Browsing by Author "Subramanyam, Rajagopal"

Now showing 1 - 4 of 4

Metabolism and signalling in pea (Pisum sativum) leaves exposed to drought and subsequent recovery
(John Wiley & Sons, 2026) Pandey, Jayendra; Mantena, Chakradhar; Kumari, Aprajita; Singh, Pooja; Foyer, Christine H.; Gupta, Kapuganti Jagadis; Subramanyam, Rajagopal
Uncovering the metabolic and molecular mechanisms involved in plant responses to drought and subsequent recovery, is essential to identify drought tolerance mechanisms that can be used to improve crop plants. Here we combine plant physiology and biochemistry, with gene expression, quantitative proteomics and metabolite profiling to identify the genetic and metabolic networks that operate in plants experiencing and recovering from drought. Network analysis of transcripts, proteins and metabolites revealed that certain biological processes such as the tricarboxylic acid cycle and lipid metabolism had a strong impact on the overall control of leaf responses to drought and recovery. The stimulation of carbohydrate oxidation pathways is demonstrated to be a key node in the generation of energy and precursors required to support diverse survival pathways of defence.
Metabolomic response to high light from pgrl1 and pgr5 mutants of Chlamydomonas reinhardtii
(Springer Nature Publishing AG, 2023) Chouhan, Nisha; Marriboina, Sureshbabu; Kumari, Aprajita; Singh, Pooja; Yadav, Ranay Mohan; Gupta, Kapuganti Jagadis; Subramanyam, Rajagopal
Chlamydomonas (C.) reinhardtii metabolomic changes in cyclic electron flow-dependent mutants are still unknown. Here, we used mass spectrometric analysis to monitor the changes in metabolite levels in wild-type, cyclic electron-deficient mutants pgrl1 and pgr5 grown under high-light stress. A total of 55 metabolites were detected using GC-MS analysis. High-light stress-induced selective anaplerotic amino acids in pgr5. In addition, pgr5 showed enhancement in carbohydrate, polyamine, and polyol metabolism by 2.5-fold under high light. In response to high light, pgr5 triggers an increase in several metabolites involved in regulating osmotic pressure. Among these metabolites are glycerol pathway compounds such as glycerol-3-phosphate and glyceryl-glycoside, which increase significantly by 1.55 and 3.07 times, respectively. In addition, pgr5 also enhanced proline and putrescine levels by 2.6- and 1.36-fold under high light. On the other hand, pgrl1-induced metabolites, such as alanine and serine, are crucial for photorespiration when subjected to high-light stress. We also observed a significant increase in levels of polyols and glycerol by 1.37- and 2.97-fold in pgrl1 under high-light stress. Both correlation network studies and KEGG pathway enrichment analysis revealed that metabolites related to several biological pathways, such as amino acid, carbohydrate, TCA cycle, and fatty acid metabolism, were positively correlated in pgrl1 and pgr5 under high-light stress conditions. The relative mRNA expression levels of genes related to the TCA cycle, including PDC3, ACH1, OGD2, OGD3, IDH3, and MDH4, were significantly upregulated in pgrl1 and pgr5 under HL. In pgr5, the MDH1 level was significantly increased, while ACS1, ACS3, IDH2, and IDH3 levels were reduced considerably in pgrl1 under high-light stress. The current study demonstrates both pgr5 and prgl1 showed a differential defense response to high-light stress at the primary metabolites and mRNA expression level, which can be added to the existing knowledge to explore molecular regulatory responses of prg5 and pgrl1 to high-light stress.
Nitric oxide-mediated modulation of photorespiratory enzymes and photochemical components in leaves of pea plants (Pisum sativum)
(John Wiley & Sons, 2026) Saini, Deepak; Bharath, Pulimamidi; Gahir, Shashibhushan; Pandey, Jayendra; Vemula, Chandra Kaladhar; Gupta, Kapuganti Jagadis; Subramanyam, Rajagopal; Raghavendra, Agepati S
The photorespiratory metabolism safeguards photosynthesis against abiotic and biotic stress. Nitric oxide (NO) and reactive oxygen species (ROS) levels rise in plants during abiotic stress. Low concentrations of NO or ROS are beneficial as signalling molecules, but they can be toxic to plant cells at high concentrations. ROS are known to modulate photorespiration; however, it is unclear whether NO affects photorespiratory enzymes and photochemical components simultaneously. We therefore used sodium nitroprusside (SNP) under dark, moderate light (ML), or high light (HL) conditions to simultaneously investigate its impact on photorespiratory enzymes and photochemical components. The NO levels were increased upon SNP exposure in Pisum sativum leaves, particularly under HL conditions. The NO release in leaves was confirmed when the NO scavenger cPTIO (2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt) was present, since it decreased the majority of elevated NO. The nitrosative/oxidative stress in Pisum sativum leaves was confirmed by the increase in nitrosothiols and tyrosine-nitrated proteins, as well as reduced aconitase activity after SNP exposure at HL. The protein levels, mRNA levels, and the enzyme activities of the following four photorespiratory enzymes: glycolate oxidase (GO), hydroxypyruvate reductase (HPR), glycerate kinase (GK), and phosphoglycolate phosphatase (PGLP) were markedly increased under elevated NO conditions. Catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) also showed increased activity, elevated protein and transcript levels upon exposure to SNP. Parallel studies on chlorophyll a fluorescence confirmed that NO restricted electron transport at both PSII and PSI, inhibited photosynthesis and respiration, and damaged photosynthetic pigments. We concluded from this study that NO at high concentrations upregulated photorespiratory enzymes while inhibiting photochemical components such as photosystem II and I (PSII/PSI) simultaneously.
Overexpression of phytoglobin1 in rice leads to enhanced nitrogen use efficiency via modulation of nitric oxide
(John Wiley & Sons, 2025) Samant, Sanjib Bal; Swain, Jagannath; Yadav, Nidhi; Yadav, Reena; Singh, Pooja; Rai, Preeti; Sheri, Vijay; Sreeman, Sheshshayee; Subramanyam, Rajagopal; Pareek, Ashwani; Gupta, Kapuganti Jagadis
Nitric oxide (NO) is one of the byproducts of nitrogen metabolism. Excess amount of NO is scavenged by phytoglobins. The role of phytoglobin mediated NO homoeostasis in modulation of nitrate transporters was investigated using NO scavenger cPTIO, phytoglobin overexpressing rice and Arabidopsis. Growing plants under low nitrate leads to generation of reduced levels of NO accompanied by elevated expression of high affinity transporters (HATs) such as NRT2.1, NRT2.3 and NRT2.4. Scavenging of NO by cPTIO under optimal nitrate caused enhanced HATs expression. Phytoglobin overexpressing Arabidopsis showed improved growth and enhanced expression of HATs under low nitrogen in comparison to WT. Pretreatment of optimal nitrate grown plants with NO scavenger cPTIO enhanced HATs expression and shifting of these primed plants from optimal to low nitrate leads to further elevation of HATs expression accompanied by enhanced nitrogen uptake and its accumulation with positive effect on growth. Phytoglobin overexpression in rice leads to enhanced HATs expression, improved growth, nitrogen accumulation under low nitrate. Pgb OE lines showed enhanced accumulation of amino acids. Taken together our results suggest an important role of phytoglobins in nitrogen uptake and assimilation.