Cytokinin- and auxin-induced stomatal opening involves a decrease in levels of hydrogen peroxide in guard cells of Vicia faba

2006 ◽  
Vol 33 (6) ◽  
pp. 573 ◽  
Author(s):  
Xi-Gui Song ◽  
Xiao-Ping She ◽  
Jun-Min He ◽  
Chen Huang ◽  
Tu-sheng Song

Previous studies have shown that cytokinins and auxins can induce the opening of stomata. However, the mechanism of stomatal opening caused by cytokinins and auxins remains unclear. The purpose of this paper is to investigate the relationship between hydrogen peroxide (H2O2) levels in guard cells and stomatal opening induced by cytokinins and auxins in Vicia faba. By means of stomatal bioassay and laser-scanning confocal microscopy, we provide evidence that cytokinins and auxins reduced the levels of H2O2 in guard cells and induced stomatal opening in darkness. Additionally, cytokinins not only reduced exogenous H2O2 levels in guard cells caused by exposure to light, but also abolished H2O2 that had been generated during a dark period, and promoted stomatal opening, as did ascorbic acid (ASA, an important reducing substrate for H2O2 removal). However, unlike cytokinins, auxins did not reduce exogenous H2O2, did not abolish H2O2 that had been generated in the dark, and therefore did not promote reopening of stoma induced to close in the dark. The above-mentioned effects of auxins were similar to that of diphenylene iodonium (DPI, an inhibitor of the H2O2-generating enzyme NADPH oxidase). Taken together our results indicate that cytokinins probably reduce the levels of H2O2 in guard cells by scavenging, whereas auxins limit H2O2 levels through restraining H2O2 generation, inducing stomatal opening in darkness.

2005 ◽  
Vol 32 (3) ◽  
pp. 237 ◽  
Author(s):  
Jun-Min He ◽  
Hua Xu ◽  
Xiao-Ping She ◽  
Xi-Gui Song ◽  
Wen-Ming Zhao

Previous studies have showed that UV-B can stimulate closure as well as opening of stomata. However, the mechanism of this complex effect of UV-B is not clear. The purpose of this paper is to investigate the role and the interrelationship of H2O2 and NO in UV-B-induced stomatal closure in broad bean (Vicia faba L.). By epidermal strip bioassay and laser-scanning confocal microscopy, we observed that UV-B-induced stomatal closure could be largely prevented not only by NO scavenger c-PTIO or NO synthase (NOS) inhibitor l-NAME, but also by ascorbic acid (ASC, an important reducing substrate for H2O2 removal) or catalase (CAT, the H2O2 scavenger), and that UV-B-induced NO and H2O2 production in guard cells preceded UV-B-induced stomatal closure. These results indicate that UV-B radiation induces stomatal closure by promoting NO and H2O2 production. In addition, c-PTIO, l-NAME, ASC and CAT treatments could effectively inhibit not only UV-B-induced NO production, but also UV-B-induced H2O2 production. Exogenous H2O2-induced NO production and stomatal closure were partly abolished by c-PTIO and l-NAME. Similarly, exogenous NO donor sodium nitroprusside-induced H2O2 production and stomatal closure were also partly reversed by ASC and CAT. These results show a causal and interdependent relationship between NO and H2O2 during UV-B-regulated stomatal movement. Furthermore, the l-NAME data also indicate that the NO in guard cells of Vicia faba is probably produced by a NOS-like enzyme.


2019 ◽  
Vol 46 (2) ◽  
pp. 136 ◽  
Author(s):  
Yinli Ma ◽  
Wei Zhang ◽  
Jiao Niu ◽  
Yu Ren ◽  
Fan Zhang

The roles of hydrogen sulfide (H2S) and hydrogen peroxide (H2O2) in signalling transduction of stomatal closure induced by salt stress were examined by using pharmacological, spectrophotographic and laser scanning confocal microscopic (LSCM) approaches in Vicia faba L. Salt stress resulted in stomatal closure, and this effect was blocked by H2S modulators hypotaurine (HT), aminooxy acetic acid (AOA), hydroxylamine (NH2OH), potassium pyruvate (C3H3KO3) and ammonia (NH3) and H2O2 modulators ascorbic acid (ASA), catalase (CAT), diphenylene iodonium (DPI). Additionally, salt stress induced H2S generation and increased L-/D-cysteine desulfhydrase (L-/D-CDes, pyridoxalphosphate-dependent enzyme) activity in leaves, and caused H2O2 production in guard cells, and these effects were significantly suppressed by H2S modulators and H2O2 modulators respectively. Moreover, H2O2 modulators suppressed salt stress-induced increase of H2S levels and L-/D-CDes activity in leaves as well as stomatal closure of V. faba. However, H2S modulators had no effects on salt stress-induced H2O2 production in guard cells. Altogether, our data suggested that H2S and H2O2 probably are involved in salt stress-induced stomatal closure, and H2S may function downstream of H2O2 in salt stress-induced stomatal movement in V. faba.


2011 ◽  
Vol 38 (4) ◽  
pp. 293 ◽  
Author(s):  
Jun-Min He ◽  
Zhan Zhang ◽  
Rui-Bin Wang ◽  
Yi-Ping Chen

The role of ethylene and the relationship between ethylene and nitric oxide (NO) in ultraviolet B (UV-B)-induced stomatal closure were investigated in Vicia faba L. (broad bean) plants by epidermal strip bioassay, laser-scanning confocal microscopy and assay of ethylene production. In response to UV-B radiation, the rise of NO level in guard cells was after ethylene evolution peak, but preceded stomatal closure. Both UV-B-induced NO generation in guard cells and subsequent stomatal closure were substantially inhibited not only by NO scavenger and nitrate reductase (NR) inhibitors, but also by interfering with ethylene synthesis or perception. Although exogenous NO could reverse the inhibitive effect of interfering with ethylene synthesis or perception on UV-B-induced stomatal closure, the inhibitive effect of NO scavenger and NR inhibitors on UV-B-induced stomatal closure could not be rescued by exogenous ethylene. Taken together, our results clearly show that ethylene participates in the UV-B-induced stomatal closure and acts upstream of the NR source of NO generation in V. faba.


2011 ◽  
Vol 38 (4) ◽  
pp. 303
Author(s):  
Ai-Xia Huang ◽  
Xiao-Ping She

Changes in osmotic pressure can induce stomatal closure to reduce transpirational water loss from plants. In the present work, we investigated the mechanism underlying the perception and transduction of extracellular changes in osmotic pressure in Vicia faba L. guard cells. Using an epidermal strip bioassay and laser-scanning confocal microscopy, we provide evidence that hyperosmotic stress treatment led to stomatal closure and the rapid promotion of hydrogen peroxide (H2O2) production in V. faba guard cells. The effects were largely reduced by H2O2 scavengers ASA, CAT, NADPH oxidase inhibitor DPI and cell wall peroxidase inhibitor SHAM. These results indicate that hyperosmotic stress induces stomatal closure by promoting H2O2 production. Cytochalasin B (CB), latrunculin B (Lat B) and jasplakinolide (JK) inhibited stomatal closure induced by hyperosmotic stress but didn’t prevent the increase of endogenous H2O2 levels, suggesting that microfilaments reorganisation participates in stomatal closure induced by hyperosmotic stress, and may act downstream of H2O2 signalling processes. In addition, we observed splitting of big vacuoles into many small vacuoles in response to hyperosmotic stress and H2O2 treatment, and CB inhibited these changes of vacuoles; stomatal closure was also inhibited. Taken together these results indicate that the stomatal closure in response to hyperosmotic stress may initiate H2O2 generation, and that reorganisation of microfilaments and the changing of vacuoles occurs downstream of H2O2 signalling processes.


2014 ◽  
Vol 904 ◽  
pp. 59-62 ◽  
Author(s):  
Jian Guo Li ◽  
Ying Li

The objective of this experiment was to investigate the relationship between drying and ink absorption using laser scanning confocal microscopy (LSCM). Fluorescent ink was used to observe and characterize ink penetration and distribution by LSCM. Three-dimensional images of ink penetration were obtained by reconstructing all XY plane images. Reconstructed images were used to describe ink absorption in coated paper by LSCM. The results implied that it was reliable and effective using LSCM to characterize the ink penetration depth and distribution uniformity. This method could not damage the specimen and did not need fluorescent dye to stain the specimen, which decreased the errors by hand operation. The results indicated that drying temperature affected ink penetration depth and distribution evenness. Higher and lower drying temperature could not contribute to ink absorption uniformity. With the drying temperature increasing, ink penetration depth in coated paper increased.


2010 ◽  
Vol 58 (2) ◽  
pp. 81 ◽  
Author(s):  
Xiao-Ping She ◽  
Jin Li ◽  
Ai-Xia Huang ◽  
Xi-Zhu Han

By using pharmacological approaches and laser scanning confocal microscopy based on 4,5-diaminofluorescein diacetate (DAF-2DA), the relationship between the inhibition of dark-induced stomatal closure caused by fusicoccin (FC) and the changes of nitric oxide (NO) levels in guard cells in broad bean was studied. The results show that, like 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), a NO scavenger and NG-nitro-L-Arg-methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS), FC inhibited stomatal closure induced by darkness, and reduced the levels of NO in guard cells in darkness, indicating that FC inhibits dark-induced stomatal closure through lessening NO levels in guard cells. In addition, similar to c-PTIO, both FC and butyric acid not only suppressed sodium nitroprusside (SNP)-induced stomatal closure and DAF-2DA fluorescence in guard cells, but also reopened the closed stomata induced by dark and removed NO that had been generated by dark. The results show that both FC and butyric acid cause NO removal in guard cells, and also suggest that FC-caused NO removal is probably associated with cytosolic acidification in guard cells. Taken together, our results show that FC perhaps causes cytosolic acidification in guard cells, consequently induces NO removal and reduces NO levels in guard cells, and finally inhibits stomatal closure induced by dark.


2007 ◽  
Vol 97 (11) ◽  
pp. 1491-1500 ◽  
Author(s):  
D. Macarisin ◽  
L. Cohen ◽  
A. Eick ◽  
G. Rafael ◽  
E. Belausov ◽  
...  

During the infection of citrus fruit by Penicillium digitatum there is little evidence of a host defense response. This suggests that P. digitatum has the ability to suppress host defenses. The current study demonstrates that P. digitatum suppresses a defense-related hydrogen peroxide (H2O2) burst in host tissue. In contrast, the nonhost pathogen, Penicillium expansum, triggers production of a significant amount of H2O2 in citrus fruit exocarp. Using laser scanning confocal microscopy, we demonstrated that P. digitatum suppressed an elevation in H2O2 up to 42 h after inoculation. Nevertheless, H2O2 levels around wounds inoculated with P. expansum increased by 63-fold above the control. P. digitatum continued to suppress H2O2 production in citrus fruit exocarp up to 66 h postinoculation and H2O2 levels were actually threefold below that of noninoculated controls. In contrast, the H2O2 level was still about 11-fold above the control value in wound sites inoculated with P. expansum. Studies on the effect of organic acids (as pH modulators) on the response of citrus fruit to compatible and noncompatible pathogens indicated that pathogenicity was enhanced only when host-tissue acidification was accompanied by the suppression of H2O2. Additionally, pathogenicity of both P. digitatum and P. expansum on citrus fruit was significantly enhanced by the H2O2-scavenging enzyme catalase. Based on our study and previous reports regarding the potential involvement of citric acid and catalase in green mold pathogenesis, we suggest that these compounds are strongly associated with the virulence of P. digitatum.


2021 ◽  
Vol 11 (24) ◽  
pp. 11597
Author(s):  
Jianying Zhao ◽  
Jing Qian ◽  
Ji Luo ◽  
Mingming Huang ◽  
Wenjing Yan ◽  
...  

Plasma-activated solution has attracted more attention in the food industry due to no chemical residue and good bacteriostatic properties. This study aimed to evaluate the effects of plasma-activated hydrogen peroxide solution (PAH) on the morphophysiology of Staphylococcus aureus biofilms. PAH was prepared using dielectric-barrier-discharge plasma and incubated with S. aureus biofilms for 0–40 min. Changes in biofilm morphophysiology were evaluated with laser scanning confocal microscopy, electron microscopic images, reactive oxygen species (ROS) content, metabolic capacity, and 1% agarose gel. Results indicated that the population of S. aureus in the biofilms was reduced by 4.04-log after incubation with PAH for 30 min. The thickness and metabolic capacity of biofilms were decreased, the ROS content and DNA fragments of bacteria increased after PAH treatments. Data suggested that PAH treatments significantly destroyed the morphophysiology of S. aureus (ATCC 6538) biofilms and could be considered as a valuable anti-biofilm technology to reduce foodborne pathogens on food and/or in food facilities.


2011 ◽  
Vol 59 (8) ◽  
pp. 781 ◽  
Author(s):  
XiGui Song ◽  
XiaoPing She ◽  
Juan Wang

We analysed the role and relationship between hydrogen peroxide (H2O2) reduction and the inhibition of abscisic acid (ABA)-induced stomatal closure by ethylene. Like ascorbic acid (ASA), the most important reducing substrate for H2O2 removal, catalase, one of the H2O2 scavenging enzymes and diphenylene iodonium, an inhibitor of the H2O2-generating enzyme NADPH oxidase, both ethylene-releasing compound 2-chloroethylene phosphonic acid (ethephon, ETH) and 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, were found to inhibit stomatal closure by ABA and to reduce H2O2 levels by ABA in guard cells, indicating that ethylene-caused inhibition of ABA-induced stomatal closure involves reduction of H2O2 levels in guard cells. Additionally, similar to ASA and catalase, ACC/ETH not only suppressed H2O2-induced stomatal closure and H2O2 levels in guard cells treated with exogenous H2O2 in light, but also reopened the stomata which had been closed by ABA and reduced H2O2 levels that had been generated by ABA. The abovementioned effects of ACC and ETH were dissimilar to that of diphenylene iodonium, an inhibitor of the H2O2-generating enzyme NADPH oxidase, which not only had incapability to reduce H2O2 levels by exogenous H2O2 but also could not abolish H2O2 that had been generated by ABA. So we suggest that ethylene probably induces H2O2 removal and reduces H2O2 levels in Vicia faba guard cells, and finally inhibits stomatal closure induced by ABA.


2009 ◽  
Vol 57 (6) ◽  
pp. 486 ◽  
Author(s):  
Yuanhua Zhang ◽  
Xiaoping She ◽  
Guangbin Zhang

Role and interrelationship of protein tyrosine phosphatases (PTPases) and H2O2 in light/dark-regulated stomatal movement in Vicia faba were investigated by epidermal strip bioassay, laser-scanning confocal microscopy and assays of PTPase activity. Our results indicate that phenylarsine oxide (PAO), a specific inhibitor of PTPases, ascorbic acid (ASA), an important reducing substrate for H2O2 removal, and catalase (CAT), one of the H2O2 scavenging enzymes, did not cause any change of stomatal aperture in light, but remarkably prevented dark-induced stomatal closure. Exogenous H2O2 had no obvious effect on stomatal aperture in the dark, but significantly induced stomatal closure in light. Both PTPase activity in epidermal strips and endogenous H2O2 level in guard cells in the dark were higher than those in light. The results showed that both PTPases and H2O2 mediate light/dark-regulated stomatal movement, that dark-induced stomatal closure requires the activation of PTPases and the enhancement of H2O2 levels in guard cells, and stomatal opening caused by light is associated with the inactivation of PTPases and the reduction of H2O2 levels in guard cells. Additionally, like ASA and CAT, PAO abolished dark-, exogenous H2O2-induced stomatal closure and dichlorofluorescein fluorescence in guard cells, indicating that activation of PTPases can enhance H2O2 levels probably via suppressing the decrease of H2O2 levels in guard cells. On the other hand, similar to PAO, ASA and CAT evidently prevented dark-, exogenous H2O2-induced stomatal closure and obviously inactivated PTPases in the dark. However, exogenous H2O2 significantly activated PTPases in light. The results show that H2O2 can induce activation of PTPases. Taken together, the present results provide evidence that both H2O2 and PTPases are involved in light/dark-regulated stomatal movement, and the interaction between H2O2 and PTPases plays a pivotal role in light/dark signal transduction process in guard cells.


Sign in / Sign up

Export Citation Format

Share Document