Browsing by Author "Misra, Prashant"

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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.
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.
Gene pyramiding in transgenic plant development: Approaches and challenges
(Springer Nature Publishing AG, 2023) Rajput, Ruchika; Naik, Jogindra; Misra, Prashant; Trivedi, Prabodh Kumar; Pandey, Ashutosh
Climate change leads to frequent alterations in environmental factors with a reciprocal impact on crop productivity. Over the last few decades, various approaches have been used for producing more stress-tolerant and climate-flexible crops. Genetic engineering is one of the approaches used to modify multiple characters or to improve more than one agronomic trait in plants. These instances simultaneously demand simultaneous genetic manipulation of multiple genes, necessitating stacking or pyramiding of multiple genes as compared to single-gene manipulations, and the genetic engineering of plants using multiple genes is technically challenging. In the last two decades, considerable progress has been made with respect to the development and application of the methods for gene pyramiding in transgenic context. The conventional methods of gene stacking include the crossing of individual transgenic plants, co-transformation using multiple plant expression constructs, transformation with single constructs carrying multiple transgenes as well as with the constructs carrying polycistronic transgenes. These methods have been instrumental for gene stacking in several commercialized crops. The tools of targeted genome editing (ZFN, TALEN, and CRISPR) that carry out precise genetic modifications, have opened new avenues in the area of crop biotechnology for defending plants against various stresses. The present review covers the current status of biotechnological techniques used to combat biotic and abiotic stresses in crop plants and describes multiple associated challenges.
Molecular components associated with the regulation of flavonoid biosynthesis
(Elsevier B.V., 2022) Naik, Jogindra; Misra, Prashant; Trivedi, Prabodh Kumar; Pandey, Ashutosh
Flavonoids exhibit amazing structural diversity and play different roles in plants. Besides, these compounds have been associated with several health benefits in humans. Several exogenous and endogenous cues, for example, light, temperature, nutrient status, and phytohormones have been reported as modulators of biosynthesis and accumulation of flavonoids. Thus, multiple hormones and stress-related signaling pathways are involved in the regulation of gene expression associated with this pathway. The transcriptional regulators belonging to the MYB and bHLH family transcription factors are well documented as the direct regulators of the structural genes associated with flavonoid biosynthesis. Recent studies also suggest that some of these factors are regulated by molecular components involved in stress and hormone signaling pathways. Adapter proteins for transcriptional activation or repression via recruitment of co-activators and co-repressors, respectively, E2 ubiquitin ligases, miRNA processing complex, and DNA methylation/demethylation factors have been recently discovered in various plants to play key roles in fine-tuning flavonoids synthesis. In the present review, we aim to provide comprehensive information about the role of different factors in the regulation of flavonoid biosynthesis. Besides, we describe the potential upstream regulators involved in the regulation of flavonoid biosynthesis within the context of available information. To sum up, the present review furnishes an updated account of signal transduction pathways modulating the biosynthesis of flavonoids.
Two homeologous MATE transporter genes, NtMATE21 and NtMATE22, are involved in the modulation of plant growth and flavonol transport in Nicotiana tabacum
(Oxford University Press, 2022) Gani, Umar; Nautiyal, Abhishek Kumar; Kundan, Maridul; Rout, Biswaranjan; Pandey, Ashutosh; Misra, Prashant
Multidrug and toxic compound extrusion (MATE) family has been implicated in the transport of a diverse range of molecules, including specialized metabolites. In Nicotiana tabacum, only a limited number of MATE transporters have been functionally characterized, and no MATE transporter has been studied in the context of flavonoid transport in this plant species so far. Here in the present study, we characterize two homeologous MATE genes, NtMATE21 and NtMATE22, and demonstrate their role in flavonol transport and in plant growth and development. The expression of these two genes was reported to be up-regulated in trichomes as compared to the trichome-free leaf. The transcript levels of NtMATE21 and NtMATE22 were found to be higher in flavonol over-producing tobacco transgenic lines as compared to wild type (WT) tobacco. The two transporters were demonstrated to be localized to the plasma membrane. Genetic manipulation of NtMATE21 and NtMATE22 led to altered growth phenotypes and modulated flavonol contents in N. tabacum. The GUS and GFP fusion transgenic lines of promoter regions suggested that NtMATE21 and NtMATE22 exclusively express in the trichome heads in the leaf tissue and petals. Moreover, in transient transactivation assay, NtMYB12, a flavonol-specific MYB transcription factor, was found to transactivate the expression of NtMATE21 and NtMATE22 genes. Together, our results strongly suggest the involvement of NtMATE21 and NtMATE22 in flavonol transport as well as in the regulation of plant growth and development.