Institutional Publications

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    Modulation of nitric oxide mediated by Phytoglobin1 plays a role in salinity tolerance via reduced nitro-oxidative stress in Arabidopsis
    (Elsevier B.V., 2026) Swain, Jagannath; Babuta, Priyanka; Pandey, Sonika; Samant, Sanjib Bal; Yadav, Reena; Manbir; Hebelstrup, Kim H.; Igamberdiev, Abir U.; Singla-Pareek, Sneh Lata; Pareek, Ashwani; Gupta, Kapuganti Jagadis
    Salinity is one of the major abiotic stresses that induces nitro-oxidative stress, which severely diminishes plant growth, development, and survival by altering various metabolic pathways. Phytoglobin (Pgb) is a nitric oxide (NO) scavenger that plays an important role in various stresses. However, the role of differential levels of phytoglobin1 in regulation of salinity stress induced nitro-oxidative stress in plants is not known. Here we characterized the role of Pgb-mediated NO in salinity tolerance by regulation of nitro-oxidative stress using Pgb1 overexpressing (Pgb1-OE) and silencing lines (pgb1-AS) of Arabidopsis. We found that imposing salinity leads to enhanced expression of Pgb1. NO measurement by both chemiluminescence and DAF-FM-DA suggested that salinity stress induces NO production. Pgb1-OE lines showed reduced levels of NO which is accompanied by reduced ROS, superoxide and H2O2 levels. On the contrary, pgb1-AS lines showed increased NO and ROS under salt stress. Further, gene expression analysis revealed an elevated expression of antioxidant genes in Pgb1-OE line in comparison to WT and pgb1-AS lines under salinity stress. Pgb1-OE lines showed enhanced survival which is correlated with reduced peroxynitrite and tyrosine nitration and opposing effect was observed in pgb1-AS lines along with increased cell death. Taken together, our study revealed that modulation of Pgb1 enhances tolerance to salinity-induced nitro-oxidative stress.
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    Measurement of reactive oxygen species and nitric oxide from tomato plants in response to abiotic and biotic stresses
    (Springer Nature Publishing AG, 2024) Samant, Sanjib Bal; Manbir; Rekha; Swain, Jagannath; Singh, Pooja; Kumari, Aprajita; Gupta, Kapuganti Jagadis
    Nitric oxide (NO) is a free radical molecule that has been known to influence several cellular processes such as plant growth, development, and stress responses. NO together with reactive oxygen species (ROS) play a role in signaling process. Due to extremely low half-life of these radicals in cellular environment, it is often difficult to precisely monitor them. Each method has some advantages and disadvantages; hence, it is important to measure using multiple methods. To interpret the role of each signaling molecule in numerous biological processes, sensitive and focused methods must be used. In addition to this complexity, these Reactive Oxygen Species (ROS) and NO react with each other leads to nitro-oxidative stress in plants. Using tomato as a model system here, we demonstrate stepwise protocols for measurement of NO by chemiluminescence, DAF fluorescence, nitrosative stress by western blot, and ROS measurement by NBT and DAB under stress conditions such as osmotic stress and Botrytis infection. While describing methods, we also emphasized on benefits, drawbacks, and broader applications of these methods.
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    Alternative oxidase plays a role in minimizing ROS and RNS produced under salinity stress in Arabidopsis thaliana
    (John Wiley & Sons, 2022) Manbir; Singh, Pooja; Kumari, Aprajita; Gupta, Kapuganti Jagadis
    Under stress conditions, the overproduction of different reactive oxygen species (ROS) and reactive nitrogen species (RNS) causes imbalance in the redox homeostasis of the cell leading to nitro-oxidative stress in plants. Alternative oxidase (AOX) is a conserving terminal oxidase of the mitochondrial electron transport chain, which can minimize the ROS. Still, the role of AOX in the regulation of RNS during nitro-oxidative stress imposed by salinity stress is not known. Here, we investigated the role of AOX in minimizing ROS and RNS induced by 150 mM NaCl in Arabidopsis using transgenic plants overexpressing (AOX OE) and antisense lines (AOX AS) of AOX. Imposing NaCl treatment leads to a 4-fold enhanced expression of AOX accompanied by enhanced AOX capacity in WT Col-0. Further AOX-OE seedlings displayed enhanced growth compared with the AOX-AS line under stress. Examination of NO levels by DAF-FM fluorescence and chemiluminescence revealed that AOX overexpression leads to reduced levels of NO. The total NR activity was elevated under NaCl, but no significant change was observed in wild-type (WT), AOX OE, and AS lines. The total ROS, superoxide, H2O2 levels, and lipid peroxidation were higher in the AOX-AS line than in WT and AOX-OE lines. The peroxynitrite levels were also higher in the AOX-AS line than in WT and AOX-OE lines; further, the expression of antioxidant genes was elevated in AOX-AS. Taken together, our results suggest that AOX plays an important role in the mitigation of ROS and RNS levels and enhances plant growth, thus providing tolerance against nitro-oxidative stress exerted by NaCl.
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    Phytoglobin-NO cycle and AOX pathway play a role in anaerobic germination and growth of deepwater rice
    (John Wiley & Sons, 2021) Kumari, Aprajita; Singh, Pooja; Kaladhar, Vemula Chandra; Manbir; Paul, Debarati; Pathak, Pradeep Kumar; Gupta, Kapuganti Jagadis
    An important and interesting feature of rice is that it can germinate under anoxic conditions. Though several biochemical adaptive mechanisms play an important role in the anaerobic germination of rice but the role of phytoglobin-nitric oxide cycle and alternative oxidase pathway is not known, therefore in this study we investigated the role of these pathways in anaerobic germination. Under anoxic conditions, deepwater rice germinated much higher and rapidly than aerobic condition and the anaerobic germination and growth were much higher in the presence of nitrite. The addition of nitrite stimulated NR activity and NO production. Important components of phytoglobin-NO cycle such as methaemoglobin reductase activity, expression of Phytoglobin1, NIA1 were elevated under anaerobic conditions in the presence of nitrite. The operation of phytoglobin-NO cycle also enhanced anaerobic ATP generation, LDH, ADH activities and in parallel ethylene levels were also enhanced. Interestingly nitrite suppressed the ROS production and lipid peroxidation. The reduction of ROS was accompanied by enhanced expression of mitochondrial alternative oxidase protein and its capacity. Application of AOX inhibitor SHAM inhibited the anoxic growth mediated by nitrite. In addition, nitrite improved the submergence tolerance of seedlings. Our study revealed that nitrite driven phytoglobin-NO cycle and AOX are crucial players in anaerobic germination and growth of deepwater rice.