Browsing by Author "Singh, Samar"

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CaLAP1 and CaLAP2 orchestrate anthocyanin biosynthesis in the seed coat of Cicer arietinum
(Springer Nature Publishing AG, 2024) Singh, Samar; Pal, Lalita; Rajput, Ruchika; Chhatwal, Himani; Singh, Nidhi; Chattopadhyay, Debasis; Pandey, Ashutosh
The seed coat color is a major economic trait in leguminous crop chickpea (Cicer arietinum). Anthocyanins and proanthocyanidins (PAs) are two classes of flavonoids that mainly contribute to the flower, seed coat and color of Desi chickpea cultivars. Throughout the land plant lineage, the accumulation of anthocyanins and PAs is regulated by MYB and bHLH transcription factors (TFs), which form an MBW (MYB, bHLH, and WD40) complex. Here, we report two R2R3-MYB TFs in chickpea belonging to the anthocyanin-specific subgroup-6, CaLAP1 (Legume Anthocyanin Production 1), and CaLAP2 (Legume Anthocyanin Production 2), which are mainly expressed in the flowers and developmental stages of the seeds. CaLAP1 and CaLAP2 interact with TT8-like CabHLH1 and WD40, forming the MBW complex, and bind to the promoter sequences of anthocyanin- and PA biosynthetic genes CaCHS6, CaDFR2, CaANS, and CaANR, leading to anthocyanins and PA accumulation in the seed coat of chickpea. Moreover, these CaLAPs partially complement the anthocyanin-deficient phenotype in the Arabidopsis thaliana sextuple mutant seedlings. Overexpression of CaLAPs in chickpea resulted in significantly higher expression of anthocyanin and PA biosynthetic genes leading to a darker seed coat color with higher accumulation of anthocyanin and PA. Our findings show that CaLAPs positively modulate anthocyanin and PA content in seed coats, which might influence plant development and resistance to various biotic and abiotic stresses.
Climate change impact on human health
(CABI, 2024) Singh, Samar; Chhatwal, Himani; Pandey, Ashutosh
Variations in environmental conditions caused by natural or anthropogenic activities have been exhibiting their impacts on climate change in the form of heat waves, drought, acid rain, floods, and storms throughout the decades. The resulting climate change has perturbated the interrelated threats to the ecosystem. Climate change affects human health, causing mental illness, undernutrition, and cardiovascular, respiratory, and infectious diseases. This outcome is observed in terms of worldwide disturbance in social dynamics such as health status, socioeconomic status, and public health infrastructure. This chapter explores the adverse climate conditions and highlights footprints on human health. Strategies to reduce the catastrophic impact of climate change on humans have been discussed in the latter sections.
Cytokinin-mediated repression of anthocyanin biosynthesis in banana fruits
(John Wiley & Sons, 2025) Rajput, Ruchika; Tyagi, Shivi; Anchal, Kumar; Singh, Samar; Laxmi, Ashverya; Misra, Prashant; Pandey, Ashutosh
Anthocyanins are pigments responsible for vibrant plant colors and play vital roles in plant physiology. This study compares two banana cultivars, Grand Naine (GN) and Red Banana (RB), which exhibit significant differences in anthocyanin pigmentation. Transcriptomic profiling of peel (PL) and pulp (PP) tissues revealed cytokinin-responsive type-B response regulators (RRs), MaRR_B9 and MaRR_B12, as key modulators of anthocyanin biosynthesis. Cytokinin treatment of PP tissues increased the expression of MaRR_B9 and MaRR_B12, while significantly reducing the expression of dihydroflavanol reductase (MaDFR1, MaDFR2) and anthocyanidin synthase (MaANS) genes along with anthocyanin content. Through a combination of physiological, molecular, and biochemical analyses, we demonstrate that MaRR_B9 and MaRR_B12 exert direct regulatory control over key structural genes of anthocyanin biosynthesis, MaDFRs and MaANS. Additionally, a type B-RRs motif (AGATT) was identified in the promoter regions of MaDFR2 and MaANS, suggesting that MaRRs might directly regulate the transcription of MaDFR2 and MaANS. MaRR_B9 and MaRR_B12 interact with the promoters of MaDFR2 and MaANS, repressing these genes in vivo. Overexpression of MaRR_B9 and MaRR_B12 in banana fruits leads to a reduction in anthocyanin content, notably the cyanidin derivative, accompanied by altered expression patterns of MaDFRs and MaANS. Thus, the present study identifies MaRR_B9 and MaRR_B12 as novel regulators of anthocyanin biosynthesis in banana and provides further evidence that the cytokinin regulatory network modifies anthocyanin accumulation in plants. In conclusion, our findings reveal new molecular targets, in the form of MaRRs, for the genetic optimization aimed at enhancing anthocyanin content, stress resilience, and nutritional value in crop plants.
Deciphering the complexity of terpenoid biosynthesis and its multi-level regulatory mechanism in plants
(Springer Nature Publishing AG, 2024) Singh, Samar; Chhatwal, Himani; Pandey, Ashutosh
Terpenoids are one of the essential plant metabolites which are known to play vital roles in plants' primary growth and development including protection from biotic and abiotic stresses. They have huge structural diversity and are known to provide various health benefits, flavors, fragrances, essential oils, cosmetics, pigments, insecticides, etc. The biosynthesis of terpenoids by mevalonic acid (MVA) and methylerythritol pathway (MEP) occurs inside the cytoplasm and the chloroplast, respectively. Here, we provide a comprehensive overview of synthesis, metabolic, and regulatory pathways of terpenoid, their different classes and ecological roles. We also discuss in detail the key transcription factors (TFs) like WRKY, AP2/ERF, bHLH, MYB, NAC, and bZIP which reprogram and modulate the terpenoid pathway in plants. It also includes the post-transcriptional and post-translational modifications of these pathways. The post-transcriptional regulation by microRNA plays a critical role in the synthesis and regulation of the terpenoid. MAP kinases also regulate the stability of biosynthetic enzymes and transcription factors to regulate terpenoid biosynthesis. High-throughput sequencing technology and functional genomics have further strengthened our understanding of this pathway and associated regulatory genes which control it. As a future perspective, modifying these transcription factors via various strategies holds promise for improvement of agricultural crop plants in terms of nutritional enrichment, stress responsiveness, and resistance.
Genetics of plant organelles: Plastid and mitochondrial genomes
(Springer Nature Publishing AG, 2022) Singh, Samar; Naik, Jogindra; Pandey, Ashutosh
Plant organelles like chloroplasts and mitochondria are essential organelles serving critical functions like photosynthesis and respiration, respectively, in plants. While most of the processes and the components required by the functioning of these organelles are contributed by nuclear DNA, they have few of their own components encoded by their respective genome. Mitochondrial and chloroplast genomes give a real insight into the evolution of land plants, as evident by several studies. Few studies have successfully conducted gene transfer technology into these organelles’ genomes. Although extensive research on plant organelle genome is yet to be done, recent research has shown the probability of these organelles as a target of genome engineering. From targeting individual genes of their genome to incorporating new genes from other species, they hold promises to produce improved traits. Packaging of their genome, which varies significantly in various hierarchies of land and primitive plants, has also been studied in few plant species. This chapter summarizes the current studies and findings in the study of the organellar genome concerning their structure, organization, distribution, regulatory mechanism, and gene transfer technologies. This chapter provides an updated account of the evolution of these organelle genomes.
Heat-responsive MaHSF11 transcriptional activator positively regulates flavonol biosynthesis and flavonoid B-ring hydroxylation in banana (Musa acuminata)
(John Wiley & Sons, 2025) Naik, Jogindra; Rajput, Ruchika; Singh, Samar; Stracke, Ralf; Pandey, Ashutosh
Plant flavonols act primarily as ultraviolet radiation absorbers, reactive oxygen species scavengers, and phytoalexins, and they contribute to biotic and abiotic stress tolerance in plants. Banana (Musa acuminata), an herbaceous monocot and important fruit crop, accumulates flavonol derivatives in different organs, including the edible fruit pulp. Although flavonol content varies greatly in different organs, the molecular mechanisms involving transcriptional regulation of flavonol synthesis in banana are not known. Here, we characterized three SG7-R2R3 MYB transcription factors (MaMYBFA1, MaMYBFA2, and MaMYBFA3) and heat shock transcription factor (MaHSF11), to elucidate the molecular mechanism involved in transcriptional regulation of flavonol biosynthesis in banana. MaMYBFA positively regulates flavonol synthase 2 (MaFLS2) and downregulates MaFLS1. We show these transcription factors to be weak regulators of flavonol synthesis. Overexpression of MaHSF11 enhances flavonol contents, particularly that of myricetin, and promotes flavonol B-ring hydroxylation, which contributes to the diversity of flavonol derivatives. MaHSF11 directly interacts with the MaFLS1 and flavonoid 3',5'-hydroxylase1 (MaF3'5'H1) promoters, both in vitro and in vivo. MaHSF11 activates the expression of MaDREB1 directly, which is known to promote cold and chilling tolerance in banana fruit. Overall, our study elucidates a regulatory mechanism for flavonol synthesis in banana and suggests possible targets for genetic optimization to enhance nutritional value and stress responses in this globally important fruit crop.
Hotspots associated with climate change and food security risks
(CABI, 2024) Chhatwal, Himani; Singh, Samar; Pandey, Ashutosh
Climate change is an emerging problem, threatening nations at a global stage. Our knowledge about the impact of climate change on agriculture has grown over the past two decades, but recently, it has been found that its effects are even more deep-rooted. Anthropogenic and natural activities are increasing global temperatures at an alarming rate, affecting crop productivity. Extreme weather events will impact food supply, stability, and access. In the current times of increasing population, when wholesome food production is a global concern, climate change becomes an inevitable issue that no nation can escape from. This chapter highlights the major hotspots of the world which face an immediate threat from climate change. It also covers the perils of changing climate on the food production system and the adaptation strategies to overcome it. The need is to focus on developing immediate solutions to develop a sustainable food supply in the future.
TaCCS1-B expression modulates copper, enzymatic antioxidants and polyphenols contents and provides abiotic stress tolerance in transgenic Arabidopsis
(John Wiley & Sons, 2024) Tyagi, Shivi; Shumayla; Singh, Samar; Pandey, Ashutosh; Upadhyay, Santosh Kumar
Abiotic stress, including osmotic and salinity stress, significantly affects plant growth and productivity. Copper chaperone for superoxide dismutase (CCS) is essential for copper homeostasis and oxidative stress management. In this study, we investigated the role of the TaCCS1-B gene of bread wheat in enhancing stress tolerance in yeast and transgenic Arabidopsis. Expression of TaCCS1-B increased abiotic stress tolerance in recombinant yeast cells. Phenotypic analysis of Arabidopsis TaCCS1-B expressing lines demonstrated that they exhibited significantly higher germination rates, increased root length and better growth under osmotic and salinity stress than wild type. Additionally, the transgenic lines exhibited higher copper accumulation and enhanced photosynthetic pigments and proline level, coupled with reduced hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) contents. They also showed higher enzymatic antioxidants' activities, indicating reduced oxidative stress in transgenic lines, resulting in reduced flavonoid content. Gene expression analysis indicated modulated expression of stress-responsive genes in the transgenic lines under stress conditions. These findings suggested the role of TaCCS1-B in enhancing stress tolerance by improving copper homeostasis and regulating key stress-responsive genes. This study highlights the potential of TaCCS1-B for the development of better stress resilience crops, which is critical for sustaining agricultural productivity for food security under adverse environmental conditions.