Silicon deposition on guard cells increases stomatal sensitivity as mediated by K + efflux and consequently reduces stomatal conductance

Satisfaction of a leaf’s need for CO 2 requires an intensive gas exchange between mesophyll and atmosphere; prevention of excessive water loss demands that gas exchange be kept low. Stomata open when a low CO 2 concentration in the guard cells triggers ( a ) uptake of K + in exchange of H + , ( b ) production of organic acids, and ( c ) import of Cl - . ‘Hydropassive’ stomatal closure (i.e. turgor loss without reduction of the solute content of the guard cell) appears insufficient to protect the plant from desiccation. An additional ‘hydroactive’ solute loss is necessary; it is brought about by (+)-abscisic acid (ABA) acting as feedback messenger between mesophyll and epidermis. Stomatal closure not only curbs water loss but improves water-use efficiency because transpiration is proportional to stomatal conductance (at constant temperature). In contrast, assimilation, following saturation kinetics with respect to intercellular CO 2 , is relatively insensitive to changes in stomatal conductance (as long as stomata are wide open). In Xanthium strumarium , the amplitude of stomatal responses to ABA depends on the concentration of CO 2 in the guard cells; the opposite statement is also true. These interactions cause stomata to behave like ‘adjustable control systems’ capable of giving priority either to CO 2 assimilation or to water husbandry.

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Influence of season, drought and xylem ABA on stomatal responses to leaf-to-air vapour pressure difference of trees of the Australian wet-dry tropics

Australian Journal of Botany ◽

10.1071/bt98090 ◽

2000 ◽

Vol 48 (2) ◽

pp. 143 ◽

Cited By ~ 24

Author(s):

D. S. Thomas ◽

D. Eamus ◽

S. Shanahan

Keyword(s):

Stomatal Conductance ◽

Vapour Pressure ◽

Pressure Difference ◽

Dry Season ◽

Wet Season ◽

Stomatal Responses ◽

Dry Seasons ◽

Stomatal Sensitivity ◽

Vapour Pressure Difference ◽

Wet And Dry Seasons

This paper reports the results of two experiments undertaken to investigate the influence of season and soil drying on stomatal responses to leaf-to-air vapour pressure differences. We examined the response of stomatal conductance to increasing leaf-to-air vapour pressure difference, in the wet and dry seasons, of five tropical tree species. We also examined leaves of these species for anatomical differences to determine whether this could explain differences in stomatal sensitivity to leaf-to-air vapour pressure differences. Finally, we conducted a split-root experiment with one of those species to look for interactions between xylem abscisic acid concentration, predawn water potential, leaf area to root mass ratio and stomatal responses to leaf-to-air vapour pressure differences. Stomatal conductance declined linearly with increasing leaf-to-air vapour pressure difference in all species. Leaves that expanded in the ‘dry’ season were more sensitive to leaf-to-air vapour pressure differences than those that had expanded in the ‘wet’ season. The value of leaf-to-air vapour pressure difference where 50% of extrapolated maximum stomatal conductance would occur was 5.5 kPa for wet season but only 3.4 kPa for dry season leaves. In the wet season, transpiration rate increased with increasing leaf-to-air vapour pressure difference in most example species. However, in the dry season, transpiration was constant as leaf-to-air vapour pressure differences increased in most cases. There were significant changes in the proportion of cell wall exposed to air space in leaves, between wet and dry seasons, in three of four species examined. In the split-root experiment, a very mild water stress increased stomatal sensitivity to leaf-to-air vapour pressure differences, and stomatal conductivity declined linearly with decreasing predawn water potential. However, levels of ABA in the xylem did not change, and stomatal sensitivity to exogenous ABA did not change. The ratio of leaf area to root mass declined during water stress and was correlated to changes in stomatal sensitivity to leaf-to-air vapour pressure differences.

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Leaf anatomical characteristics associated with shoot hydraulic conductance, stomatal conductance and stomatal sensitivity to changes of leaf water status in temperate deciduous trees

Functional Plant Biology ◽

10.1071/pp00157 ◽

2001 ◽

Vol 28 (8) ◽

pp. 765 ◽

Cited By ~ 39

Author(s):

Krõõt Aasamaa ◽

Anu Sõber ◽

Märt Rahi

Keyword(s):

Stomatal Conductance ◽

Water Potential ◽

Leaf Water Potential ◽

Hydraulic Conductance ◽

Leaf Water ◽

Fourth Power ◽

Anatomical Characteristics ◽

Temperate Deciduous ◽

Stomatal Sensitivity ◽

Shoot Hydraulic Conductance

Some anatomical characteristics in leaves relating to hydraulic conductance and stomatal conductance were examined in six temperate deciduous tree species. The fourth power of the radius of the conducting elements in xylem (r4) and the area of mesophyll and epidermal cells per unit length of leaf cross-section (u) were high in leaves with high hydraulic conductance (L). Stomatal conductance (gs) and stomatal sensitivity to an increase in leaf water potential (si) correlated positively with the length of stomatal pore (l), but negatively with the guard cell width (z) and the length of the dorsal side of the guard cells (ld). Stomatal sensitivity to a decrease in leaf water potential (sd) correlated negatively with l and positively with z and ld. The anatomical characteristics associated with hydraulic conductance (r4 and u) and those associated with stomatal conductance and sensitivity to changes of leaf water potential (l, z and ld) were correlated. We conclude that hydraulic conductance may depend on anatomical characteristics of xylem, mesophyll and epidermis, and stomatal conductance and its sensitivity to changing water potential may depend on anatomical characteristics of stomata. The correlation of shoot hydraulic conductance with stomatal conductance and its sensitivity may be based largely on the correlation between the anatomical characteristics of the water conducting system and stomata in these trees.

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Effects of potassium and calcium deficiencies on stomatal functioning in intact leaves of Vicia faba

Canadian Journal of Botany ◽

10.1139/b94-225 ◽

1994 ◽

Vol 72 (12) ◽

pp. 1835-1842 ◽

Cited By ~ 6

Author(s):

Michèle Ridolfi ◽

Jean Pierre Garrec ◽

Philippe Louguet ◽

Daniel Lafray

Keyword(s):

Vicia Faba ◽

Stomatal Closure ◽

Guard Cells ◽

Calcium Deficiency ◽

X Ray ◽

Free Air ◽

Vicia Faba L ◽

Stomatal Sensitivity ◽

Cell Concentrations ◽

Stomatal Functioning

The effects of potassium or calcium deficiency on stomatal functioning were investigated in Vicia faba L. plants grown hydroponically. In the leaves of plants grown with 1 mM K+, stomatal opening occurred in light with either normal or CO2-free air; K+ and C1− accumulations in guard cells were similar to those of the control plants grown with 5 mM K+. With the zero K+ treatment, stomatal apertures were not affected, while K+ and Cl− guard cell concentrations fell to 30% of the control values. These results may indicate that other solutes contribute to the lowering of osmotic potential during opening. Stomata of calcium-deficient plants remained fully open in darkness, whereas abscisic acid (ABA) supply induced a partial stomatal closing movement. Therefore, calcium deficiency inhibited the process(es) linked with the perception of darkness and stomatal closure. On the other hand, stomatal sensitivity to ABA was only partially affected. Key words: stomatal aperture, potassium, calcium, X-ray microanalysis.

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TuMV triggers stomatal closure but reduces drought tolerance in Arabidopsis

10.1101/2020.08.03.235234 ◽

2020 ◽

Author(s):

Carlos Augusto Manacorda ◽

Gustavo Gudesblat ◽

Moira Sutka ◽

Sergio Alemano ◽

Franco Peluso ◽

...

Keyword(s):

Stomatal Conductance ◽

Drought Tolerance ◽

Time Course ◽

Stomatal Closure ◽

Guard Cells ◽

Change Scenario ◽

Daily Water ◽

Responsive Gene ◽

Non Destructive

i)SummaryIn this work the effects of TuMV infection on stomatal closure and water balance were studied in Arabidopsis. Thermal imaging analyses showed that TuMV-infected plants had consistently higher foliar temperature than mock treated controls. Non-destructive time-course experiments revealed that this differential phenotype was stable during both daytime and nighttime. This effect was due to reduced gas exchange in TuMV-infected plants, as observed through stomatal conductance and stomatal aperture assays in systemic leaves. Measurements of daily water consumption and initial dehydration rate further proved that TuMV infection reduced water loss. Salicylic acid (SA) and abscisic acid (ABA) contents were increased in TuMV-infected plants. In addition, the expression of ABI2, involved in ABA signaling, was enhanced, and ABCG40 (required for ABA transport into guard cells) was highly induced upon TuMV infection. Hypermorfic abi2-1 mutant plants, but no other ABA or SA biosynthetic, signaling or degradation mutants tested abolished both stomatal closure and low stomatal conductance phenotypes caused by TuMV. Therefore, not overall ABA levels, but localized differences in ABA import and perception in guard cells, are likely to be responsible for stomatal closure observed under TuMV infection. Plants simultaneously subjected to drought and viral stresses showed higher mortality rates than their mock-inoculated drought stressed counterparts, consistent with down-regulation of drought-responsive gene RD29A, both in short and long day conditions. Our findings indicate that in spite of stomatal closure triggered by TuMV, additional phenomena cause compromised drought tolerance of TuMV-infected Arabidopsis plants.ii)Significance statementCharacterization of the physiological responses controlling plant water management under combined stresses and the genes behind them is important in the current climate change scenario, which poses multifaceted challenges to crops. We found that TuMV infection induced ABA and SA accumulation and stomatal closure in Arabidopsis, alongside with overexpression of ABCG40 (the transporter of ABA to guard cells), whereas the dehydration-responsive gene RD29A was downregulated, concomitantly with increased plant susceptibility to drought stress under infection.

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The role of strigolactones in regulation of stomatal conductance and plant-pathogen interactions inArabidopsis thaliana

10.1101/573873 ◽

2019 ◽

Cited By ~ 3

Author(s):

Maria Kalliola ◽

Liina Jakobson ◽

Pär Davidsson ◽

Ville Pennanen ◽

Cezary Waszczak ◽

...

Keyword(s):

Gene Expression ◽

Stomatal Conductance ◽

Pseudomonas Syringae ◽

Guard Cell ◽

Stomatal Closure ◽

Cell Signalling ◽

Guard Cells ◽

Signalling Pathway ◽

Ozone Sensitivity

AbstractStrigolactones are a group of phytohormones that control shoot branching inArabidopsis thaliana. However, in recent years they have been shown to affect many other plant processes. We previously showed that the strigolactone perception mutantmore axillary branches 2 (max2)has increased susceptibility to plant pathogenic bacteria as a result of more open stomata as well as alterations in hormonal signalling. Here we show that both, strigolactone biosynthesis- (max3andmax4), and perception mutants (max2anddwarf14) are significantly more sensitive toPseudomonas syringaeDC3000. Moreover, in response toP. syringaeinfection, high levels of SA accumulated inmax2and this mutant was ozone sensitive. To search for the mechanisms that could explain pathogen- and ozone sensitivity we performed gene expression analysis and several different assays that explore the function of guard cells and regulation of guard cell signalling.Treatments with GR24 (a strigolactone analogue) resulted in very modest changes in defence-related gene expression. In contrast, guard cell function was clearly impaired inmax2and depending on the assay used, also inmax3, max4andd14mutants. Moreover, stomatal responses to stimuli that cause stomatal closure in wild-type plants (darkness, high CO2and ABA) were analysed in the strigolactone mutants. In darkness both strigolactone biosynthesis and perception mutants showed reduced stomatal closure, whereas the response to high CO2was impaired only inmax2andd14. The response to ABA was not impaired in any of the mutants. To position the role of MAX2 in the guard cell signalling network,max2was crossed with mutants defective in ABA biosynthesis (aba2), in guard cell ABA signalling (ost1) and a scaffold protein required for proper ion channel activity (ghr1). The stomatal conductance of double mutants was consistently higher than the corresponding single mutants, suggesting that MAX2 acts in a signalling pathway that functions in parallel to the well characterized guard cell ABA signalling pathway. We propose that the impaired defence responses ofmax2is related to more open stomata that allows increased entry of bacteria or air pollutants like ozone. Furthermore, as MAX2 appears to act in a specific branch of guard cell signalling (related to CO2signalling), this protein could be one of the elusive components that allow guard cells to distinguish between different environmental conditions.

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Genetic variation of stomatal conductance, blue light sensitivity and zeaxanthin content in guard cells of Pima cotton (Gossypium barbadense )

Physiologia Plantarum ◽

10.1034/j.1399-3054.1998.1030415.x ◽

1998 ◽

Vol 103 (4) ◽

pp. 560-566 ◽

Cited By ~ 5

Author(s):

Miguel A. Quiñnes ◽

Zhenmin Lu ◽

Eduardo Zeiger

Keyword(s):

Genetic Variation ◽

Stomatal Conductance ◽

Blue Light ◽

Guard Cells ◽

Light Sensitivity ◽

Gossypium Barbadense ◽

Pima Cotton

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Element content and expression of genes of interest in guard cells are connected to spatiotemporal variations in stomatal conductance

Plant Cell & Environment ◽

10.1111/pce.13644 ◽

2019 ◽

Vol 43 (1) ◽

pp. 87-102 ◽

Cited By ~ 1

Author(s):

Maxime Durand ◽

David Cohen ◽

Nathalie Aubry ◽

Cyril Buré ◽

Ivana Tomášková ◽

...

Keyword(s):

Stomatal Conductance ◽

Guard Cells ◽

Element Content ◽

Spatiotemporal Variations ◽

Expression Of Genes

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Stomatal Conductance and ABA Concentration in the Xylem Sap of Barley Lines of Contrasting Genetic Origins

Functional Plant Biology ◽

10.1071/pp96097 ◽

1997 ◽

Vol 24 (5) ◽

pp. 607 ◽

Cited By ~ 22

Author(s):

Ch. Borel ◽

Th. Simonneau ◽

D. This ◽

F. Tardieu

Keyword(s):

Stomatal Conductance ◽

Water Status ◽

Xylem Sap ◽

Cycle Duration ◽

Response Curves ◽

Hordeum Vulgare L ◽

Drought Tolerant ◽

Series Of Experiments ◽

Stomatal Sensitivity ◽

Unique Relationship

We investigated the controls of ABA concentration in the xylem sap and of stomatal conductance in five barley (Hordeum vulgare L.) lines of contrasting origins (Syrian or French), genetic backgrounds and previously field-evaluated drought resistances. Controlled water deficits were applied to young plants in a series of experiments in the greenhouse with contrasting evaporative demands. There was a unique relationship between soil water status and the concentration of ABA in the xylem sap measured at the end of the night. This relationship applied to all experiments for a given line, and was common between lines. Concentrations measured in the sap collected by pressurising leaves were similar to those in the sap of pressurised roots. Stomatal conductance was related to the concentration of ABA in the sap, with relationships which were common for all experiments within each line. Response curves of gs to concentration of ABA in the sap differed among two groups of lines which slightly differed in life cycle duration. Apparent stomatal sensitivity to ABAwas lower in earliest anthesing lines. Both groups comprised lines of either Syrian or French origins, and either ‘drought tolerant’ or ‘drought susceptible’ lines. We conclude that stomatal control had a low genetic variability in the studied range of lines, in spite of the large genetic differences between lines.

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A Scanning Electron Microscope Study of Isolated Guard Cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007271x ◽

1973 ◽

Vol 31 ◽

pp. 454-455 ◽

Cited By ~ 1

Author(s):

P. Dayanandan ◽

P. B. Kaufman

Keyword(s):

Electron Microscope ◽

Electron Microscope Study ◽

Three Dimensional ◽

Guard Cells ◽

Scanning Electron Microscope Study ◽

Psilotum Nudum ◽

Subsidiary Cells ◽

Welwitschia Mirabilis ◽

Cycas Revoluta ◽

Scanning Electron

A three dimensional appreciation of the guard cell morphology coupled with ultrastjuctural studies should lead to a better understanding of their still obscure dynamics of movement. We have found the SEM of great value not only in studies of the surface details of stomata but also in resolving the structures and relationships that exist between the guard and subsidiary cells. We now report the isolation and SEM studies of guard cells from nine genera of plants.Guard cells were isolated from the following plants: Psilotum nudum, four species of Equisetum, Cycas revoluta, Ceratozamia sp., Pinus sylvestris, Ephedra cochuma, Welwitschia mirabilis, Euphorbia tirucalli and Allium cepa.

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