Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.3.1 (NADPH oxidase)
 11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fine-tuned and coordinated regulation of transport, metabolism and redox homeostasis allows plants to acclimate to osmotic and ionic stress caused by high salinity. Sugar beet is a highly salt tolerant crop plant and is therefore an interesting model to study sodium chloride (NaCl) acclimation in crops. Sugar beet plants were subjected to a final level of 300 mM NaCl for up to 14 d in hydroponics. Plants acclimated to NaCl stress by maintaining its growth rate and adjusting its cellular redox and reactive oxygen species (ROS) network. In order to understand the unusual suppression of ROS accumulation under severe salinity, the regulation of elements of the redox and ROS network was investigated at the transcript level. First, the gene families of superoxide dismutase (SOD), peroxiredoxins (Prx), alternative oxidase (AOX), plastid terminal oxidase (PTOX) and NADPH oxidase (RBOH) were identified in the sugar beet genome. Salinity induced the accumulation of Cu-Zn-SOD, Mn-SOD, Fe-SOD3, all AOX isoforms, 2-Cys-PrxB, PrxQ, and PrxIIF. In contrast, Fe-SOD1, 1-Cys-Prx, PrxIIB and PrxIIE levels decreased in response to salinity. Most importantly, RBOH transcripts of all isoforms decreased. This pattern offers a straightforward explanation for the low ROS levels under salinity. Promoters of stress responsive antioxidant genes were analyzed in silico for the enrichment of cis-elements, in order to gain insights into gene regulation. The results indicate that special cis-elements in the promoters of the antioxidant genes in sugar beet participate in adjusting the redox and ROS network and are fundamental to high salinity tolerance of sugar beet.
J Exp Bot 2017 02 01
PMID:Redox and Reactive Oxygen Species Network in Acclimation for Salinity Tolerance in Sugar Beet. 2833 62

Plant salt tolerance can be improved by grafting onto salt-tolerant rootstocks. However, the underlying signaling mechanisms behind this phenomenon remain largely unknown. To address this issue, we used a range of physiological and molecular techniques to study responses of self-grafted and pumpkin-grafted cucumber plants exposed to 75 mM NaCl stress. Pumpkin grafting significantly increased the salt tolerance of cucumber plants, as revealed by higher plant dry weight, chlorophyll content and photochemical efficiency (Fv/Fm), and lower leaf Na+ content. Salinity stress resulted in a sharp increase in H2O2 production, reaching a peak 3 h after salt treatment in the pumpkin-grafted cucumber. This enhancement was accompanied by elevated relative expression of respiratory burst oxidase homologue (RBOH) genes RbohD and RbohF and a higher NADPH oxidase activity. However, this increase was much delayed in the self-grafted plants, and the difference between the two grafting combinations disappeared after 24 h. The decreased leaf Na+ content of pumpkin-grafted plants was achieved by higher Na+ exclusion in roots, which was driven by the Na+/H+ antiporter energized by the plasma membrane H+-ATPase, as evidenced by the higher plasma membrane H+-ATPase activity and higher transcript levels for PMA and SOS1. In addition, early stomatal closure was also observed in the pumpkin-grafted cucumber plants, reducing water loss and maintaining the plant's hydration status. When pumpkin-grafted plants were pretreated with an NADPH oxidase inhibitor, diphenylene iodonium (DPI), the H2O2 level decreased significantly, to the level found in self-grafted plants, resulting in the loss of the salt tolerance. Inhibition of the NADPH oxidase-mediated H2O2 signaling in the root also abolished a rapid stomatal closure in the pumpkin-grafted plants. We concluded that the pumpkin-grafted cucumber plants increase their salt tolerance via a mechanism involving the root-sourced respiratory burst oxidase homologue-dependent H2O2 production, which enhances Na+ exclusion from the root and promotes an early stomatal closure.
J Exp Bot 2018 06 19
PMID:Root respiratory burst oxidase homologue-dependent H2O2 production confers salt tolerance on a grafted cucumber by controlling Na+ exclusion and stomatal closure. 2914 93

Root hair curling is an early and essential morphological change required for the success of the symbiotic interaction between legumes and rhizobia. At this stage rhizobia grow as an infection thread within root hairs and are internalized into the plant cells by endocytosis, where the PI3K enzyme plays important roles. Previous observations show that stress conditions affect early stages of the symbiotic interaction, from 2 to 30 min post-inoculation, which we term as very early host responses, and affect symbiosis establishment. Herein, we demonstrated the relevance of the very early host responses for the symbiotic interaction. PI3K and the NADPH oxidase complex are found to have key roles in the microsymbiont recognition response, modulating the apoplastic and intracellular/endosomal ROS induction in root hairs. Interestingly, compared with soybean mutant plants that do not perceive the symbiont, we demonstrated that the very early symbiont perception under sublethal saline stress conditions induced root hair death. Together, these results highlight not only the importance of the very early host-responses on later stages of the symbiont interaction, but also suggest that they act as a mechanism for local control of nodulation capacity, prior to the abortion of the infection thread, preventing the allocation of resources/energy for nodule formation under unfavorable environmental conditions.
J Exp Bot 2018 04 09
PMID:Phosphatidylinositol 3-kinase function at very early symbiont perception: a local nodulation control under stress conditions? 2939 94

Sugars play important roles in regulating plant growth, development, and stomatal movement. Here, we found that glucose triggered stomatal closure in a dose- and time-dependent manner in Arabidopsis. Pharmacological data showed that glucose-induced stomatal closure was greatly inhibited by catalase [CAT; a reactive oxygen species (ROS) scavenger], diphenyleneiodonium chloride (DPI; an NADPH oxidase inhibitor), lanthanum chloride (LaCl3; a Ca2+ channel blocker), EGTA (a Ca2+ chelator), and two nitrate reductase (NR) inhibitors, tungstate and sodium azide (NaN3), while it was not affected by salicylhydroxamic acid (SHAM; a peroxidase inhibitor). Moreover, glucose induced ROS and nitric oxide (NO) production in guard cells of Arabidopsis. The ROS production was almost completely removed by CAT, strongly restricted by DPI, and was not affected by SHAM. NO production was partially suppressed by tungstate and NaN3, and the levels of NO were significantly reduced in the nia1-1nia2-5 mutant. Additionally, glucose-triggered stomatal closure was significantly impaired in gin1-1, gin2-1, pyr1pyl1pyl2pyl4, abi1-1, ost1, slac1-4, cpk6-1, and nia1-1nia2-5 mutants. Likewise, the reductions in leaf stomatal conductance (gs) and transpiration rate (E) caused by glucose were reversed in the above mutants. These results suggest that glucose-triggered stomatal closure may be dependent on basal signaling through PYR/RCAR receptors and hexokinase1 (HXK1).
J Exp Bot 2018 03 24
PMID:Glucose triggers stomatal closure mediated by basal signaling through HXK1 and PYR/RCAR receptors in Arabidopsis. 2944 16

Potassium (K+) is a critical determinant of salinity tolerance, and H2O2 has been recognized as an important signaling molecule that mediates many physiological responses. However, the details of how H2O2 signaling regulates K+ uptake in the root under salt stress remain elusive. In this study, salt-sensitive cucumber and salt-tolerant pumpkin which belong to the same family, Cucurbitaceae, were used to answer the above question. We show that higher salt tolerance in pumpkin was related to its superior ability for K+ uptake and higher H2O2 accumulation in the root apex. Transcriptome analysis showed that salinity induced 5816 (3005 up- and 2811 down-) and 4679 (3965 up- and 714 down-) differentially expressed genes (DEGs) in cucumber and pumpkin, respectively. DEGs encoding NADPH oxidase (respiratory burst oxidase homolog D; RBOHD), 14-3-3 protein (GRF12), plasma membrane H+-ATPase (AHA1), and potassium transporter (HAK5) showed higher expression in pumpkin than in cucumber under salinity stress. Treatment with the NADPH oxidase inhibitor diphenylene iodonium resulted in lower RBOHD, GRF12, AHA1, and HAK5 expression, reduced plasma membrane H+-ATPase activity, and lower K+ uptake, leading to a loss of the salinity tolerance trait in pumpkin. The opposite results were obtained when the plants were pre-treated with exogenous H2O2. Knocking out of RBOHD in pumpkin by CRISPR/Cas9 [clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9] editing of coding sequences resulted in lower root apex H2O2 and K+ content and GRF12, AHA1, and HAK5 expression, ultimately resulting in a salt-sensitive phenotype. However, ectopic expression of pumpkin RBOHD in Arabidopsis led to the opposite effect. Taken together, this study shows that RBOHD-dependent H2O2 signaling in the root apex is important for pumpkin salt tolerance and suggests a novel mechanism that confers this trait, namely RBOHD-mediated transcriptional and post-translational activation of plasma membrane H+-ATPase operating upstream of HAK5 K+ uptake transporters.
J Exp Bot 2019 10 24
PMID:Tissue-specific respiratory burst oxidase homolog-dependent H2O2 signaling to the plasma membrane H+-ATPase confers potassium uptake and salinity tolerance in Cucurbitaceae. 3129 Sep 78

Primary physicochemical steps in microwounding of plants were investigated using electrochemical nano- and microprobes, with a focus on the role of oxygen in the wounding responses of individual plant cells. Electrochemical measurements of cell oxygen content were made with carbon-filled quartz micropipettes with platinum-coated tips (oxygen nanosensors). These novel platinum nanoelectrodes are useful for understanding cell oxygen metabolism and can be employed to study the redox biochemistry and biology of cells, tissues and organisms. We show here that microinjury of Chara corallina internodal cells with the tip of a glass micropipette is associated with a drastic decrease in oxygen concentration at the vicinity of the stimulation site. This decrease is reversible and lasts for up to 40 minutes. Membrane stretching, calcium influx, and cytoskeleton rearrangements were found to be essential for the localized oxygen depletion induced by cell wall microwounding. Inhibition of electron transport in chloroplasts or mitochondria did not affect the magnitude or timing of the observed response. In contrast, the inhibition of NADPH oxidase activity caused a significant reduction in the amplitude of the decrease in oxygen concentration. We suggest that the observed creation of localized anoxic conditions in response to cell wall puncture might be mediated by NADPH oxidase.
J Exp Bot 2020 01 01
PMID:Prolonged oxygen depletion in microwounded cells of Chara corallina detected with novel oxygen nanosensors. 3156 50

Nitric oxide (NO) and hydrogen sulfide (H2S) are two key molecules in plant cells which participate, directly or indirectly, as regulators of protein functions through derived posttranslational modifications (PTMs) mainly tyrosine nitration, S-nitrosation and persulfidation. These PTMs allow the participation of both NO and H2S signal molecules in a wide range of cellular processes either physiological or under stressful circumstances. NADPH partakes in the cellular redox status and it is a key cofactor necessary for cell growth and development because it participates in significant biochemical routes such as fatty acid, carotenoid and proline biosynthesis, shikimate pathway as well as in cellular detoxification processes including the ascorbate-glutathione cycle, the NADPH-dependent thioredoxin reductase (NTR) or the superoxide-generating NADPH oxidase. Plant cells have diverse mechanism to generate NADPH by a group of NADP-dependent oxidoreductases including the ferredoxin-NADP reductase (FNR), NADP-glyceraldehyde-3-phosphate dehydrogenase (NADP-GAPDH), NADP-dependent malic enzyme (NADP-ME), NADP-dependent isocitrate dehydrogenase (NADP-ICDH), and both enzymes of the oxidative pentose phosphate pathway (OxPPP), designated as glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH). These enzymes consist of different isozymes located in diverse subcellular compartments (chloroplasts, cytosol, mitochondria and peroxisomes) which contribute to the NAPDH cellular pool. The present review provides a comprehensive overview about how PTMs promoted by NO (Tyr-nitration and S-nitrosation), H2S (persulfidation) and glutathione (glutathionylation), affect the cellular redox status through the regulation of the NADP-dependent dehydrogenases.
J Exp Bot 2020 Sep 18
PMID:Nitric oxide (NO) and hydrogen sulfide (H2S) modulate the NADPH-generating enzymatic system in higher plants. 3294 78


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