existing antimalarial is the major problem in malaria treatment. This problem has created an urgent need of novel antimalarial drug targets as well as lead compounds. The important characteristic of malaria is that it shows the phenomenon of balanced polymorphisms. Several traits have been selected in response to disease pressure. Therefore such factors must be explored to understand the pathogenesis of malaria infection in human host. Apicoplast, hub of metabolism is present in Plasmodium falciparum (causative agent of falciparum malaria) having similarities with plant plastid. Among several pathways in apicoplast, Dolichol metabolic pathway is one of the most important pathway and has been known to play role in parasite survival in the human host. In P.falciparum, a phosphorylated derivative of Dolichol participates in biosynthesis of glycoproteins. Several proteins of this pathway play role in post translational modifications of proteins involved in the signal transduction pathways, regulation of DNA replication and cell cycle. This pathway can be used as antimalarial drug target. This report has explored progress towards the study of proteins and inhibitors of Dolichol metabolic pathway. For more comprehensive analysis, the host genetic factors and drug-protein interaction have been covered.

Mentha arvensis exhibit better adaptive characters in contrast to Mentha piperita when subjugated to sustained waterlogging stress.

Waterlogging is becoming a critical threat to plants growing in areas prone to flooding. Some plants adapt various morphological and biochemical alterations which are regulated transcriptionally to cope with the situation. A comparative study of waterlogging response in two different varieties of Mentha namely Mentha piperita and Mentha arvensis was performed. M. arvensis showed better response towards waterlogging in comparison to M. piperita. M. arvensis maintained a healthy posture by utilizing its carbohydrate content; also, it showed a flourished vegetative growth under waterlogged condition. Soluble protein, chlorophyll content, relative water content, and nitric oxide scavenging activity were comparatively more salient in M. arvensis during this hypoxia treatment. Lipid peroxidation was less in M. arvensis. M. arvensis also showed vigorous outgrowth of adventitious roots to assist waterlogging tolerance. To further investigate the possible gene transcripts involved in this response, we did cDNA subtraction of waterlogging treated M. piperita and M. arvensis seedlings. cDNA subtraction has identified thirty seven novel putative Expressed Sequence Tags which were further classified functionally. Functional classification revealed that maximum percentage of proteins belonged to hypothetical proteins followed by proteins involved in biosynthesis. Some of the identified ESTs were further quantified for their induced expression in M. arvensis in comparison to M. piperita through quantitative real-time PCR.