Publications of NIPGR Scientists

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Author: search.filters.author.Singh, PoojaSubject: search.filters.subject.nitrite

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    Nitric oxide regulates mitochondrial biogenesis in plants
    (John Wiley & Sons, 2023) Kumari, Aprajita; Kaladhar, Vemula Chandra; Yadav, Nidhi; Singh, Pooja; Reddy, Kishorekumar; Gupta, Kapuganti Jagadis
    The site of nitric oxide (NO) production in mitochondrial cytochrome c oxidase and the role of NO in mitochondrial biogenesis are not known in plants. By imposing osmotic stress and recovery on Arabidopsis seedlings we investigated the site of NO production and its role in mitochondrial biogenesis. Osmotic stress reduced growth and mitochondrial number while increasing NO production. During the recovery phase the mitochondrial number increased and this increase was higher in wild type and the high NO-producing Pgb1 silencing line in comparison to the NO-deficient nitrate reductase double mutant (nia1/nia2). Application of nitrite stimulated NO production and mitochondrial number in the nia1/nia2 mutant. Osmotic stress induced COX6b−3 and COA6-L genes encoding subunits of COX. The mutants cox6b-3 and coa6-l were impaired both in NO production and mitochondrial number during stress to recovery suggesting the involvement of these subunits in nitrite-dependent NO production. Transcripts encoding the mitochondrial protein import machinery showed reduced expression in cox6b-3 and coa6-l mutants. Finally, COX6b-3 and COA6-L interacted with the VQ27 motif-containing protein in the presence of NO. The vq27 mutant was impaired in mitochondrial biogenesis. Our results suggest the involvement of COX derived NO in mitochondrial biogenesis.
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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.
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    The power of the phytoglobin-NO cycle in the regulation of nodulation and symbiotic nitrogen fixation
    (John Wiley & Sons, Inc., 2020) Singh, Pooja; Kumari, Aprajita; Foyer, Christine H.; Gupta, Kapuganti Jagadis
    Recent years have seen a large increase in our understanding of the multifaceted roles of nitric oxide (NO) in plant biology, particularly in the regulation of symbiotic interactions with soil microorganisms. NO serves key functions in the initiation and maintenance of legume–rhizobium symbiosis. Extensive molecular crosstalk between the host legume and the soil rhizobium results in the initiation of symbiosis and the establishment of a highly specialized organ called the nodule, which provides the conditions required for bacterial nitrogen fixation. Within the nodules, the rhizobium bacteria are housed in bacteroids, in which the oxygen is maintained at very low levels allowing the bacterial nitrogenase to function. This enzyme is oxygen sensitive (half maximal inhibitory concentration (IC50) oxygen for nitrogenase is 2.9 µM; Goldberg et al., 1987). Hence, a key feature of the nodule is the maintenance of a strong oxygen diffusion barrier, in which leghaemoglobin is used to transfer oxygen to the plant mitochondria to sustain respiration.
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    Nitric oxide accelerates germination via the regulation of respiration in chickpea
    (Oxford University Press, 2019) Pandey, Sonika; Kumari, Aprajita; Shree, Manu; Kumar, Vinod; Singh, Pooja; Bharadwaj, Chellapilla; Loake, Gary J.; Parida, Swarup K.; Masakapalli, Shyam Kumar; Gupta, Kapuganti Jagadis
    Seed germination is crucial for the plant life cycle. We investigated the role of nitric oxide (NO) in two chickpea varieties that differ in germination capacity: Kabuli, which has a low rate of germination and germinates slowly, and Desi, which shows improved germination properties. Desi produced more NO than Kabuli and had lower respiratory rates. As a result of the high respiration rates, Kabuli had higher levels of reactive oxygen species (ROS). Treatment with the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) reduced respiration in Kabuli and decreased ROS levels, resulting in accelerated germination rates. These findings suggest that NO plays a key role in the germination of Kabuli. SNAP increased the levels of transcripts encoding enzymes involved in carbohydrate metabolism and the cell cycle. Moreover, the levels of amino acids and organic acids were increased in Kabuli as a result of SNAP treatment. 1 H-nuclear magnetic resonance analysis revealed that Kabuli has a higher capacity for glucose oxidation than Desi. An observed SNAP-induced increase in 13C incorporation into soluble alanine may result from enhanced oxidation of exogenous [13C]glucose via glycolysis and the pentose phosphate pathway. A homozygous hybrid that originated from a recombinant inbred line population of a cross between Desi and Kabuli germinated faster and had increased NO levels and a reduced accumulation of ROS compared with Kabuli. Taken together, these findings demonstrate the importance of NO in chickpea germination via the control of respiration and ROS accumulation.