Browsing by Author "Tyagi, Shivi"

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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.
Expression of TaNCL2-A ameliorates cadmium toxicity by increasing calcium and enzymatic antioxidants activities in arabidopsis
(Elsevier B.V., 2023) Shumayla; Tyagi, Shivi; Sharma, Yashraaj; Madhu; Sharma, Alok; Pandey, Ashutosh; Singh, Kashmir; Upadhyay, Santosh Kumar
Cadmium (Cd) is a heavy metal that occurs naturally in the environment and is toxic to both animals and plants. The impact of Cd toxicity is shown to be reduced by the exogenous application of calcium (Ca) in crop plants. The sodium/calcium exchanger-like (NCL) protein is involved in Ca enrichment in the cytoplasm by transporting it from the vacuole in the exchange of cytosolic sodium (Na). However, it has not been utilized to ameliorate the Cd toxicity, to date. An elevated expression of TaNCL2-A gene in the root and shoot tissues of bread wheat seedlings, and a higher growth rate of recombinant yeast cells, suggested its role in Cd stress response. The TaNCL2-A expressing transgenic Arabidopsis lines exhibited significant Cd tolerance with increased Ca (∼10-fold) accumulation. The proline content and antioxidant enzymes activities were increased while oxidative stress-related molecules such as H2O2 and MDA were reduced in the transgenic lines. In addition, the growth and yield parameters of transgenic lines such as seed germination rate, root length, leaf biomass, leaf area index, rosette diameter, leaf length and width, and silique count, along with various physiological indicators like chlorophyll, carotenoid, and relative water contents were also improved in comparison to the control plants. Further, the transgenic lines exhibited significant salinity and osmotic stress tolerance, as well. Taken together, these results suggested that the TaNCL2-A could mitigate Cd toxicity along with salinity and osmotic stress. This gene may also be utilized for phytoremediation and Cd sequestration in future studies.
Flavonols affect the interrelated glucosinolate and camalexin biosynthetic pathways in Arabidopsis thaliana
(Oxford University Press, 2024) Naik, Jogindra; Tyagi, Shivi; Rajput, Ruchika; Kumar, Pawan; Pucker, Boas; Bisht, Naveen C.; Misra, Prashant; Stracke, Ralf; Pandey, Ashutosh
Flavonols are structurally and functionally diverse biomolecules involved in plant biotic and abiotic stress tolerance, pollen development, and inhibition of auxin transport. Despite the ubiquitous nature and multifunctionality of flavonols in land plants, their effects on global gene expression and signaling pathways are unclear. To explore the roles of flavonol metabolites in signaling, we performed comparative transcriptome and targeted metabolite profiling of seedlings from the flavonol-deficient Arabidopsis (Arabidopsis thaliana) loss-of-function mutant flavonol synthase1 (fls1) with and without exogenous supplementation of flavonol derivatives (kaempferol, quercetin, and rutin). Our RNA-seq results indicated that flavanols modulate various biological and metabolic pathways, with significant alteration in camalexin and aliphatic glucosinolate synthesis. Flavonols negatively regulated camalexin biosynthesis but appeared to promote the accumulation of aliphatic glucosinolates via transcription factor–mediated upregulation of biosynthesis genes. Interestingly, upstream amino acid biosynthesis genes involved in methionine and tryptophan synthesis were altered under flavonol deficiency and exogenous supplementation. Quercetin treatment significantly upregulated aliphatic glucosinolate biosynthesis genes compared to kaempferol and rutin. In addition, expression and metabolite analysis of the transparent testa7 mutant, which lacks hydroxylated flavonol derivatives, clarified the role of quercetin in the glucosinolate biosynthesis pathway. This study elucidates the molecular mechanisms by which flavonols interfere with signaling pathways, their molecular targets, and the multiple biological activities of flavonols in plants.
The R2R3-MYB gene family in Cicer arietinum: genome-wide identification and expression analysis leads to functional characterization of proanthocyanidin biosynthesis regulators in the seed coat
(Springer Nature Publishing AG, 2022) Rajput, Ruchika; Tyagi, Shivi; Naik, Jogindra; Pucker, Boas; Stracke, Ralf; Pandey, Ashutosh
Chickpea (Cicer arietinum) is among the eight oldest crops and has two main types, i.e., desi and kabuli, whose most obvious difference is the color of their seeds. We show that this color difference is due to differences in proanthocyanidin content of seed coats. Using a targeted approach, we performed in silico analysis, metabolite profiling, molecular, genetic, and biochemical studies to decipher the transcriptional regulatory network involved in proanthocyanidin biosynthesis in the seed coat of C. arietinum. Based on the annotated C. arietinum reference genome sequence, we identified 119 typical CaMYB encoding genes, grouped in 32 distinct clades. Two CaR2R3-MYB transcription factors, named CaPAR1 and CaPAR2, clustering with known proanthocyanidin regulators (PARs) were identified and further analyzed. The expression of CaPAR genes correlated well with the expression of the key structural proanthocyanidin biosynthesis genes CaANR and CaLAR and with proanthocyanidin levels. Protein–protein interaction studies suggest the in vivo interaction of CaPAR1 and CaPAR2 with the bHLH-type transcription factor CaTT8. Co-transfection analyses using Arabidopsis thaliana protoplasts showed that the CaPAR proteins form a MBW complex with CaTT8 and CaTTG1, able to activate the promoters of CaANR and CaLAR in planta. Finally, transgenic expression of CaPARs in the proanthocyanidin-deficient A. thaliana mutant tt2-1 leads to complementation of the transparent testa phenotype. Taken together, our results reveal main components of the proanthocyanidin regulatory network in C. arietinum and suggest that CaPARs are relevant targets of genetic engineering toward improved agronomic traits.
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.
TaGPX1-D overexpression provides salinity and osmotic stress tolerance in Arabidopsis
(Elsevier B.V., 2023) Tyagi, Shivi; Shumayla; Sharma, Yashraaj; Madhu; Sharma, Alok; Pandey, Ashutosh; Singh, Kashmir; Upadhyay, Santosh Kumar
Glutathione peroxidases (GPXs) are known to play an essential role in guarding cells against oxidative stress by catalyzing the reduction of hydrogen peroxide and organic hydroperoxides. The current study aims functional characterization of the TaGPX1-D gene of bread wheat (Triticum aestivum) for salinity and osmotic stress tolerance. To achieve this, we initially performed the spot assays of TaGPX1-D expressing yeast cells. The growth of recombinant TaGPX1-D expressing yeast cells was notably higher than the control cells under stress conditions. Later, we generated transgenic Arabidopsis plants expressing the TaGPX1-D gene and investigated their tolerance to various stress conditions. The transgenic plants exhibited improved tolerance to both salinity and osmotic stresses compared to the wild-type plants. The higher germination rates, increased antioxidant enzymes activities, improved chlorophyll, carotenoid, proline and relative water contents, and reduced hydrogen peroxide and MDA levels in the transgenic lines supported the stress tolerance mechanism. Overall, this study demonstrated the role of TaGPX1-D in abiotic stress tolerance, and it can be used for improving the tolerance of crops to environmental stressors, such as salinity and osmotic stress in future research.
Targeted metabolite profiling of five cultivars of Vitis vinifera L. fruits
(American Chemical Society, 2021) Alok, Anshu; Tyagi, Shivi; Singh, Kashmir; Pandey, Ashutosh
Grapes (Vitis vinifera L.) are a very popular fruit and are produced around the world. They are consumed as a fresh ripe fruit, dried fruit, juice, and processed product such as wine and are a good source of human nutrition. We aimed to investigate and analyze the nutritional and phytochemical components of grape cultivars, mostly cultivated in different regions of India. The targeted metabolic profiling of these cultivars was examined. A total of 58 metabolites, including three major sugars, nine organic acids, 14 amino acids, nine vitamins, and 23 phenolic compounds, were quantified in ripe berries of these grapes. Mineral quantification showed that these varieties contain major elements (K, Mg, and Ca) and minor elements (Mn, Fe, Zn, Cu, and Na). Principal component analysis showed that the contents of sugars, organic acids, and phenolic compounds are almost similar in cultivars FS and BJ, whereas the vitamin contents are nearly similar in TS and GS. Overall, these findings reveal that there is a differential in the accumulated content of primary and specialized metabolites as well as minerals in ripe fruits, providing a source for commercial value and food industry applications.