Browsing by Author "Sabitri Kumari"

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Functional identification of AaDREB-9 transcription factor in Artemisia annua L. and deciphering its role in secondary metabolism under PEG-induced osmotic stress
(Springer, 2025) Sabitri Kumari; Nidhi Rai; Sneha Singh; Pajeb Saha; Mansi Singh Bisen; S. P. Rai
This study investigates the impact of polyethylene glycol (PEG)-induced osmotic stress in Artemisia annua, focusing on morpho-physiological changes, secondary metabolite synthesis, and gene expression. The finding reveals mild osmotic stress positively influenced glandular trichome density, which is a storage site for bioactive metabolites. However, higher levels of osmotic stress led to a significant decrease in the density of these trichomes. Under 8% PEG exposure proline, sugar, and anthocyanin levels increased, whereas decrease in growth, relative water content, chlorophyll content, and photosynthetic efficiency (Fv/Fm) was observed. Gas chromatography analysis showed a 1.49-fold increase in total essential oil compounds compared to controls, identifying seven major compounds: 1,8-cineole, camphor, β-caryophyllene, β-farnesene, β-coapane, selina-4,11-diene, and aristolone. Biosynthetic genes (PAL, CHS, ADS, DBR2, and CYP71AV1) exhibited upregulation by 2, 4.7, 4.1, 1.2, and 1.5-fold, respectively, when subjected to 8% PEG-induced stress, thereby enhancing artemisinin and other secondary metabolite production. To explore the role of AaAP2/ERF transcription factors under osmotic stress, a comprehensive genome-wide analysis identified 111 members across the DREB, ERF, AP2, RAV, and Soloists subfamilies. Promoter analysis revealed five homologues, with AaDREB-09 showing the highest upregulation (2.8-fold) in shoot tissues under osmotic stress. Further protein docking analysis demonstrated that AaDREB-09 binds to the promoters of AaDBR2 and AaCYP71AV1, enhancing the biosynthesis of artemisinin and dihydroartemisinic acid, thereby improving stress tolerance. These findings depict AaDREB-09 as a promising target for genetic engineering to enhance secondary metabolite production and stress resilience in A. annua. © Indian Society for Plant Physiology 2025.
Genome-wide identification of bZIP transcription factor family in Artemisia annua, its transcriptional profiling and regulatory role in phenylpropanoid metabolism under different light conditions
(Springer, 2023) Nidhi Rai; Sabitri Kumari; Sneha Singh; Pajeb Saha; Shashi Pandey-Rai
The basic leucine zipper (bZIP) protein transcription factors are known to modulate development, plant growth, metabolic response, and resistance to several biotic and abiotic stressors and have been widely studied in the model plant Arabidopsis thaliana. However, no comprehensive information about the bZIP transcription factor family in Artemisia annua has been explored to date. In this genome-wide study, we identified 61 bZIP TFs after removing false positives and incomplete sequences from Artemisia annua. Seven highly expressed homolog AabZIP TF genes under UV-B and differential light conditions in different tissues were identified from the publicly available microarray dataset as having their cis-regulatory elements involved in, flavonoids biosynthesis, seed-specific gene regulation, stress responses, and metabolic regulation. In-silico analysis and electrophoretic mobility shift assay (EMSA) confirmed the interaction of AabZIP19 TF over the AaPAL1 promoter in order to regulate the phenolics and flavonoid biosynthesis via the phenylpropanoid pathway. Further, RT-PCR analysis has been carried out to validate the transcript levels of selected AabZIP genes under white light, red light, blue light (45 min), and UV-B exposure (12 and 24 h). These genes have their highest expression levels under UV-B and blue light exposure, in contrast with white light. Therefore, the detection of ROS through staining confirms the accumulation of superoxide radicals and H2O2, and in addition to reducing ROS accumulation under UV-B and blue light irradiation, total phenols and flavonoids are significantly enhanced. This study laid the groundwork for deciphering the possible role of AabZIP TFs under different light stress-responsive conditions and in the regulation of secondary metabolism. © 2023, Prof. H.S. Srivastava Foundation for Science and Society.
Heterologous expression of AaLac1 gene in hairy roots and its role in secondary metabolism under PEG-induced osmotic stress condition in Artemisia annua L.
(Springer, 2024) Sabitri Kumari; Nidhi Rai; Sneha Singh; Pajeb Saha; Mansi Singh Bisen; Shashi Pandey-Rai
This study explores the Laccase gene (AaLac) family along with AaLac1 expression in hairy roots of A. annua. 42 AaLacs were identified by detecting three conserved domains: Cu-oxidase, Cu oxidase-2, and Cu oxidase-3. The physicochemical properties show that AaLacs are proteins with 541–1075 amino acids. These proteins are stable, with an instability index less than 40. Phylogenetic and motif studies have shown structural variants in AaLacs, suggesting functional divergence. 22 AaLac cis-regulatory elements were selected for their roles in drought stress, metabolic modulations, defense, and stress responses. A comparison of AtLac and AaLac proteins showed that 11 AtLacs mitigates stress reactions. In silico expression, analysis of 11 AtLacs showed that AtLac84 may function under osmotic stress. Thus, the Homolog AaLac1 was selected by expression profiling. The real-time PCR results showed that AaLac1 enhances osmotic stress tolerance in shoot and root samples. It was also used to analyze AaLac1, ADS, and CYP71AV1 gene expression in hairy roots via induction. The transformed hairy roots exhibited a greater capacity for PEG-induced osmotic stress tolerance in contrast to the untransformed roots. The gene expression analysis also depicted a significant increment in expression of AaLac1, ADS, and CYP71AV1 genes to 3.8, 6.9, and 3.1 folds respectively. The transformed hairy roots exhibited a significant increase of 2.2 and 1.4 fold in flavonoid and phenolic content respectively. Also, lignin content and artemisinin content increased by 7.05 folds and 95.6% with respect to the control. Thus, transformed hairy roots of A. annua under PEG-induced osmotic stress demonstrate the involvement of the AaLac1 gene in stress responses, lignin biosynthesis, and secondary metabolism production. © Prof. H.S. Srivastava Foundation for Science and Society 2024.
Modulation of morpho-physiological attributes and in situ analysis of secondary metabolites using Raman spectroscopy in response to red and blue light exposure in Artemisia annua
(Elsevier B.V., 2024) Nidhi Rai; Sabitri Kumari; Sneha Singh; Pajeb Saha; Adarsh Kumar Pandey; Shashi Pandey-Rai
Differential light conditions, such as variations in photoperiod, light quality, and light intensity, play a crucial role as external factors that can influence plant morphogenesis and secondary metabolism. However, there is still a lack of understanding of how Artemisia annua responds to monochromatic and dichromatic light regimes in terms of the different physiological mechanisms that control plant growth and secondary metabolite production. Therefore, the primary aim of this study was to investigate and assess the various physiological parameters, biochemical analysis, and molecular aspects in detail. Therefore, the plantlets were exposed to LED lighting such as monochromatic red light (R), monochromatic blue light (B), white light (W), and a combination of red and blue light (RB, 1:1) at a PPFD (photosynthetic photon flux density) of 200 mol. m−2. s−1 for 10 days. Our results indicate that exposure to RB light resulted in an immense increase in ROS accumulation, flavonoids, lignin, and artemisinin by 4.7-fold, 44%, and 53.4%, respectively, in contrast to W light. Whereas blue light led to increments of 160.2% in phenolic and 107.9% in anthocyanin content. RB and B light also influence the parameters of chlorophyll fluorescence, as well as leaf area, stomatal density, trichome size, antioxidant enzyme activity, and the production of more secondary metabolites to combat oxidative stress. Real-time PCR analysis of biosynthetic pathway-associated genes HMGR, DXR, DXS, FPS, ADS, CYP71AVI, DBR2, ALDH1, and flavonoid key biosynthesis pathway genes PAL, C4H, 4CL, CHS, and F3′H showed the highest increment under RB, light followed by B and R light exposure. Further, RB LED light has significant potential for enhancing natural bio-active compounds as revealed by Raman spectroscopy, such as camphor, limonene, terpene-4-ol, α pinene, 1,8-cineole, β-caryophyllene, artemisinin, kaempferol, luteolin, rutin, and caffeic acid in A. annua. Taken together, red and blue LEDs can serve as significant elicitors for the production of commercially important metabolites. © 2023 Elsevier B.V.
Pharmacology of Natural and Synthetic Phytoprotectants: Application and Consequences in Cancer Therapies
(Springer Nature, 2023) Sneha Singh; Pajeb Saha; Nidhi Rai; Sabitri Kumari; Shashi Pandey-Rai
Cancer represents one of the most fatal health issues, claiming the lives of millions of people each year. Tumorous growths can develop in almost any portion of the body and migrate to different parts. There are numerous treatment approaches available for cancer such as radiation therapy, photodynamic therapy, and cancer vaccinations. However, in most cases, they have adverse side effects. Thus, anticancer medications with higher efficiency and fewer side effects are desperately needed. Plants are a prospective source of such compounds. Natural plant bioactive substances have been used in traditional medicine since the dawn of humanity. These metabolites have also been implicated in providing protection to plants under various environmental influences, such as the influence of UV-B. Plant-based natural secondary metabolites/phytochemicals and their derivatives have great potential in the suppression of cancer development and metastasis. These biologically active compounds can be isolated from various plant parts, such as leaves, stems, barks, flowers, rhizomes, roots, and seeds. The natural bioactive compounds produced by plants during secondary metabolism have great pharmacological importance, especially as anticancer agents. Therefore, this chapter is an attempt to summarize the importance of various plant-derived compounds and their mechanism of action, which can be used in cancer therapies as anticancer agents. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2023.
PLANT CIRCADIAN RHYTHM: A BIOLOGICAL CLOCK AS DEVELOPMENTAL AND METABOLIC REGULATOR
(Nova Science Publishers, Inc., 2022) Nidhi Rai; Sabitri Kumari; Pajeb Saha; Apoorva; Sanjay Kumar Rai; Ram Prasad Meena; Shashi Pandey-Rai
Plants have an internal biological system that receives differential environmental fluctuations/stimuli such as temperature and light controlling circadian rhythm for maintenance of growth and developmental processes. These biological rhythms are regulated by the interaction of certain external signals and internal receptors. In plants, it is complex networking within transcription factors that functions in feedback loops. These light-induced phototropic controls are mediated by photoreceptors like phytochromes, cryptochrome, phototropin and master genes/regulators for floral development. These responses are genetic in nature and have master clock genes which further regulates many copies of the master transcription factor that are responsible for regulating/switch-on many important genes of metabolism by binding with the promoter region of target genes. The diurnal behavior in plants has been observed because of the existence of a feedback loop and a phosphorylation-dephosphorylation cycle. The light and temperatures positively regulate the induction of various genes along with a set of polycomb gene. Many long non-coding RNAs, micro-RNA and RNAdependent polymerases are indispensable parts of the diurnal cycle in plants. Environmental signals are involved in activating clock genes, and clock repressor circuits work to alienate and degrade these extrinsic gene activation pathways. Most transcription factors are cyclic and these subclasses can regulate clock parameters. Transcriptional regulators and associated chromatids that control transcriptional regulation are only one step in a multistep regulatory network. Post-translational relaxation, nuclear-cytoplasmic dissociation, RNA splicing and proteolytic functions participate in the stimulation. Homogenization of all these activities leads to the generation and sustainable facilitation of the robust rhythm and response to the diurnal variations of the environment. The purpose of this chapter is to explain the physiological and molecular mechanisms of the circadian clocks of plants, including biochemistry, and to demonstrate the function/role of the circadian clock in metabolic, physiological processes and plant behavior. © 2022 by Nova Science Publishers, Inc.
Red and blue light-mediated physiological and metabolic insights in Artemisia annua L.
(Elsevier B.V., 2024) Nidhi Rai; Naushad Ansari; Apoorva; Sabitri Kumari; Sneha Singh; Pajeb Saha; Mansi Singh Bisen; Shashi Pandey-Rai
The impact of quality of light on plant growth and development has been extensively studied. However, the interplay between photosynthesis and metabolic regulation in Artemisia annua remains largely unexplored. To address this gap, we investigated how various light qualities; monochromatic red (R), blue (B), a 1:1 red-blue combination (RB), and broad-spectrum white light (W); affect physiological parameters, photosynthetic activity, and metabolic processes. Plants were exposed to these light conditions at a photosynthetic photon flux density (PPFD) of 200 µmol·m⁻²·s⁻¹ for 10 days. Exposure to different light treatments resulted in significant changes in morphological attributes, chlorophyll and carotenoid content, stomatal conductance, intercellular CO₂ concentration, and transpiration rates. DPPH-scavenging activity and ascorbic acid levels increased under RB and B light, with increments of 20.76 %–25.6 % and 23 %–43.29 %, respectively, compared to W light. Gas chromatography-mass spectrometry (GC-MS) analysis showed the highest monoterpene concentration (36 %) under B light, followed by RB light (31 %), R light (28 %), and W light (27 %). Further, High-resolution mass spectrometry (HRMS) indicated elevated levels of flavonoids, terpenes, phenolics, and other organic compounds in RB light-exposed plants, with B light showing the following highest levels. Additionally, vital photosynthesis-regulating genes such as LHCII, CAO, TK, PsbA, PsaB, PsbD, RbcL, ndhB, RbcS, PetB, PetD, AtpA, and FBP demonstrated significant upregulation under various light conditions. Genes involved in artemisinin biosynthesis, including HMGS, MK, MCT, MPDC, CYP71AV1, and 1,8-cineol synthase, showed increases of 38.4 %–13.3 %, 20.4 %–22.4 %, 29.5 %–37.5 %, 15 %–16 %, 43 %–68 %, and 93.4 %–106.5 %, respectively, in response to B and RB light. These findings underscore the complex influence of various light qualities on the metabolic pathways of A. annua, providing a basis for future research. © 2024 Elsevier B.V.
Short-duration UV-B exposure mitigates salinity stress in Withania somnifera (L.) Dunal and boosts secondary metabolite production
(Elsevier B.V., 2025) Sneha Singh; Pajeb Saha; Sabitri Kumari; Jyotiraj Upadhyay; S. P. Rai
Withania somnifera is a widely valued medicinal plant traditionally cultivated in arid and semi-arid regions of India, where salt stress and rising UV-B radiation pose growing threats to its productivity and pharmacological quality of different metabolites. While the individual impacts of salinity and UV-B stress have been extensively studied, their interactive effects and potential for cross-tolerance in W. somnifera remain unexplored. In this study, we investigated the morphophysiological, biochemical, and metabolic responses of W. somnifera under salt (50–200 mM NaCl), UV-B (1–4 h), and combined exposure. Salt stress significantly reduced plant height, shoot biomass, photosynthetic efficiency (Fv/fm), and pigment content, while inducing oxidative damage. UV-B exposure alone enhanced relative water content, stimulated antioxidant enzyme activities (SOD, CAT, APX, and GR), and promoted the accumulation of secondary metabolites. Under combined salt and UV-B exposure, plants exhibited further amplified responses wherein antioxidant enzyme activities remained elevated while lipid peroxidation levels decreased compared to salt stress alone, suggesting reduced oxidative damage. Due to short-term UV-B exposure, metabolite profiling via high-resolution mass spectrometry revealed a synergistic enhancement in the accumulation of key secondary metabolites, particularly withanolides, flavonoids and triterpenoids, alongside the unique induction of stress-responsive compounds such as betaine and arjungenin. These findings suggest that short-duration UV-B exposure synergistically interacts with salt stress, intensifying redox activity and metabolic reprogramming to reinforce the plant's adaptive capacity. This work provides a foundation for integrating UV-B-based agronomic strategies in saline-prone regions to boost both stress resilience and the commercial phytochemical yield of W. somnifera. © 2025 Elsevier B.V.
Unlocking the industrial potential of Withania somnifera (L.) Dunal: A varietal comparison of morphology, microstructure, and metabolomic profiles
(Elsevier Ltd, 2025) Sneha Singh; Pajeb Saha; Sabitri Kumari; Nidhi Rai; S. P. Rai
To address the lack of publications on the metabolic profiling of W. somnifera varieties for industrial and pharmaceutical uses, we conducted a comprehensive analysis of the phytochemistry in three ashwagandha varieties- Red (R), Wild (W), and Pratap (P)- with a focus on their distinctive traits and potential commercial applications. Our research involved studies on germination, morphological assessments, and tissue culture experiments to understand growth potential and physical traits. Additionally, microscopic examinations of leaf structures and advanced techniques such as Raman spectroscopy and high-resolution mass spectrometry were used to analyse their biochemical and metabolite profiles. R exhibited a 101.5 % increase in total biomass in the field, while W showed the most vigorous in-vitro growth. The P variety had a high density of glandular trichomes, crucial for secondary metabolite production. Raman analysis revealed Withaferin A was most abundant in R, and phenylalanine was highest in P. HRMS results indicated comparable levels of terpenes in W and P, with P having higher fatty acids and steroids, known for skincare benefits. Peptides and amines were similarly high in R and W, supporting their therapeutic uses. These comprehensive plans revealed notable differences in the chemical profiles of the three varieties, emphasizing their potential for various industrial applications. This study not only adds to the understanding of the phytochemical diversity within W. somnifera but also further enables the improvement of the efficiency of cultivation and processing techniques for better medicinal and commercial outcomes. © 2025 Elsevier Ltd
Unravelling triterpenoid biosynthesis in plants for applications in bioengineering and large-scale sustainable production
(Elsevier B.V., 2023) Sneha Singh; Apoorva; Pajeb Saha; Nidhi Rai; Sabitri Kumari; Shashi Pandey-Rai
Plants are major factories for the biosynthesis of valuable bioactive compounds having pharmaceutical applications. These phytocompounds are synthesised via the diversion of primary metabolites toward secondary metabolic pathways. The most varied class of metabolites are triterpenoids that are biosynthesized through the MVA-MEP pathways, leading to the production of oxidosqualene followed by cyclization, and enzymatic modifications. Triterpenoids play a significant role in growth, development, reproductive behaviour, plant adaptation, and plant-to-plant communication. Various signals, through the signal transduction mechanism, are transmitted through receptors from cell to cell by a series of molecular events to initiate/ activate the cascade of the triterpenoid biosynthesis network. In this review, different naturally occurring classes of triterpenoids with their medicinal potential have been summarized. Further, this review provides insight into the current status of its synthesis through heterologous gene expression, structure elucidation, biosynthetic regulation via transcriptional regulation, and miRNAs. Recently, triterpenoids are in demand due to their variety of pharmacological importance which requires a fast rate of production. Furthermore, to ramp up the synthesis of these vital triterpenoids, the applications of modern bioengineering technologies and green nanoparticle synthesis, have been also highlighted here, offering sustainable alternatives for their large-scale production. © 2023 Elsevier B.V.