Single cell C
4
(SCC
4
) plants, discovered around two decades ago, are promising materials for efforts for genetic engineering of C
4
photosynthesis into C
3
crops. Unlike C
4
plants with Kranz ...anatomy, they exhibit a fully functional C
4
photosynthesis in just a single cell and do not require mesophyll and bundle sheath cell spatial separation.
Bienertia sinuspersici
is one such SCC
4
plant, with NAD-malic enzyme (NAD-ME) subtype C
4
photosynthesis. Its chlorenchyma cell consist of two compartments, peripheral compartment (PC), analogous to mesophyll cell, and central compartment (CC), analogous to bundle sheath cell. Since oxidative stress creates an important constraint for plants under salinity and drought, we comparatively examined the response of enzymatic antioxidant system, H
2
O
2
and TBARS contents, peroxiredoxin Q, NADPH thioredoxin reductase C, and plastid terminal oxidase protein levels of PC chloroplasts (PCC) and CC chloroplasts (CCC). Except for protein levels, these parameters were also examined on the whole leaf level, as well as catalase and NADPH oxidase activities, water status and growth parameters, and levels of C
4
photosynthesis related transcripts. Many C
4
photosynthesis related transcript levels were elevated, especially under drought. Activities of dehydroascorbate reductase and especially peroxidase were elevated under drought in both compartments (CCC and PCC). Even though decreases of antioxidant enzyme activities were more prevalent in PCC, and the examined redox regulating protein levels, especially of peroxiredoxin Q, were elevated in CCC under both stresses, PCC was less damaged by either stress. These suggest PCC is more tolerant and has other means of preventing or alleviating oxidative damage.
The aim of this work was to investigate changes in isoenzyme patterns of enzymes related to reactive oxygen species (ROS) detoxification such as superoxide dismutase (SOD), catalase (CAT), peroxidase ...(POX), ascorbate peroxidase (APX), glutathione reductase (GR), and glutathione-S-transferase (GST) in cotton under Mg deficiency. Moreover, we aimed to elucidate how a ROS producer, NADPH oxidase (NOX), responds to changing Mg levels. Cotton plants were grown with different concentrations of MgSO 4 in hydroponic medium to create nutrient deficiency (0, 75, 150, 1000 µM Mg). Gradual decreases in growth and photosynthetic rates were observed with declining Mg concentrations and 0, 75, and 150 µM Mg increased oxidative stress as evidenced by H O and 2 2 lipid peroxidation. Total activities of SOD, CAT, POX, APX, GR, and GST were increased while NOX activity was decreased with Mg deficiency. The activities of GR and GST were highest in plants treated with 0 µM Mg, indicating excess use of glutathione for redox regulation. The most striking results were the changes in isoenzyme patterns of SOD, NOX, POX, and GST. For example, a new Cu/ ZnSOD isoenzyme was induced in plants treated with 0 µM Mg. Cotton plants adapt to Mg deficiency by changing the intensity of existing isoenzymes or inducing new ones.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
•Excess ROS levels cause increased production of lipid peroxidation derived RCS.•RCS have detrimental effects due to their ability to modify biological molecules.•Recently, it has been shown that RCS ...also act as signaling molecules just like ROS.•This review discusses interaction among antioxidant system, ROS and RCS metabolism.
It is well known that environmental stress conditions enhance the production of reactive oxygen species (ROS), which have dual roles with damaging effects to biomolecules and with signaling roles. When enzymatic or non-enzymatic antioxidant defense of the cell is overwhelmed with excess production of ROS, it results in disruption of lipids via oxidation, which causes production of highly reactive lipid peroxidation-derived molecules such as 4-hydroxy-2-nonenal, 4-hydroxy-2-hexenal, malondialdehyde and acrolein. These unstable molecules are named as reactive carbonyl species (RCS) and high concentrations of RCS can cause irreversible damage in plant cells, which ultimately leads to cell death. Although there is a vast amount of studies on the nature of RCS in animals, studies in plants are limited, which mostly investigate their detoxification mechanisms and their damaging effects. Recently, just like ROS, signal roles are being postulated for RCS. In this review, the ROS and RCS production mechanisms and sites in plant cells are introduced and the RCS detoxification mechanisms including aldehyde dehydrogenases, aldo/keto reductases, 2-alkenal reductases and glutathione transferases are described. Moreover, besides their damaging effects, evidence related to signal roles of RCS are discussed. Also, the interaction between ROS and RCS metabolism is evaluated via RCS – antioxidant defense interaction.
•Role of RCS (HNE, HEE, ACR) on induction of antioxidant defence was investigated.•Low levels of RCS (0.1 μM) were more efficient in induction of antioxidant enzymes.•H2O2 scavenging enzymes were ...more responsive to RCS treatments.•High levels of RCS downregulated RBOH gene expression in A. thaliana, but not in E. parvulum.•RCS treatments induced expressions of Na+/H+ antiporters (SOS1, NHX1 and NHX5).
Breakdown of lipids in cell membranes by reactive oxygen species (ROS) causes production of lipid peroxidation products such as 4-hydroxy-2-nonenal (HNE), 4-hydroxy-2-hexenal (HHE), and acrolein (ACR) which are highly electrophilic due to their α-β-unsaturated carbonyl structures and named as reactive carbonyl species (RCS). The aim of this work was to investigate if RCS can induce antioxidant defence in plants and if there is a differential response in glycophytes and halophytes under non-stress conditions. For this aim, different amount and types of RCS (0.1 μM, 1 μM, 10 μM HNE, HHE and ACR) were exogenously applied to both Arabidopsis thaliana and Eutrema parvulum, and activities of some antioxidant enzymes (SOD, CAT, POX, APX) and their isoenzymes of SOD and CAT were determined. Also, to reveal role of RCS on ROS signal transduction, NADPH oxidase (NOX) activity and expression levels of abiotic stress related RBOH genes (RBOHD, RBOHF) were measured. To further elucidate the role of RCS on regulation of ion transporters in glycophyte and halophyte plants, expressions of Na+/H+ ion exchange channels on tonoplast (Na+/H+ exchanger NHX1, NHX5) and plasma membrane (salt overly sensitive 1, SOS1) were investigated. Overall, data provided in this manuscript provided evidence for regulation of antioxidant defence enzymes and ROS signalling in plants depending on the type and concentration of the RCS. In regards of glycophyte and halophyte comparison, remarkable differences were, (i) response of A. thaliana H2O2 scavenging enzymes (CAT, POX, APX) was stronger to RCS treatment when compared to E. parvulum, (ii) NADPH oxidase mediated ROS signalling was downregulated in A. thaliana, while it was maintained in E. parvulum in response to RCS. In addition, gene expression data demonstrated that RCS treatments can induced SOS1, NHX1 and NHX5 expression depending, again, on type and concentration of RCS in the absence of salt stress. Moreover, growth data indicate that RCS treatments can mitigate negative effects of salt stress in E. parvulum, but not in A. thaliana.
C4 plants are acclimated to drought and high temperatures that are detrimental for C3 plants, and they are well equipped with a better antioxidant capacity to cope with oxidative stress caused by ...abiotic stresses. However, how C3 and C4 plants respond to oxidative stress that occurs in a specific compartment of the cell, such as chloroplast or mitochondria, is still not known. Therefore, understanding antioxidant responses of different carboxylation pathways to reactive oxygen species (ROS) at organelle level deserves an investigation. In the present study, the production of organelle originated ROS was induced with chemical agents specific to mitochondria (rotenone =ROT) and chloroplasts (methyl viologen = MV and DCMU), and antioxidant response of Flaveria robusta (C3) and F. bidentis (C4) were studied. For this purpose, activities of antioxidant system (superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductases (GR)), and isoenzymes of SOD, CAT, and NADPH oxidase (NOX) activity were determined. Treatment of leaves with ROT, MV and DCMU for 4 h induced lipid peroxidation by 38%, 18% and 41% respectively in F. robusta, while 81%, 75% and 56% induction were observed for same inhibitors in F. bidentis. On the other hand, treatment with inhibitors cause decrease of CAT activity in F. robusta (27% with ROT), while increased CAT activity was observed in F. bidentis (maximum 68% with MV). Overall, the antioxidant defense responses of C3 and C4 plants were distinctive to organelle induced oxidative stress, especially in chloroplast-sourced accumulation of ROS.
•Response to organellar oxidative stress was studied in C3 and C4 species of Flaveria.•Methyl viologen, rotenone and DCMU was used to induce organellar oxidative stress.•Flaveria bidentis (C4) was more sensitive after 4 h treatment as evident by lipid peroxidation.•F. robusta (C3) CAT activity decreased, while it was increased in Flaveria bidentis (C4).•Antioxidant responses of C3 and C4 species were distinctive to organellar oxidative stress.
Single cell C
(SCC
) plants, discovered around two decades ago, are promising materials for efforts for genetic engineering of C
photosynthesis into C
crops. Unlike C
plants with Kranz anatomy, they ...exhibit a fully functional C
photosynthesis in just a single cell and do not require mesophyll and bundle sheath cell spatial separation.
is one such SCC
plant, with NAD-malic enzyme (NAD-ME) subtype C
photosynthesis. Its chlorenchyma cell consist of two compartments, peripheral compartment (PC), analogous to mesophyll cell, and central compartment (CC), analogous to bundle sheath cell. Since oxidative stress creates an important constraint for plants under salinity and drought, we comparatively examined the response of enzymatic antioxidant system, H
O
and TBARS contents, peroxiredoxin Q, NADPH thioredoxin reductase C, and plastid terminal oxidase protein levels of PC chloroplasts (PCC) and CC chloroplasts (CCC). Except for protein levels, these parameters were also examined on the whole leaf level, as well as catalase and NADPH oxidase activities, water status and growth parameters, and levels of C
photosynthesis related transcripts. Many C
photosynthesis related transcript levels were elevated, especially under drought. Activities of dehydroascorbate reductase and especially peroxidase were elevated under drought in both compartments (CCC and PCC). Even though decreases of antioxidant enzyme activities were more prevalent in PCC, and the examined redox regulating protein levels, especially of peroxiredoxin Q, were elevated in CCC under both stresses, PCC was less damaged by either stress. These suggest PCC is more tolerant and has other means of preventing or alleviating oxidative damage.
Drought is a prevalent natural factor limiting crop production in arid regions across the world. To overcome this limitation, seeds are sown much deeper to boost germination by soil moisture produced ...by underground water. Seed pretreatment can effectively induce deep-sowing tolerance in plants. In the present study, we evaluated whether H2O2 pretreatment of seeds can initiate metabolic changes and lead to improved deep-sowing tolerance in wheat. Pretreatment with 0.05 μM H2O2 promoted first internode elongation by 13% in the deep-sowing tolerant wheat cultivar “Tir” and by 32% in the sensitive cultivar “Kıraç-66” under deep-sowing conditions, whereas internode elongation was inhibited by diphenyleneiodonium chloride. In contrast to Tir seedlings, H2O2 levels in the first internode of Kıraç-66 seedlings increased under deep-sowing condition in the H2O2-treated group compared to controls. Moreover, these seedlings had significantly lower catalase (CAT), peroxidase (POX), and ascorbate peroxidase (APX) activities but higher NADPH oxidase (NOX) and superoxide dismutase (SOD) activities under the same conditions, which consequently induced greater H2O2 accumulation. Contrary to Tir, both total glutathione and glutathione S-transferase (GST) activity decreased in Kıraç-66 after deep-sowing at 10 cm. However, H2O2 treatment increased the total glutathione amounts and the activities of glutathione-related enzymes (except GST and GPX) in the first internode of Kıraç-66. Taken together, these data support that H2O2 acts as a signaling molecule in the activation of antioxidant enzymes (specifically NOX, SOD, and CAT), regulation of both glutathione-related enzymes and total glutathione content, and upregulation of the cell wall-loosening protein gene TaEXPB23.
•Pretreatment of seeds with H2O2 improved deep-sowing tolerance of wheat seedlings.•H2O2 promoted first internode elongation of seedlings at the 10 cm depth.•Under deep-sowing conditions, H2O2 altered antioxidant enzyme activities.•Under deep-sowing conditions, H2O2 maintained glutathione homeostasis.•H2O2 induces the upregulation of the cell wall-related gene TaEXPB23.
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