Brassinosteroid and Hydrogen Peroxide Interdependently Induce Stomatal Opening by Promoting Guard Cell Starch Degradation

Phytophthora infestans, the most damaging oomycete pathogen of potato, is specialized to grow sporangiophore through opened stomata for secondary inoculum production. However, it is still unclear which metabolic pathways in potato are manipulated by P. infestans in the guard cell–pathogen interactions to open the stomata. Here microscopic observations and cell biology were used to investigate antagonistic interactions between guard cells and the oomycete pathogen. We observed that the antagonistic interactions started at the very beginning of infection. Stomatal movement is an important part of the immune response of potato to P. infestans infection and this occurs through guard cell death and stomatal closure. We observed that P. infestans appeared to manipulate metabolic processes in guard cells, such as triacylglycerol (TAG) breakdown, starch degradation, H2O2 scavenging, and NO catabolism, which are involved in stomatal movement, to evade these stomatal defense responses. The signal transduction pathway of P. infestans-induced stomatal opening likely starts from H2O2 and NO scavenging, along with TAG breakdown while the subsequent starch degradation reinforces the opening process by strengthening guard cell turgor and opening the stomata to their maximum aperture. These results suggest that stomata are a barrier stopping P. infestans from completing its life cycle, but this host defense system can be bypassed through the manipulation of diverse metabolic pathways that may be induced by P. infestans effector proteins.

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Ozone Altered Stomatal/Guard Cell Function: Whole Plant and Single Cell Analysis

10.32747/2000.7573082.bard ◽

2000 ◽

Author(s):

Eva J. Pell ◽

Sarah M. Assmann ◽

Amnon Schwartz ◽

Hava Steinberger

Keyword(s):

Hydrogen Peroxide ◽

Gas Exchange ◽

Vicia Faba ◽

Guard Cell ◽

Cell Function ◽

Stomatal Closure ◽

Relative Sensitivity ◽

Guard Cells ◽

Stomatal Opening ◽

K Channels

Original objectives (revisions from original proposal are highlighted) 1. Elucidate the direct effects O3 and H2O2 on guard cell function, utilizing assays of stomatal response in isolated epidermal peels and whole cell gas exchange. 2. Determine the mechanistic basis of O3 and H2O2 effects on the plasma membrane through application of the electrophysiological technique of patch clamping to isolated guard cells. 3. Determine the relative sensitivity of Israeli cultivars of economically important crops to O3 and determine whether differential leaf conductance responses to O3 can explain relative sensitivity to the air pollutant: transfer of technological expertise to Israel. Background to the topic For a long time O3 has been known to reduce gas exchange in plants; it has however been unclear if O3 can affect the stomatal complex directly. Ion channels are essential in stomatal regulation, but O3 has never before been shown to affect these directly. Major conclusions, solution, achievements 1. Ozone inhibits light-induced stomatal opening in epidermal peels isolated from Vicia faba, Arabidopsis thaliana and Nicotiana tabacum in V. faba plants this leads to reduced assimilation without a direct effect on the photosynthetic apparatus. Stomatal opening is more sensitive to O3 than stomatal closure. 2. Ozone causes inhibition of inward K+ channels (involved in stomatal opening) while no detectable effect is observed o the outward K+ channels (stomatal closure). 3. Hydrogen peroxide inhibits stomatal opening and induces stomatal closure in epidermal peels isolated from Vicia faba. 4. Hydrogen peroxide enhances stomatal closure by increasing K+ efflux from guard cells via outward rectifying K+ channels. 5. Based on epidermal peel experiments we have indirectly shown that Ca2+ may play a role in the guard cell response to O3. However, direct measurement of the guard cell [Ca2+]cyt did not show a response to O3. 6. Three Israeli cultivars of zucchini, Clarita, Yarden and Bareqet, were shown to be relatively sensitive to O3 (0.12 ml1-1 ). 7. Two environmentally important Israeli pine species are adversely affected by O3, even at 0.050 ml1-1 , a level frequently exceeded under local tropospheric conditions. P. brutia may be better equipped than P. halepensis to tolerate O3 stress. 8. Ozone directly affects pigment biosynthesis in pine seedlings, as well as the metabolism of O5 precursors, thus affecting the allocation of resources among various metabolic pathways. 9. Ozone induces activity of antioxidant enzymes, and of ascorbate content i the mesophyll and epidermis cells of Commelina communis L. Implications, both scientific and agricultural We have improved the understanding of how O3 and H2O2 do affect guard cell and stomatal function. We have shown that economical important Israeli species like zucchini and pine are relatively sensitive to O3.

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GABA signalling modulates stomatal opening to enhance plant water use efficiency and drought resilience

Nature Communications ◽

10.1038/s41467-021-21694-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Bo Xu ◽

Yu Long ◽

Xueying Feng ◽

Xujun Zhu ◽

Na Sai ◽

...

Keyword(s):

Water Use Efficiency ◽

Water Use ◽

Guard Cell ◽

Plant Stress ◽

Stomatal Opening ◽

Fine Tuning ◽

Protein Amino Acid ◽

Gaba Production ◽

Anion Transporter ◽

Use Efficiency

AbstractThe non-protein amino acid γ-aminobutyric acid (GABA) has been proposed to be an ancient messenger for cellular communication conserved across biological kingdoms. GABA has well-defined signalling roles in animals; however, whilst GABA accumulates in plants under stress it has not been determined if, how, where and when GABA acts as an endogenous plant signalling molecule. Here, we establish endogenous GABA as a bona fide plant signal, acting via a mechanism not found in animals. Using Arabidopsis thaliana, we show guard cell GABA production is necessary and sufficient to reduce stomatal opening and transpirational water loss, which improves water use efficiency and drought tolerance, via negative regulation of a stomatal guard cell tonoplast-localised anion transporter. We find GABA modulation of stomata occurs in multiple plants, including dicot and monocot crops. This study highlights a role for GABA metabolism in fine tuning physiology and opens alternative avenues for improving plant stress resilience.

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

Functional Plant Biology ◽

10.1071/fp05232 ◽

2006 ◽

Vol 33 (6) ◽

pp. 573 ◽

Cited By ~ 34

Author(s):

Xi-Gui Song ◽

Xiao-Ping She ◽

Jun-Min He ◽

Chen Huang ◽

Tu-sheng Song

Keyword(s):

Hydrogen Peroxide ◽

Vicia Faba ◽

Laser Scanning ◽

Guard Cells ◽

Laser Scanning Confocal Microscopy ◽

Stomatal Opening ◽

Scanning Confocal Microscopy ◽

Diphenylene Iodonium ◽

The Relationship ◽

Exogenous H2o2

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.

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Guard cell hydrogen peroxide and nitric oxide mediate elevated CO2-induced stomatal movement in tomato

New Phytologist ◽

10.1111/nph.13621 ◽

2015 ◽

Vol 208 (2) ◽

pp. 342-353 ◽

Cited By ~ 45

Author(s):

Kai Shi ◽

Xin Li ◽

Huan Zhang ◽

Guanqun Zhang ◽

Yaru Liu ◽

...

Keyword(s):

Nitric Oxide ◽

Hydrogen Peroxide ◽

Elevated Co2 ◽

Guard Cell ◽

Stomatal Movement

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Guard cell-specific inhibition ofArabidopsis MPK3expression causes abnormal stomatal responses to abscisic acid and hydrogen peroxide

New Phytologist ◽

10.1111/j.1469-8137.2006.01953.x ◽

2007 ◽

Vol 173 (4) ◽

pp. 713-721 ◽

Cited By ~ 106

Author(s):

Gustavo E. Gudesblat ◽

Norberto D. Iusem ◽

Peter C. Morris

Keyword(s):

Hydrogen Peroxide ◽

Abscisic Acid ◽

Guard Cell ◽

Specific Inhibition ◽

Stomatal Responses

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Guard-cell signalling for hydrogen peroxide and abscisic acid

New Phytologist ◽

10.1111/j.1469-8137.2008.02431.x ◽

2008 ◽

Vol 178 (4) ◽

pp. 703-718 ◽

Cited By ~ 193

Author(s):

Pengtao Wang ◽

Chun-Peng Song

Keyword(s):

Hydrogen Peroxide ◽

Abscisic Acid ◽

Guard Cell ◽

Cell Signalling

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Guard-Cell-Specific Expression of Phototropin2 C-Terminal Fragment Enhances Leaf Transpiration

Plants ◽

10.3390/plants11010065 ◽

2021 ◽

Vol 11 (1) ◽

pp. 65

Author(s):

Young-Sun Riu ◽

Hyun-Geun Song ◽

Hwi-Su Kim ◽

Sam-Geun Kong

Keyword(s):

Blue Light ◽

Guard Cell ◽

Ectopic Expression ◽

Stomatal Opening ◽

Chloroplast Movement ◽

35S Promoter ◽

Specific Expression ◽

Endogenous Expression ◽

Terminal Fragment ◽

Leaf Transpiration

Phototropins (phot1 and phot2) are plant-specific blue light receptors that mediate chloroplast movement, stomatal opening, and phototropism. Phototropin is composed of the N-terminus LOV1 and LOV2 domains and the C-terminus Ser/Thr kinase domain. In previous studies, 35-P2CG transgenic plants expressing the phot2 C-terminal fragment–GFP fusion protein (P2CG) under the control of 35S promoter showed constitutive phot2 responses, including chloroplast avoidance response, stomatal opening, and reduced hypocotyl phototropism regardless of blue light, and some detrimental growth phenotypes. In this study, to exclude the detrimental growth phenotypes caused by the ectopic expression of P2C and to improve leaf transpiration, we used the PHOT2 promoter for the endogenous expression of GFP-fused P2C (GP2C) (P2-GP2C) and the BLUS1 promoter for the guard-cell-specific expression of GP2C (B1-GP2C), respectively. In P2-GP2C plants, GP2C expression induced constitutive phototropin responses and a relatively dwarf phenotype as in 35-P2CG plants. In contrast, B1-GP2C plants showed the guard-cell-specific P2C expression that induced constitutive stomatal opening with normal phototropism, chloroplast movement, and growth phenotype. Interestingly, leaf transpiration was significantly improved in B1-GP2C plants compared to that in P2-GP2C plants and WT. Taken together, this transgenic approach could be applied to improve leaf transpiration in indoor plants.

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