Institutional Publications
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Item The emerging roles of nitric oxide and its associated scavengers-phytoglobins-in plant symbiotic interactions(Oxford University Press, 2024) Pathak, Pradeep Kumar; Yadav, Nidhi; Kaladhar, Vemula Chandra; Jaiswal, Rekha; Kumari, Aprajita; Igamberdiev, Abir U.; Loake, Gary J.; Gupta, Kapuganti JagadisA key feature in the establishment of symbiosis between plants and microbes is the maintenance of the balance between the production of the small redox-related molecule, nitric oxide (NO), and its cognate scavenging pathways. During the establishment of symbiosis, a transition from a normoxic to a microoxic environment often takes place, triggering the production of NO from nitrite via a reductive production pathway. Plant hemoglobins [phytoglobins (Phytogbs)] are a central tenant of NO scavenging, with NO homeostasis maintained via the Phytogb–NO cycle. While the first plant hemoglobin (leghemoglobin), associated with the symbiotic relationship between leguminous plants and bacterial Rhizobium species, was discovered in 1939, most other plant hemoglobins, identified only in the 1990s, were considered as non-symbiotic. From recent studies, it is becoming evident that the role of Phytogbs1 in the establishment and maintenance of plant–bacterial and plant–fungal symbiosis is also essential in roots. Consequently, the division of plant hemoglobins into symbiotic and non-symbiotic groups becomes less justified. While the main function of Phytogbs1 is related to the regulation of NO levels, participation of these proteins in the establishment of symbiotic relationships between plants and microorganisms represents another important dimension among the other processes in which these key redox-regulatory proteins play a central role.Item Nitric oxide regulates mitochondrial biogenesis in plants(John Wiley & Sons, 2023) Kumari, Aprajita; Kaladhar, Vemula Chandra; Yadav, Nidhi; Singh, Pooja; Reddy, Kishorekumar; Gupta, Kapuganti JagadisThe 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.
