Control of stomatal aperture

by Araújo W. L., Fernie A. R., Nunes-Nesi A. (2011)

Wagner L Araújo,¹Alisdair R Fernie,¹ Adriano Nunes-Nesi

¹ Max-Planck Institute for Molecular Plant Physiology; Potsdam-Golm, Germany

²Departamento de Biologia Vegetal; Universidade Federal de Viçosa; Max-Planck Partner Group; MG, Viçosa, Brazil

===

In Plant Signal Behav. 6(9): 1305–1311 – doi: 10.4161/psb.6.9.16425 –

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3258058/

Abstract

Stomata, functionally specialized small pores on the surfaces of leaves, regulate the flow of gases in and out of plants. The pore is opened by an increase in osmotic pressure in the guard cells, resulting in the uptake of water. The subsequent increase in cell volume inflates the guard cell and culminates with the opening of the pore.

Although guard cells can be regarded as one of the most thoroughly investigated cell types, our knowledge of the signaling pathways which regulate guard cell function remains fragmented.

Recent research in guard cells has led to several new hypotheses, however, it is still a matter of debate as to whether guard cells function autonomously or are subject to regulation by their neighboring mesophyll cells.

This review synthesizes what is known about the mechanisms and genes critical for modulating stomatal movement. Recent progress on the regulation of guard cell function is reviewed here including the involvement of environmental signals such as light, the concentration of atmospheric CO₂ and endogenous plant hormones.

In addition we re-evaluate the important role of organic acids such as malate and fumarate play in guard cell metabolism in this process.

Manipulation of the tonoplastic organic acid transporter impacted mitochondrial metabolism, while the overall stomatal and photosynthetic capacity were unaffected

 

 

Impaired Malate and Fumarate Accumulation Due to the Mutation of the Tonoplast Dicarboxylate Transporter Has Little Effects on Stomatal Behavior

by Medeiros D. B., Barros K. A., Barros J. A. S., Omena-Garcia R. P., Arrivault S., Sanglard L. M. V. P., Detmann K. C., Silva W. B., Daloso D. M., DaMatta F. M., Nunes-Nesi A., Fernie A. R., Araújo W. L. (2017)

David B. Medeiros, Kallyne Barros, Jessica A. S. Barros, Rebeca P. Omena-Garcia, Stéphanie Arrivault, Lilian Vincis Pereira Sanglard, Kelly C. Detmann, Willian Batista Silva, Danilo M. Daloso, Fabio DaMatta, Adriano Nunes-Nesi, Alisdair R. Fernie, Wagner L Araújo,

Medeiros DB^1,2,3, Barros KA^1,2, Barros JAS^1,2, Omena-Garcia RP^1,2, Arrivault S³, Sanglard LMVP², Detmann KC², Silva WB^1,2, Daloso DM³, DaMatta FM², Nunes-Nesi A^1,2, Fernie AR³, Araújo WL².

1 Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Viçosa, Minas Gerais, Brazil.

2 Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Viçosa, Minas Gerais, Brazil.

3 Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany.

===

in Plant Physiol. 2017 Nov;175(3):1068-1081. doi: 10.1104/pp.17.00971 – Epub 2017 Sep 12 –

https://www.ncbi.nlm.nih.gov/pubmed/28899959

Abstract

Malate is a central metabolite involved in a multiplicity of plant metabolic pathways, being associated with mitochondrial metabolism and playing significant roles in stomatal movements.

Vacuolar malate transport has been characterized at the molecular level and is performed by at least one carrier protein and two channels in Arabidopsis (Arabidopsis thaliana) vacuoles.

The absence of the Arabidopsis tonoplast Dicarboxylate Transporter (tDT) in the tdt knockout mutant was associated previously with an impaired accumulation of malate and fumarate in leaves.

Here, we investigated the consequences of this lower accumulation on stomatal behavior and photosynthetic capacity as well as its putative metabolic impacts. Neither the stomatal conductance nor the kinetic responses to dark, light, or high CO₂ were highly affected in tdt plants.

In addition, we did not observe any impact on stomatal aperture following incubation with abscisic acid, malate, or citrate. Furthermore, an effect on photosynthetic capacity was not observed in the mutant lines. However, leaf mitochondrial metabolism was affected in the tdt plants.

Levels of the intermediates of the tricarboxylic acid cycle were altered, and increases in both light and dark respiration were observed.

We conclude that manipulation of the tonoplastic organic acid transporter impacted mitochondrial metabolism, while the overall stomatal and photosynthetic capacity were unaffected.

Stomatal densities drive the partitioning of conductance between leaf sides

 

 

Pore size regulates operating stomatal conductance, while stomatal densities drive the partitioning of conductance between leaf sides

by Fanourakis D., Giday H., Milla R., Pieruschka R., Kjaer K. H., Bolger M., Vasilevski A., Nunes-Nesi A., Fiorani F., Ottosen C.-O. (2015)

Dimitrios Fanourakis. Habtamu Giday. Rubén Milla, Roland Pieruschka, Katrine H. Kjaer, Marie Bolger, Aleksandar Vasilevski, Adriano Nunes-Nesi, Fabio Fiorani, Carl-Otto Ottosen,

IBG-2: Plant Sciences, Institute for Bio- and Geosciences, Forschungszentrum Jülich, D-52425 Jülich, Germany,

Aarhus University, Department of Food Science, Kirstinebjergvej 10, DK-5792 Årslev, Denmark,

Departamento de Biología y Geología, Área de Biodiversidad y Conservación, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, Móstoles 28933, Spain,

Institute for Biology I, RWTH Aachen University, Aachen, Germany and Max Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-000 Viçosa, MG, Brazil

===

in Ann. Bot.-London 115: 555–565 – https://doi.org/10.1093/aob/mcu247

CrossRef, Google Scholar – 

https://link.springer.com/article/10.1007/s11099-018-0847-z

Abstract

Background and Aims Leaf gas exchange is influenced by stomatal size, density, distribution between the leaf adaxial and abaxial sides, as well as by pore dimensions. This study aims to quantify which of these traits mainly underlie genetic differences in operating stomatal conductance (g_s) and addresses possible links between anatomical traits and regulation of pore width.

Methods Stomatal responsiveness to desiccation, g_s-related anatomical traits of each leaf side and estimated g_s (based on these traits) were determined for 54 introgression lines (ILs) generated by introgressing segments of Solanum pennelli into the S. lycopersicum‘M82’. A quantitative trait locus (QTL) analysis for stomatal traits was also performed.

Key Results A wide genetic variation in stomatal responsiveness to desiccation was observed, a large part of which was explained by stomatal length. Operating g_s ranged over a factor of five between ILs. The pore area per stomatal area varied 8-fold among ILs (2–16 %), and was the main determinant of differences in operating g_s between ILs. Operating g_s was primarily positioned on the abaxial surface (60–83 %), due to higher abaxial stomatal density and, secondarily, to larger abaxial pore area. An analysis revealed 64 QTLs for stomatal traits in the ILs, most of which were in the direction of S. pennellii.

Conclusions The data indicate that operating and maximum g_s of non-stressed leaves maintained under stable conditions deviate considerably (by 45–91 %), because stomatal size inadequately reflects operating pore area (R² = 0·46). Furthermore, it was found that variation between ILs in both stomatal sensitivity to desiccation and operating g_s is associated with features of individual stoma. In contrast, genotypic variation in g_spartitioning depends on the distribution of stomata between the leaf adaxial and abaxial epidermis.

The involvement of environmental signals such as light, the concentration of atmospheric CO2 and endogenous plant hormones in stomatal aperture

 

 

Control of stomatal aperture: a renaissance of the old guard

by Araújo W. L., Fernie A. R., Nunes-Nesi A. (2011)

Wagner L. Araújo, Universidade Federal de Viçosa (UFV), Brazil

• Alisdair R Fernie,

Adriano Nunes-Nesi, Universidade Federal de Viçosa (UFV), Brazil

in Plant Signaling & Behavior 6: 1305–1311 – DOI 10.4161/psb.6.9.16425 – 

Crossref, PubMed, Google Scholar – 

https://www.ncbi.nlm.nih.gov/pubmed/21847028

Abstract

Stomata, functionally specialized small pores on the surfaces of leaves, regulate the flow of gases in and out of plants. The pore is opened by an increase in osmotic pressure in the guard cells, resulting in the uptake of water. The subsequent increase in cell volume inflates the guard cell and culminates with the opening of the pore.

Although guard cells can be regarded as one of the most thoroughly investigated cell types, our knowledge of the signaling pathways which regulate guard cell function remains fragmented.

Recent research in guard cells has led to several new hypotheses, however, it is still a matter of debate as to whether guard cells function autonomously or are subject to regulation by their neighboring mesophyll cells.

This review synthesizes what is known about the mechanisms and genes critical for modulating stomatal movement. Recent progress on the regulation of guard cell function is reviewed here including the involvement of environmental signals such as light, the concentration of atmospheric CO2 and endogenous plant hormones.

In addition we re-evaluate the important role of organic acids such as malate and fumarate play in guard cell metabolism in this process.

Antisense inhibition of the iron-sulphur subunit of succinate dehydrogenase and stomatal aperture

Figure 14. Mitochondrial Function Triggers Stomatal Movement by Regulating Organic Acid Levels. The malate (fumarate) produced by the TCA cycle is transported to the vacuole, where it is stored. By an unclear mechanism, the level of organic acid is altered in the subsidiary cells, leading to an increased (decreased) concentration in the guard cells that culminates with the closing (opening) of stomata. Stomatal movement is additionally regulated by other well-characterized mechanisms (K+, Cl−ABA, and Ca2+); therefore, future work is required to fully understand the molecular regulatory hierarchy of this highly specialized cell type.

 

Antisense inhibition of the iron-sulphur subunit of succinate dehydrogenase enhances photosynthesis and growth in tomato via an organic acid–mediated effect on stomatal aperture

by Araújo W. L., Nunes-Nesi A., Osorio S., Usadel B., Fuentes D., Nagy R., Balbo I., Lehmann M., Studart-Witkowski C., Tohge T., Martinoia E., Jordana X., DaMatta F. M.,  Fernie A. R. (2011)

Wagner L. Araújo, Adriano Nunes-Nesi, Sonia Osorio, Björn Usadel, Daniela Fuentes, Réka Nagy, Ilse Balbo, Martin Lehmann, Claudia Studart-Witkowski, Takayuki Tohge, Enrico Martinoia, Xavier Jordana, Fábio M. DaMatta, Alisdair R. Fernie,

 

in Plant Cell 23, 600–627 – doi: 10.1105/tpc.110.081224 –

PubMed Abstract | CrossRef Full Text | Google Scholar –

http://www.plantcell.org/content/23/2/600

Abstract

Transgenic tomato (Solanum lycopersicum) plants expressing a fragment of the Sl SDH2-2 gene encoding the iron sulfur subunit of the succinate dehydrogenase protein complex in the antisense orientation under the control of the 35S promoter exhibit an enhanced rate of photosynthesis.

The rate of the tricarboxylic acid (TCA) cycle was reduced in these transformants, and there were changes in the levels of metabolites associated with the TCA cycle. Furthermore, in comparison to wild-type plants, carbon dioxide assimilation was enhanced by up to 25% in the transgenic plants under ambient conditions, and mature plants were characterized by an increased biomass.

Analysis of additional photosynthetic parameters revealed that the rate of transpiration and stomatal conductance were markedly elevated in the transgenic plants. The transformants displayed a strongly enhanced assimilation rate under both ambient and suboptimal environmental conditions, as well as an elevated maximal stomatal aperture.

By contrast, when the Sl SDH2-2 gene was repressed by antisense RNA in a guard cell–specific manner, changes in neither stomatal aperture nor photosynthesis were observed.

The data obtained are discussed in the context of the role of TCA cycle intermediates both generally with respect to photosynthetic metabolism and specifically with respect to their role in the regulation of stomatal aperture.

An increase in both stomatal and mesophyll conductance

Hypothetical model connecting the malate accumulation and stomatal movements. The functional lack of AtQUAC1 is most likely associated with an accumulation of malate inside guard cells, which consequently maintains stomatal pore aperture for a longer time. Although photosynthetic rates are increased through a mechanism not yet fully understood, this is likely related to the maintenance of a high chloroplastic CO2 concentration given that mesophyll conductance is also increased. Moreover, carbon balance and metabolism are changed through increased levels of sugars, starch, organic acids, and dark respiration rates. Altogether, increased respiration, carbohydrate pool, and photosynthesis can partially explain the observed growth enhancement in atquac1 plants.

 

Enhanced Photosynthesis and Growth in atquac1 Knockout Mutants Are Due to Altered Organic Acid Accumulation and an Increase in Both Stomatal and Mesophyll Conductance

by Medeiros D. B., Martins S. C. V., Cavalcanti J. H. F., Daloso D. M., Martinoia E., Nunes-Nesi A., Fábio M. DaMatta, Fernie A. R., Araújo W. L. (2016)

David B. Medeiros, Samuel C.V. Martins, João Henrique F. Cavalcanti, Danilo M. Daloso, Enrico Martinoia, Adriano Nunes-Nesi, Fábio M. DaMatta, Alisdair R. Fernie, Wagner L. Araújo,

=========

in Plant Physiol. 170 (1): 86-101; DOI – https://doi.org/10.1104/pp.15.01053 – 

http://www.plantphysiol.org/content/170/1/86

Abstract

Stomata control the exchange of CO₂ and water vapor in land plants. Thus, whereas a constant supply of CO₂ is required to maintain adequate rates of photosynthesis, the accompanying water losses must be tightly regulated to prevent dehydration and undesired metabolic changes. Accordingly, the uptake or release of ions and metabolites from guard cells is necessary to achieve normal stomatal function. The AtQUAC1, an R-type anion channel responsible for the release of malate from guard cells, is essential for efficient stomatal closure. Here, we demonstrate that mutant plants lacking AtQUAC1 accumulated higher levels of malate and fumarate. These mutant plants not only display slower stomatal closure in response to increased CO₂concentration and dark but are also characterized by improved mesophyll conductance. These responses were accompanied by increases in both photosynthesis and respiration rates, without affecting the activity of photosynthetic and respiratory enzymes and the expression of other transporter genes in guard cells, which ultimately led to improved growth. Collectively, our results highlight that the transport of organic acids plays a key role in plant cell metabolism and demonstrate that AtQUAC1 reduce diffusive limitations to photosynthesis, which, at least partially, explain the observed increments in growth under well-watered conditions.

Stomata are functionally specialized microscopic pores that control the essential exchange of CO₂ and H₂O with the environment in land plants. Stomata are found on the surfaces of the majority of the aerial parts of plants, rendering them as the main control point regulating the flow of gases between plants and their surrounding atmosphere. Accordingly, the majority of water loss from plants occurs through stomatal pores, allowing plant transpiration and CO₂ absorption for the photosynthetic process (Bergmann and Sack, 2007; Kim et al., 2010). The maintenance of an adequate water balance through stomatal control is crucial to plants because cell expansion and growth require tissues to remain turgid (Sablowski and Carnier Dornelas, 2014), and minor reductions in cell water volume and turgor pressure will therefore compromise both processes (Thompson, 2005). As a result, the high sensitivity of plant tissues to turgor has prompted the use of reverse genetic studies in attempt to engineer plants with improved performance (Cowan and Troughton, 1971; Xiong et al., 2009; Borland et al., 2014; Franks et al., 2015).

 

 

 

Deficiency of mitochondrial fumarase activity impairs photosynthesis via an effect on stomatal function.

 

 

Deficiency of mitochondrial fumarase activity in tomato plants impairs photosynthesis via an effect on stomatal function.

by Nunes-Nesi A., Carrari F., Gibon Y., Sulpice R., Lytovchenko A., Fisahn J.,  Graham J., Ratcliffe R. G, Sweetlove L. J, Fernie A. R. (2007)

Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Köln, Germany.

Adriano Nunes-Nesi, Universidade Federal de Viçosa (UFV), Departamento de Biologia Vegetal

Fernando Carrari, Centro Nacional de Investigaciones Agropecuarias

Yves Gibon,

Ronan Sulpice, National University of Ireland, Galway School of Natural Sciences

Anna Lytovchenko, Joachim Fisahn,  James Graham,

Richard George Ratcliffe,

Lee J. Sweetlove, University of Oxford, Department of Plant Sciences

Alisdair R. Fernie,

============================

in Plant J. 50, 1093–1106. doi: 10.1111/j.1365-313X.2007.03115.x –

PubMed Abstract | CrossRef Full Text | Google Scholar –

https://www.ncbi.nlm.nih.gov/pubmed/17461782

Abstract

Transgenic tomato (Solanum lycopersicum) plants expressing a fragment of a fumarate hydratase (fumarase) gene in the antisense orientation and exhibiting considerable reductions in the mitochondrial activity of this enzyme show impaired photosynthesis.

The rate of the tricarboxylic acid cycle was reduced in the transformants relative to the other major pathways of carbohydrate oxidation and the plants were characterized by a restricted rate of dark respiration. However, biochemical analyses revealed relatively little alteration in leaf metabolism as a consequence of reducing the fumarase activity.

That said, in comparison to wild-type plants, CO(2) assimilation was reduced by up to 50% under atmospheric conditions and plants were characterized by a reduced biomass on a whole plant basis.

Analysis of further photosynthetic parameters revealed that there was little difference in pigment content in the transformants but that the rate of transpiration and stomatal conductance was markedly reduced.

Analysis of the response of the rate of photosynthesis to variation in the concentration of CO(2) confirmed that this restriction was due to a deficiency in stomatal function.

Stomatal and mesophyll conductance, photosynthesis and growth, organic acid accumulation.

 

Enhanced photosynthesis and growth in atquac1 knockout mutants are due to altered organic acid accumulation and an increase in both stomatal and mesophyll conductance.

by Medeiros D. B., Martins S. C. V., Cavalcanti J. H. F., Daloso D. M., Martinoia E., Nunes-Nesi A., DaMatta F. M., Fernie A. R., Araujo W. L. (2016)

1. David B. Medeiros,
2. Samuel C.V. Martins,
3. João Henrique F. Cavalcanti,
4. Danilo M. Daloso,
5. Enrico Martinoia,
6. Adriano Nunes-Nesi,
7. Fábio M. DaMatta,
8. Alisdair R. Fernie 
9. Wagner L. Araújo

in Plant Physiol 170:86–101. – doi:10.1104/pp.15.01053 – 

CrossRef PubMed – 

http://www.plantphysiol.org/content/170/1/86.abstract 

Abstract

Stomata control the exchange of CO₂ and water vapor in land plants. Thus, whereas a constant supply of CO₂ is required to maintain adequate rates of photosynthesis, the accompanying water losses must be tightly regulated to prevent dehydration and undesired metabolic changes. Accordingly, the uptake or release of ions and metabolites from guard cells is necessary to achieve normal stomatal function.

The AtQUAC1, an R-type anion channel responsible for the release of malate from guard cells, is essential for efficient stomatal closure.

Here, we demonstrate that mutant plants lacking AtQUAC1 accumulated higher levels of malate and fumarate. These mutant plants not only display slower stomatal closure in response to increased CO₂ concentration and dark but are also characterized by improved mesophyll conductance.

These responses were accompanied by increases in both photosynthesis and respiration rates, without affecting the activity of photosynthetic and respiratory enzymes and the expression of other transporter genes in guard cells, which ultimately led to improved growth.

Collectively, our results highlight that the transport of organic acids plays a key role in plant cell metabolism and demonstrate that AtQUAC1 reduce diffusive limitations to photosynthesis, which, at least partially, explain the observed increments in growth under well-watered conditions.

AtQUAC1, an R-type anion channel, is essential for efficient stomatal closure.

 

Enhanced photosynthesis and growth in atquac1 knockout mutants are due to altered organic acid accumulation and an increase in both stomatal and mesophyll conductance.

Medeiros D. B., Martins S. C. V., Cavalcanti J. H. F., Daloso D., Martinoia E., Nunes-Nesi A., DaMatta F., Fernie A. R., Araujo W. (2016)

1. David B. Medeiros,
2. Samuel C.V. Martins,
3. João Henrique F. Cavalcanti,
4. Danilo M. Daloso,
5. Enrico Martinoia,
6. Adriano Nunes-Nesi,
7. Fábio M. DaMatta,
8. Alisdair R. Fernie
9. Wagner L. Araújo

in Plant Physiol 170:86–101. – doi:10.1104/pp.15.01053 – 

CrossRef PubMed – 

http://www.plantphysiol.org/content/170/1/86.abstract

Abstract

Stomata control the exchange of CO₂ and water vapor in land plants. Thus, whereas a constant supply of CO₂ is required to maintain adequate rates of photosynthesis, the accompanying water losses must be tightly regulated to prevent dehydration and undesired metabolic changes.

Accordingly, the uptake or release of ions and metabolites from guard cells is necessary to achieve normal stomatal function.

The AtQUAC1, an R-type anion channel responsible for the release of malate from guard cells, is essential for efficient stomatal closure.

Here, we demonstrate that mutant plants lacking AtQUAC1 accumulated higher levels of malate and fumarate. These mutant plants not only display slower stomatal closure in response to increased CO₂ concentration and dark but are also characterized by improved mesophyll conductance.

These responses were accompanied by increases in both photosynthesis and respiration rates, without affecting the activity of photosynthetic and respiratory enzymes and the expression of other transporter genes in guard cells, which ultimately led to improved growth.

Collectively, our results highlight that the transport of organic acids plays a key role in plant cell metabolism and demonstrate that AtQUAC1 reduce diffusive limitations to photosynthesis, which, at least partially, explain the observed increments in growth under well-watered conditions.

Stomatal conductance and stomatal density

Photo credit: Google

Pore size regulates operating stomatal conductance, while stomatal densities drive the partitioning of conductance between leaf sides

by Fanourakis D., Giday H., Milla R., Pieruschka R., Kjaer K. H., Bolger M., Vasilevski A., Nunes-Nesi A., Fiorani F., Carl-Otto Ottosen C-O. (2015)

1. Dimitrios Fanourakis,
2. Habtamu Giday,
3. Rubén Milla,
4. Roland Pieruschka,
5. Katrine H. Kjaer,
6. Marie Bolger,
7. Aleksandar Vasilevski,
8. Adriano Nunes-Nesi,
9. Fabio Fiorani
10. Carl-Otto Ottosen

in Annals of Botany, Volume 115, Issue, Pp. 555-565 – doi: 10.1093/aob/mcu247

Abstract

Background and Aims Leaf gas exchange is influenced by stomatal size, density, distribution between the leaf adaxial and abaxial sides, as well as by pore dimensions. This study aims to quantify which of these traits mainly underlie genetic differences in operating stomatal conductance (g_s) and addresses possible links between anatomical traits and regulation of pore width.

Methods Stomatal responsiveness to desiccation, g_s-related anatomical traits of each leaf side and estimated g_s (based on these traits) were determined for 54 introgression lines (ILs) generated by introgressing segments of Solanum pennelli into the S. lycopersicum ‘M82’. A quantitative trait locus (QTL) analysis for stomatal traits was also performed.

Key Results A wide genetic variation in stomatal responsiveness to desiccation was observed, a large part of which was explained by stomatal length. Operating g_s ranged over a factor of five between ILs. The pore area per stomatal area varied 8-fold among ILs (2–16 %), and was the main determinant of differences in operating g_s between ILs. Operating g_s was primarily positioned on the abaxial surface (60–83 %), due to higher abaxial stomatal density and, secondarily, to larger abaxial pore area. An analysis revealed 64 QTLs for stomatal traits in the ILs, most of which were in the direction of S. pennellii.

Conclusions The data indicate that operating and maximum g_s of non-stressed leaves maintained under stable conditions deviate considerably (by 45–91 %), because stomatal size inadequately reflects operating pore area (R² = 0·46). Furthermore, it was found that variation between ILs in both stomatal sensitivity to desiccation and operating g_s is associated with features of individual stoma. In contrast, genotypic variation in g_spartitioning depends on the distribution of stomata between the leaf adaxial and abaxial epidermis.

Read the text: Annals of Botany