Publications of NIPGR Scientists
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Item UV‐B activates a ‘group A’ mitogen activated protein kinase in Oryza sativa(Springer, 2016) Wankhede, Dhammaprakash Pandhari; Singh, Pallavi; Jaggi, Monika; Rao, Kudupudi Prabhakara; Raina, Susheel Kumar; Sinha, Alok KrishnaIncreased level of Ultra violet-B radiation at earth’s surface has several deleterious consequences for plants and ecosystems. Higher UV-B level affects crop plants in several ways and also gives penalty in terms of crop yield. With changing climatic conditions it is crucial to elucidate signal transduction pathway involved in UV-B stress. Here, involvement of mitogen activated protein kinases (MAPKs) in UV-B stress was investigated in rice (Oryza sativa). Transcripts profiling of all 15 rice MAPKs have shown UV-B induced expressions of a few MAPK genes including OsMPK3, OsMPK6, OsMPK4, OsMPK17-1, OsMPK17-2, OsMPK20-1, OsMPK20-4 and OsMPK20-5. In-gel kinase assay as well as immuno-kinase assay showed activation of single MAPK of size ~45 kDa in response to UV-B treatment. Further UV-B responsive activity of rice MAPKs, OsMPK3, OsMPK4 and OsMPK6 was checked using antibodies for the respective orthologs in Arabidopsis which indicated activation of OsMPK3 in UV-B stress. Additionally, GST: OsMPK3 protein showed UV responsive phosphorylation when incubated with crude protein extract from UV exposed plants in an in-vitro phosphorylation assay. These results indicate activation of OsMPK3 in UV-B stress. Further, possible involvement of UV-B responsive OsWRKY89 downstream of MAPK cascade was studied. It was observed that staurosporin and other specific chemical inhibitors of MAPK could attenuate UV-B induced expression of OsWRKY89. OsMPK3 was also found to interact with OsWRKY89 in yeast two-hybrid assay, although the interaction was weak in nature. The present work gives an account of MAPKs in UV-B stress in rice.Item Mitogen-activated protein kinases in abiotic stress tolerance in crop plants: "-omics" approaches(Wiley-VCH Verlag GmbH & Co., 2013) Jaggi, Monika; Gupta, Meetu; Tuteja, Narendra; Sinha, Alok KrishnaPlants, in order to grow and survive, need to counter a plethora of stresses, both biotic and abiotic. During the process of evolution, plants have developed sophisticated mechanisms to perceive these stresses and transduce them down to the nucleus for appropriate cellular adjustment. Phosphorylation of proteins is one of the important mechanisms for controlling many fundamental cellular processes in all living organisms. A network of mitogen-activated protein kinases (MAPKs) is an evolutionarily conserved phosphorelay cascade among animals, plants, and yeasts that transduces a variety of signals from cell surfaces to the nucleus. This unique protein cascade is also involved in the development and survival of the plants. This cascade consists essentially of three components, a MAPK kinase kinase (MAPKKK), a MAPK kinase (MAPKK), and a MAPK connected to each other by the event of phosphorylation. Signaling through MAP kinase cascade can lead to cellular responses including cell division and differentiation as well as responses to various stresses. In plants, MAP kinases are represented by multigene families and are involved in efficient transmission of specific stimuli and also involved in the regulation of the antioxidant defense system in response to stress signaling. In this chapter, we summarize and investigate the participation of MAPKs as possible mediators of various abiotic stresses in plants. We also focus on recent progress in integrated transcriptomics, proteomics, and metabolomics analyses of MAPK signaling pathway that regulates plant physiological processes during abiotic stress responses. We also deal with the limitations and future prospects of these “-omics” approaches.Item CrMPK3, a mitogen activated protein kinase from Catharanthus roseus and its possible role in stress induced biosynthesis of monoterpenoid indole alkaloids(BMC, 2012) Raina, Susheel Kumar; Wankhede, Dhammaprakash Pandhari; Jaggi, Monika; Singh, Pallavi; Jalmi, Siddhi Kashinath; Raghuram, Badmi; Sheikh, Arsheed Hussain; Sinha, Alok KrishnaMitogen activated protein kinase (MAPK) cascade is an important signaling cascade that operates in stress signal transduction in plants. The biologically active monoterpenoid indole alkaloids (MIA) produced in Catharanthus roseus are known to be induced under several abiotic stress conditions such as wounding, UV-B etc. However involvement of any signaling component in the accumulation of MIAs remains poorly investigated so far. Here we report isolation of a novel abiotic stress inducible Catharanthus roseus MAPK, CrMPK3 that may have role in accumulation of MIAs in response to abiotic stress.Item Ectopic overexpression of vacuolar and apoplastic Catharanthus roseus peroxidases confers differential tolerance to salt and dehydration stress in transgenic tobacco(Springer Science, 2012) Kumar, Santosh; Jaggi, Monika; Sinha, Alok KrishnaCrPrx and CrPrx1 are class III peroxidases previously cloned and characterized from Catharanthus roseus. CrPrx is known to be apoplastic in nature, while CrPrx1 is targeted to vacuoles. In order to study their role in planta, these two peroxidases were expressed in Nicotiana tabacum. The transformed plants exhibited increased peroxidase activity. Increased oxidative stress tolerance was also observed in transgenics when treated with H(2)O(2) under strong light conditions. However, differential tolerance to salt and dehydration stress was observed during germination of T1 transgenic seeds. Under these stresses, the seed germination of CrPrx-transformed plants and wild-type plants was clearly suppressed, whereas CrPrx1 transgenic lines showed improved germination. CrPrx-transformed lines exhibited better cold tolerance than CrPrx1-transformed lines. These results indicate that vacuolar peroxidase plays an important role in salt and dehydration stress over cell wall-targeted peroxidase, while cell wall-targeted peroxidase renders cold stress tolerance.Item Mitogen-activated protein kinase signaling in plant under abiotic stress(Landes Bioscience, 2011) Sinha, Alok Krishna; Jaggi, Monika; Raghuram, Badmi; Tuteja, NarendraMitogen-activated protein kinase cascade is evolutionarily conserved signal transduction module involved in transducing extracellular signals to the nucleus for appropriate cellular adjustment. This cascade consists essentially of three components, a MAPK kinase kinase (MAPKKK), a MAPK kinase (MAPKK) and a MAPK connected to each other by the event of phosphorylation. These kinases play various roles in intra- and extra-cellular signaling in plants by transferring the information from sensors to responses. Signaling through MAP kinase cascade can lead to cellular responses including cell division, differentiation as well as responses to various stresses. MAPK signaling has also been associated with hormonal responses. In plants, MAP kinases are represented by multigene families and are involved in efficient transmission of specific stimuli and also involved in the regulation of the antioxidant defense system in response to stress signaling. In the current review we summarize and investigate the participation of MAPKs as possible mediators of various abiotic stresses in plants.Item Cloning and characterization of two new Class III peroxidase genes from Catharanthus roseus(Elsevier, 2011) Kumar, Santosh; Jaggi, Monika; Taneja, Jyoti; Sinha, Alok KrishnaWe report here the cloning and characterization of two new class III peroxidase genes, CrPrx3 and CrPrx4 from Catharanthus roseus. The full length cDNA of CrPrx3 is 1233 bp long encoding 330 amino acid residues. The CrPrx4 cDNA contains an ORF of 1055 bp, and encodes for 318 amino acids. Hypothetical 3-D structure model of CrPrx3 and CrPrx4 detected the presence of two Ca(2+) ion binding sites at proximal and distal end, and a heme group coordinate at central position. CrPrx3 and CrPrx4 are present in single copy number in C. roseus. Confocal scanning microscopy and phylogenetic analysis showed that CrPrx3 and CrPrx4 are apoplastic in nature. Phylogenetic analysis revealed that both genes have diverse expression patterns in a variety of plant tissues. Quantitative real-time PCR confirmed their maximum expression in stem tissues followed by flower tissue. The expression levels of CrPrx3 and CrPrx4 were down-regulated under salt and dehydration stress, respectively.Item Overexpression of an apoplastic peroxidase gene CrPrx in transgenic hairy root lines of Catharanthus roseus(Springer Science, 2011) Jaggi, Monika; Kumar, Santosh; Sinha, Alok KrishnaPeroxidases are a family of isoenzymes found in all higher plants and are known to be involved in a broad range of physiological processes. However, very little information is available concerning their role in Catharanthus roseus. The present study describes the impact of both overexpression and suppression of a peroxidase gene, CrPrx in C. roseus transgenic hairy root lines. Real-time PCR analysis in 35S-CrPrx and CrPrx-RNAi transgenic lines indicated differential transcript profile for peroxidases as well as for genes and regulators involved in MIA (monoterpenoid indole alkaloid) pathway of C. roseus. Comparative analysis revealed that MIA pathway genes showing elevated levels of expression in 35S-CrPrx transgenic lines showed a significant reduction in their transcript level in CrPrx-RNAi transgenic lines. Metabolite analysis detected higher levels of ajmalicine and serpentine accumulation in overexpressed lines. It was observed that all overexpressed transgenic lines produced more amount of H(2)O(2). These results indicate a role of CrPrx gene in the regulation of MIA pathway genes and regulators, thus affecting the production of specific alkaloids.Item Effect of loss of T-DNA genes on MIA biosynthetic pathway gene regulation and alkaloid accumulation in Catharanthus roseus hairy roots(Springer, 2010) Taneja, Jyoti; Jaggi, Monika; Wankhede, Dhammaprakash Pandhari; Sinha, Alok KrishnaHairy roots are generated by integration of T-DNA in host plant genome from root inducing (Ri) plasmid of Agrobacterium rhizogenes and have been utilized for production of secondary metabolites in different plant systems. In Catharanthus roseus, hairy roots are known to show different morphologies, growth patterns, and alkaloid contents. It is also known that during transformation, there is a differential loss of a few T-DNA genes. To decipher the effect of loss of T-DNA genes on the various aspects of hairy roots, ten hairy root clones were analyzed for the presence or absence of T-DNA genes and its implications. It was found that the loss of a few ORFs drastically affects the growth and morphological patterns of hairy roots. The absence of T(R)-DNA from hairy roots revealed increased transcript accumulation and higher alkaloid concentrations, whereas callusing among hairy root lines led to decreased transcript and alkaloid accumulation. Significantly higher expression of MIA biosynthetic pathway genes and low abundance of regulator transcripts in hairy root clones in comparison with non-transformed control roots were also observed. This study indicates that it is not only the integration of T-DNA at certain region of host plant genome but also the presence or absence of important ORFs that affects the expression patterns of MIA biosynthetic pathway genes, regulators, and accumulation of specific alkaloids.