共查询到20条相似文献,搜索用时 15 毫秒
3.
Precocious leaf senescence can reduce crop yield and quality by limiting the growth stage. Melatonin has been shown to delay leaf senescence; however, the underlying mechanism remains obscure. Here, we show that melatonin offsets abscisic acid (ABA) to protect photosystem II and delay the senescence of attached old leaves under the light. Melatonin induced H 2O 2 accumulation accompanied by an upregulation of melon respiratory burst oxidase homolog D ( CmRBOHD) under ABA-induced stress. Both melatonin and H 2O 2 induced the accumulation of cytoplasmic-free Ca 2+ ([Ca 2+] cyt) in response to ABA, while blocking of Ca 2+ influx channels attenuated melatonin- and H 2O 2-induced ABA tolerance. CmRBOHD overexpression induced [Ca 2+] cyt accumulation and delayed leaf senescence, whereas deletion of Arabidopsis AtRBOHD, a homologous gene of CmRBOHD, compromised the melatonin-induced [Ca 2+] cyt accumulation and delay of leaf senescence in Arabidopsis under ABA stress. Furthermore, melatonin, H 2O 2 and Ca 2+ attenuated ABA-induced K + efflux and subsequent cell death. CmRBOHD overexpression and AtRBOHD deletion alleviated and aggravated the ABA-induced K + efflux, respectively. Taken together, our study unveils a new mechanism by which melatonin offsets ABA action to delay leaf senescence via RBOHD-dependent H 2O 2 production that triggers [Ca 2+] cyt accumulation and subsequently inhibits K + efflux and delays cell death/leaf senescence in response to ABA. 相似文献
5.
MicroRNA393 (miR393) has been shown to regulate plant water stress tolerance through an auxin signaling pathway. However, its role in soybean (Glycine max [L.] Merr.) has not yet been reported. Here, we examined the expression pattern of miR393 family members and their target gene GmTIR1 in water-stressed roots. Subsequently, we analyzed the functions of miR393 in the regulation of water stress tolerance and its relationship with GmTIR1 and abscisic acid (ABA) using a transgenic hairy root assay. Under water stress, miR393 family genes exhibited diverse expression patterns. Overexpression and knockdown analysis demonstrated that miR393a reduced water stress tolerance as measured by root vigor, net photosynthetic rate (Pn), and relative water content (RWC). Moreover, miR393a also caused down-regulation of GmTIR1A and GmTIR1B expression, an early decrease in hydrogen peroxide (H2O2) levels, early and late declines in ABA content and antioxidant activities, and a late elevation of H2O2 and malondialdehyde (MDA) concentrations in stressed hairy roots. However, overexpression and RNAi analyses showed that GmTIR1A and GmTIR1B triggered an early increase in H2O2, a rise in antioxidant activities during the early and late stages, a late decline in H2O2 and MDA contents, and a rise in root vigor, Pn, and RWC under water stress. Similarly, exogenously supplied ABA caused early H2O2 accumulation, early and late increases in antioxidant capacity, and a late decrease in oxidative damage in stressed miR393a-overexpressing roots. Therefore, our study presents a valuable model in which miR393a prevents early GmTIR1- and ABA-dependent increases in H2O2 and thus triggers a rise in antioxidant capacity, root vigor, RWC, and Pn, consequently decreasing water stress tolerance. 相似文献
6.
Here we examined whether Ca 2+/Calmodulin (CaM) is involved in abscisic acid (ABA)-induced antioxidant defense and the possible relationship between CaM
and H 2O 2 in ABA signaling in leaves of maize ( Zea mays L.) plants exposed to water stress. An ABA-deficient mutant vp5 and its wild type were used for the experimentation. We found that water stress enhanced significantly the contents of CaM
and H 2O 2, and the activities of chloroplastic and cytosolic superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione
reductase (GR), and the gene expressions of the CaM1, cAPX, GR1 and SOD4 in leaves of wild-type maize. However, the increases mentioned above were almost arrested in vp5 plants and in the wild-type plants pretreated with ABA biosynthesis inhibitor tungstate (T), suggesting that ABA is required
for water stress-induced H 2O 2 production, the enhancement of CaM content and antioxidant defense. Besides, we showed that the up-regulation of water stress-induced
antioxidant defense was almost completely blocked by pretreatment with Ca 2+ inhibitors, CaM antagonists and reactive oxygen (ROS) manipulators. Moreover, the analysis of time course of CaM and H 2O 2 production under water stress showed that the increase in CaM content preceded that of H 2O 2. These results suggested that Ca 2+/CaM and H 2O 2 were involved in the ABA-induced antioxidant defense under water stress, and the increases of Ca 2+/CaM contents triggered H 2O 2 production, which inversely affected the contents of CaM. Thus, a cross-talk between Ca 2+/CaM and H 2O 2 may play a pivotal role in the ABA signaling. 相似文献
7.
We have monitored the changes in antioxidant enzyme activities and H 2O 2 concentrations in roots of rice ( Oryza sativa L., cv. Taichung Native 1) seedlings treated with exogenous abscisic acid(ABA). Decrease in superoxide dismutase (SOD) and catalase (CAT) activities was observed in rice roots in the presence of ABA. However, ascorbate peroxide (APX) and glutathione reductase (GR) activities were increased after the ABA treatment. ABA treatment resulted in an increase in H 2O 2 concentrations in rice roots. Pre-treatment with dimethylthiourea, a chemical trap for H 2O 2, and diphenyleneiodonium chloride (DPI), a well known inhibitor of NADPH oxidase, inhibited ABA-induced accumulation of H 2O 2 and ABA-induced activities of APX and GR. ABA-induced accumulation of H 2O 2 was found to be prior to ABA-induced activities of APX and GR. Our results suggest that H 2O 2 is involved in ABA-induced APX and GR activities in rice roots. 相似文献
8.
Abscisic acid (ABA) regulates plant adaptive responses to various environmental stresses. 9- cis-epoxycarotenoid dioxygenase (NCED) is the key enzyme of ABA biosynthesis in higher plants. A NCED gene, SgNCED1, was overexpressed in transgenic tobacco plants which resulted in 51–77% more accumulation of ABA in leaves. Transgenic tobacco
plants decreased stomatal conductance, transpiration rate, and photosynthetic rate but induced activities of superoxide dismutase
(SOD), catalase (CAT), and ascorbate-peroxidase (APX). Hydrogen peroxide (H 2O 2) and nitric oxide (NO) in leaves were also induced in the transgenic plants. Compared to the wild-type control, the transgenic
plants improved growth under 0.1 M mannitol-induced drought stress and 0.1 M NaCl-induced salinity stress. It is suggested
that the ABA-induced H 2O 2 and NO generation upregulates the stomatal closure and antioxidant enzymes, and therefore increases drought and salinity
tolerance in the transgenic plants. 相似文献
9.
Peanut plants exposed to water stress induced by polyethylene glycol (PEG) accumulated abscisic acid (ABA) and hydrogen peroxide (H 2O 2), the increase being significant at 12 and 24 h after addition, respectively. To address the question whether the increase in H 2O 2 production was related to ABA accumulation, the peanut leaves were pretreated with ABA biosynthesis inhibitor (sodium tungstate) and then exposed to water stress. Under these conditions, a decrease of ABA and H 2O 2 content were found after 12 h. The addition of 100 μM ABA restored H 2O 2 content reaching values similar to those under water stress at 12 h. We concluded that ABA accumulation is the first signal that triggers the H 2O 2 generation in peanut during first 12 h but its subsequent production is partially ABA-independent. 相似文献
11.
In this study, the role of the rice(Oryza sativa L.)histidine kinase Os HK3 in abscisic acid(ABA)-induced antioxidant defense was investigated. Treatments with ABA, H2O2,and polyethylene glycol(PEG) induced the expression of Os HK3 in rice leaves, and H2O2 is required for ABA-induced increase in the expression of Os HK3 under water stress. Subcellular localization analysis showed that Os HK3 is located in the cytoplasm and the plasma membrane. The transient expression analysis and the transient RNA interference test in rice protoplasts showed that Os HK3 is required for ABA-induced upregulation in the expression of antioxidant enzymes genes and the activities of antioxidant enzymes. Further analysis showed that Os HK3 functions upstream of the calcium/calmodulin-dependent protein kinase Os DMI3 and the mitogen-activated protein kinase Os MPK1 to regulate the activities of antioxidant enzymes in ABA signaling. Moreover, Os HK3was also shown to regulate the expression of nicotinamide adenine dinucleotide phosphate oxidase genes, Osrboh B and Osrboh E, and the production of H2O2 in ABA signaling. Our data indicate that Os HK3 play an important role in the regulation of ABA-induced antioxidant defense and in the feedback regulation of H2O2 production in ABA signaling. 相似文献
12.
Drought, a primary abiotic stress, seriously affects plant growth and productivity. Stomata play a vital role in regulating gas exchange and drought adaptation. However, limited knowledge exists of the molecular mechanisms underlying stomatal movement in trees. Here, PeCHYR1, a ubiquitin E3 ligase, was isolated from Populus euphratica, a model of stress adaptation in forest trees. PeCHYR1 was preferentially expressed in young leaves and was significantly induced by ABA (abscisic acid) and dehydration treatments. To study the potential biological functions of PeCHYR1, transgenic poplar 84K ( Populus alba × Populus glandulosa) plants overexpressing PeCHYR1 were generated. PeCHYR1 overexpression significantly enhanced H 2O 2 production and reduced stomatal aperture. Transgenic lines exhibited increased sensitivity to exogenous ABA and greater drought tolerance than that of WT (wild‐type) controls. Moreover, up‐regulation of PeCHYR1 promoted stomatal closure and decreased transpiration, resulting in strongly elevated WUE (water use efficiency). When exposed to drought stress, transgenic poplar maintained higher photosynthetic activity and biomass accumulation. Taken together, these results suggest that PeCHYR1 plays a crucial role in enhancing drought tolerance via ABA‐induced stomatal closure caused by hydrogen peroxide (H 2O 2) production in transgenic poplar plants. 相似文献
13.
Hydrogen peroxide (H 2O 2) functions as a signal molecule in plants under abiotic and biotic stresses. Leaves of detached maize ( Zea mays L.) seedlings were used to study the function of H 2O 2 pretreatment in osmotic stress resistance. Low H 2O 2 concentration (10 mM) which did not cause a visual symptom of water deficit (leaf rolling) was applied to the seedlings. Exogenous H 2O 2 alone increased leaf water potential, endogenous H 2O 2 content, abscisic acid (ABA) concentration, and metabolite levels including soluble sugars, proline, and polyamines while it decreased lipid peroxidation and stomatal conductance. Osmotic stress induced by polyethylene glycol (PEG 6000) decreased leaf water potential and stomatal conductance but enhanced lipid peroxidation, endogenous H 2O 2 content, the metabolite levels, and ABA content. H 2O 2 pretreatment also induced the metabolite accumulation and improved water status, stomatal conductance, lipid peroxidation, ABA, and H 2O 2 levels under osmotic stress. These results indicated that H 2O 2 pretreatment may alleviate water loss and induce osmotic stress resistance by increasing the levels of soluble sugars, proline, and polyamines thus ABA and H 2O 2 production slightly decrease in maize seedlings under osmotic stress. 相似文献
16.
Multiple cellular events like dynamic actin reorganization and hydrogen peroxide (H 2O 2) production were demonstrated to be involved in abscisic acid (ABA)‐induced stomatal closure. However, the relationship between them as well as the underlying mechanisms remains poorly understood. Here, we showed that H 2O 2 generation is indispensable for ABA induction of actin reorganization in guard cells of Arabidopsis that requires the presence of ARP2/3 complex. H 2O 2‐induced stomatal closure was delayed in the mutants of arpc4 and arpc5, and the rate of actin reorganization was slowed down in arpc4 and arpc5 in response to H 2O 2, suggesting that ARP2/3‐mediated actin nucleation is required for H 2O 2‐induced actin cytoskeleton remodelling. Furthermore, the expression of H 2O 2 biosynthetic related gene AtrbohD and the accumulation of H 2O 2 was delayed in response to ABA in arpc4 and arpc5, demonstrating that misregulated actin dynamics affects H 2O 2 production upon ABA treatment. These results support a possible causal relation between the production of H 2O 2 and actin dynamics in ABA‐mediated guard cell signalling: ABA triggers H 2O 2 generation that causes the reorganization of the actin cytoskeleton partially mediated by ARP2/3 complex, and ARP2/3 complex‐mediated actin dynamics may feedback regulate H 2O 2 production. 相似文献
17.
Magnesium (Mg) deficiency in plants is a widespread problem, affecting productivity and quality in agriculture. The mechanism
of Mg deficiency inducing antioxidant enzyme activities has not been elucidated in rice. We examined the relationship among
abscisic acid (ABA), H 2O 2, and antioxidant enzymes in the leaves of rice seedlings grown under conditions of Mg deficiency. The expression of OsRab16A, an ABA responsive gene, was used to determine the content of ABA. Mg deficiency resulted in increased ABA content in leaves
of rice seedlings. The production of H 2O 2 was examined by 3,3-diaminobenzidine staining and a colorimetric method. Mg deficiency also induced H 2O 2 production in leaves, which was blocked by dipehnyleneiodonium chloride (DPI), an NADPH oxidase inhibitor. Tungstate (Tu),
an ABA biosynthesis inhibitor, was effective in reducing Mg deficiency-increased ABA content, as well as Mg deficiency-induced
H 2O 2 production. Both Tu and DPI were effective in reducing Mg deficiency-induced activities of superoxide dismutase, ascorbate
peroxidase, glutathione reductase, and catalase in the leaves. Mg deficiency-induced ABA accumulation may trigger increased
production of H 2O 2, which may involve plasma-membrane NADPH oxidase, and, in turn, up-regulates the activities of antioxidant enzymes in leaves
of rice seedlings. 相似文献
19.
The physiological role of peroxisomal ascorbate peroxidases (pAPX) is unknown; therefore, we utilized pAPX4 knockdown rice and catalase (CAT) inhibition to assess its role in CAT compensation under high photorespiration. pAPX4 knockdown induced co‐suppression in the expression of pAPX3. The rice mutants exhibited metabolic changes such as lower CAT and glycolate oxidase (GO) activities and reduced glyoxylate content; however, APX activity was not altered. CAT inhibition triggered different changes in the expression of CAT, APX and glutathione peroxidase (GPX) isoforms between non‐transformed (NT) and silenced plants. These responses were associated with alterations in APX, GPX and GO activities, suggesting redox homeostasis differences. The glutathione oxidation‐reduction states were modulated differently in mutants, and the ascorbate redox state was greatly affected in both genotypes. The pAPX suffered less oxidative stress and photosystem II (PSII) damage and displayed higher photosynthesis than the NT plants. The improved acclimation exhibited by the pAPX plants was indicated by lower H 2O 2 accumulation, which was associated with lower GO activity and glyoxylate content. The suppression of both pAPXs and/or its downstream metabolic and molecular effects may trigger favourable antioxidant and compensatory mechanisms to cope with CAT deficiency. This physiological acclimation may involve signalling by peroxisomal H 2O 2, which minimized the photorespiration. 相似文献
20.
Diurnal patterns of gas exchange and chlorophyll (Chl) fluorescence parameters of photosystem 2 (PS2) as well as H 2O 2 content were analyzed in Reaumuria soongorica (Pall.) Maxim., a perennial semi-shrub. The rate of photorespiration was estimated by combined measurement of gas exchange
and Chl fluorescence. The rate of photorespiration increased with the increasing drought stress (DS). The ratio of carboxylation
electron flow to oxygenation electron flow (J c/J o) and the maximal photochemical efficiency of PS2 (variable to maximum fluorescence ratio, F v/F m) decreased with the increasing DS. F v/F m in isonicotinic acid hydrazide (INH)-sprayed plants was lower than that in normal plants under moderate DS, but no significant
difference was observed under severe DS. H 2O 2 content in INH-sprayed plants was significantly lower than that in normal plants under severe DS. Taken together, photorespiration
in R. soongorica consumed excess electrons and protected photosynthetic apparatus under moderate DS, whereas it accelerated H 2O 2 accumulation markedly and induced the leaf abscission under severe DS. 相似文献
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