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Epidermis over the white part of a T. albiflora leaf as viewed by the CCD camera in bright field (left) or Chi fluorescence illumination (right). During an experiment, light from the guard cells' chloroplasts would be directed to the photomultiplier by moving the stage to bring the stomate into the central black square seen in bright field.
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A procedure for following changes in the steady-state yield of chlorophyll a fluorescence (F(s)) from single guard cell pairs in variegated leaves of Tradescantia albiflora is described. As an indicator of photosynthetic electron transport, F(s) is a very sensitive indirect measure of the balance of adenosine 5'-triphosphate (ATP) and reduced nicot...
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In its leaf blade, Arundinella hirta has unusual Kranz cells that lie distant from the veins (distinctive cells; DCs), in addition to the usual Kranz units composed of concentric layers of mesophyll cells (MCs) and bundle sheath cells (BSCs; usual Kranz cells) surrounding the veins. We examined whether chlorophyllous organs other than leaf blades--...
Citations
... To capture guard cell ATP concentration, Buckley et al. (2003) adopted the model proposed by Farquhar and Wong (1984), in which ATP concentration is described by ATP production through the light reaction electron transport chain, and ATP consumption through the Calvin cycle and the photorespiration pathway. The authors based this statement on the assumption that ATP concentrations are controlled by similar processes in guard cells and mesophyll cells, but acknowledge the conflicting evidence that exists on Calvin cycle activity within guard cells (Cardon and Berry, 1992;Lawson et al., 2002;Outlaw Jr., 1989). ATP concentration within the guard cell was thus linked with photosynthetic activity and responded to environmental perturbations such as changes in temperature, light level, and CO 2 concentrations. ...
... Values are mean ± SE, n = 3 the activity of a number of Calvin-Benson cycle enzymes and ATP synthase via the ferredoxin/thioredoxin system, the changes in light intensity within minutes may be critical for CO 2 assimilation in the Calvin-Benson cycle [which includes ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), chloroplast fructose-1, 6-bisphosphatase (FBPase), sedoheptulose-1,7-bisphosphatase (SBPase), phosphoribulokinase (PRK)] (Kirschbaum and Pearcy 1988;Pearcy 1992, 1994). Light fluctuation for several tens of minutes may affect stomatal conductance (Cardon and Berry 1992;Lawson et al. 2002;Morison 1998). Because these reactions affect photosynthesis as a whole, drastic fluctuations in light intensity can cause photoinhibition and reduce plant growth (Kono et al. 2014;Tikkanen and Aro 2012;Yamori et al. 2016a). ...
Plants in natural environments must cope with diverse, highly dynamic, and unpredictable conditions. They have mechanisms to enhance the capture of light energy when light intensity is low, but they can also slow down photosynthetic electron transport to prevent the production of reactive oxygen species and consequent damage to the photosynthetic machinery under excess light. Plants need a highly responsive regulatory system to balance the photosynthetic light reactions with downstream metabolism. Various mechanisms of regulation of photosynthetic electron transport under stress have been proposed, however the data have been obtained mainly under environmentally stable and controlled conditions. Thus, our understanding of dynamic modulation of photosynthesis under dramatically fluctuating natural environments remains limited. In this review, first I describe the magnitude of environmental fluctuations under natural conditions. Next, I examine the effects of fluctuations in light intensity, CO2 concentration, leaf temperature, and relative humidity on dynamic photosynthesis. Finally, I summarize photoprotective strategies that allow plants to maintain the photosynthesis under stressful fluctuating environments. The present work clearly showed that fluctuation in various environmental factors resulted in reductions in photosynthetic rate in a stepwise manner at every environmental fluctuation, leading to the conclusion that fluctuating environments would have a large impact on photosynthesis.
... Linear electron transport (Hipkins et al., 1983;Shimazaki and Zeiger, 1985;Cardon and Berry, 1992;Tsionsky et al., 1997;Lawson et al., 2002Lawson et al., , 2003 and carbon fixation (Lawson, 2009) take place in guard cell chloroplasts. Previous studies have examined the roles of photosynthesis in stomatal responses, however most of these studies have focused on effects of mesophyll photosynthesis (Lee and Bowling, 1992;Baroli et al., 2008), or could not distinguish Stomatal apertures in response to [CO 2 ] changes were measured in wildtype (WT) and GC-ChlaseDN plants. ...
... Linear electron transport (Hipkins et al., 1983;Shimazaki and Zeiger, 1985;Cardon and Berry, 1992;Tsionsky et al., 1997;Lawson et al., 2002Lawson et al., , 2003 and carbon fixation (Lawson, 2009) take place in guard cell chloroplasts. Previous studies have examined the roles of photosynthesis in stomatal responses, however most of these studies have focused on effects of mesophyll photosynthesis (Lee and Bowling, 1992;Baroli et al., 2008), or could not distinguish Stomatal apertures in response to [CO 2 ] changes were measured in wildtype (WT) and GC-ChlaseDN plants. ...
Stomatal pores are responsible for >95% of plant water loss. CO2 levels in leaves are determined by respiration, photosynthesis, stomatal conductance and atmospheric [CO2]. [CO2] in leaves regulates stomatal movements. The role of guard-cell photosynthesis and starch-biosynthesis in stomatal conductance responses is a matter of debate, and genetic approaches are needed. To study the role of guard-cell photosynthesis in stomatal conductance, transgenic plants that lack chlorophyll specifically in guard cells were generated and analyzed. The results suggests that CO2-induced stomatal closure is not directly mediated by guard-cell photosynthesis/electron transport (1). Moreover, approximately 45% of the stomata in these lines were deflated showing a previously not-described “thin-shaped” stomatal morphology, which suggests a key function of guard-cell photosynthesis for energization and turgor production of stomatal guard cells (1). To study whether starch-biosynthesis in guard cells and/or in mesophyll cells is rate-limiting for high CO2-induced stomatal closing. Stomatal CO2 responses and CO2 assimilation-rates of defined starch-biosynthesis mutants (ADGase, pPGI) were conducted. Data reveal that starch-synthesis in guard cells but not mesophyll functions in CO2-induced stomatal closure.
... Linear electron transport (Hipkins et al., 1983;Shimazaki and Zeiger, 1985;Cardon and Berry, 1992;Tsionsky et al., 1997;Lawson et al., 2002Lawson et al., , 2003 and carbon fixation (Lawson, 2009) take place in guard cell chloroplasts. Previous studies have examined the roles of photosynthesis in stomatal responses, however most of these studies have focused on effects of mesophyll photosynthesis (Lee and Bowling, 1992;Baroli et al., 2008), or could not distinguish Stomatal apertures in response to [CO 2 ] changes were measured in wildtype (WT) and GC-ChlaseDN plants. ...
Stomata mediate gas exchange between the inter-cellular spaces of leaves and the atmosphere. CO2 levels in leaves (Ci) are determined by respiration, photosynthesis, stomatal conductance and atmospheric [CO2]. [CO2] in leaves mediates stomatal movements. The role of guard-cell photosynthesis in stomatal conductance responses is a matter of debate, and genetic approaches are needed. We have generated transgenic Arabidopsis plants that are chlorophyll-deficient in guard cells only, expressing a constitutively active chlorophyllase in a guard-cell specific enhancer trap-line. Our data show that more than 90% of guard cells were chlorophyll-deficient. Interestingly, approximately ~ 45% of stomata had an unusual, previously not-described, morphology of thin-shaped chlorophyll-less stomata. Nevertheless, stomatal size, stomatal index, plant morphology, and whole-leaf photosynthetic parameters (PSII, qP, qN, FV’/FM’) were comparable to wild-type plants. Time-resolved intact leaf gas exchange analyses showed a reduction in stomatal conductance and carbon assimilation rates of the transgenic plants. Normalization of CO2 responses showed that stomata of transgenic plants respond to [CO2] shifts. Detailed stomatal aperture measurements of normal kidney-shaped stomata, which lack chlorophyll, showed stomatal closing responses to [CO2] elevation and abscisic acid (ABA), while thin-shaped stomata were continuously closed. Our present findings show that stomatal movement responses to [CO2] and ABA are functional in guard cells that lack chlorophyll. These data suggest that guard-cell CO2 and ABA signal transduction are not directly modulated by guard-cell photosynthesis/electron transport. Moreover, the finding that chlorophyll-less stomata cause a “deflated” thin-shaped phenotype, suggests that photosynthesis in guard cells is critical for energization and guard-cell turgor production. This article is protected by copyright. All rights reserved.
... Linear electron transport (Hipkins et al., 1983;Shimazaki and Zeiger, 1985;Cardon and Berry, 1992;Tsionsky et al., 1997;Lawson et al., 2002Lawson et al., , 2003 and carbon fixation (Lawson, 2009) take place in guard cell chloroplasts. Previous studies have examined the roles of photosynthesis in stomatal responses, however most of these studies have focused on effects of mesophyll photosynthesis (Lee and Bowling, 1992;Baroli et al., 2008), or could not distinguish Stomatal apertures in response to [CO 2 ] changes were measured in wildtype (WT) and GC-ChlaseDN plants. ...
Stomatal pores are responsible for >95% of plant water loss. CO2 levels in leaves are determined by respiration, photosynthesis, stomatal conductance and atmospheric [CO2]. Increased CO2 levels in leaves causes stomatal closing. Mesophyll and guard cells fix CO2 into carbohydrates, which are then stored in the chloroplasts as starch. The role of guard-cell photosynthesis and starch-biosynthesis in stomatal conductance responses is a matter of debate, and genetic approaches are needed. To study the role of guard-cell photosynthesis in stomatal conductance, transgenic plants that lack chlorophyll specifically in guard cells were generated and analyzed. The results suggest that CO2- induced stomatal closure is not directly mediated by guard-cell photosynthesis/electron transport (1). Moreover, approximately 45% of the stomata in these lines were deflated showing a previously not-described “thin-shaped” stomatal morphology, which suggests a key function of guard-cell photosynthesis for energization and turgor production of stomatal guard cells (1). To study whether starch-biosynthesis in guard cells and/or in mesophyll cells is rate-limiting for high CO2-induced stomatal closing. Stomatal CO2 responses and CO2 assimilation-rates of defined starch-biosynthesis mutants (ADGase, pPGI) were conducted. Data reveal that starch-synthesis in guard cells but not mesophyll functions in CO2-induced stomatal closure.
... Otherwise, variations of light intensity within minutes may be critical for CO 2 fixation in the CBC. Fluctuations of light with the cycle of dozen minutes to hours may be an important factor, which influence stomata conductance (Cardon and Berry 1992;Willmer and Fricker 1996;Morison 1998;Lawson et al. 2002). ...
... A 0 , the amplitude of the EPR spectrum of fusinite particles injected into the leaf equilibrated with air. Modified Fig. 3 from Ligeza et al. (1997) 2008; Iwai et al. 2010a;Kirchhoff et al. 2011;Nagy et al. 2011Nagy et al. , 2013Los et al. 2013;Garab 2014), stomata opening/closure (Cardon and Berry 1992;Willmer and Fricker 1996;Morison 1998;Lawson et al. 2002), and relocation of chloroplasts within the plant cell (avoidance effects, see for review Kasahara et al. 2002;Takagi 2003;Wada et al. 2003;Kong and Wada 2011). ...
Regulation of photosynthetic electron transport at different levels of structural and functional organization of photosynthetic apparatus provides efficient performance of oxygenic photosynthesis in plants. This review begins with a brief overview of the chloroplast electron transport chain. Then two noninvasive biophysical methods (measurements of slow induction of chlorophyll a fluorescence and EPR signals of oxidized P700 centers) are exemplified to illustrate the possibility of monitoring induction events in chloroplasts in vivo and in situ. Induction events in chloroplasts are considered and briefly discussed in the context of short-term mechanisms of the following regulatory processes: (i) pH-dependent control of the intersystem electron transport; (ii) the light-induced activation of the Calvin-Benson cycle; (iii) optimization of electron transport due to fitting alternative pathways of electron flow and partitioning light energy between photosystems I and II; and (iv) the light-induced remodeling of photosynthetic apparatus and thylakoid membranes.
... The majority of guard cells contain functional chloroplasts (Humble & Raschke, 1971;Willmer & Fricker, 1996); Paphiopedilum species is one of the exceptions to this rule, having no chloroplasts but functional stomata (Nelson & Mayo, 1975;Willmer & Fricker, 1996). It has also been known for many years that linear electron transport takes place in the guard cell chloroplasts (Hipkins et al., 1983;Shimazaki & Zeiger, 1985;Willmer & Fricker, 1996;Cardon & Berry, 1992;Tsionsky et al., 1997;Lawson et al., 2002Lawson et al., , 2003 although high numbers and activity of Photosystem I (Lurie, 1977) have been thought to indicate high rates of cyclic electron flow and supporting the notion that ATP production potentially provides the energy required for plasma membrane proton pumps (Shimazaki & Zeiger, 1985;Tominaga et al., 2001) required for ion uptake. Alternatively, the energy and reductant produced from electron transport (ATP & NADPH) could be used for the reduction of oxaloacetate (OAA) and malate production from starch degradation (Outlaw, 2003) which has been correlated with an increase in stomatal aperture (Imamura, 1943;Yamashita, 1952;Fischer, 1968;Fischer & Hsiao, 1968;Humble & Raschke, 1971;Allaway, 1973;Pearson, 1973;Outlaw & Lowry, 1977;Shimada et al., 1979;Outlaw, 1983;Asai et al., 2000). ...
The definitive version is available at http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-8137
Stomata control gaseous fluxes between the internal leaf air spaces and the external atmosphere. Guard cells determine stomatal aperture and must operate to ensure an appropriate balance between CO2 uptake for photosynthesis (A) and water loss, and ultimately plant water use efficiency (WUE). A strong correlation between A and stomatal conductance (gs) is well documented and often observed, but the underlying mechanisms, possible signals and metabolites that promote this relationship are currently unknown. In this review we evaluate the current literature on mesophyll-driven signals that may coordinate stomatal behaviour with mesophyll carbon assimilation. We explore a possible role of various metabolites including sucrose and malate (from several potential sources; including guard cell photosynthesis) andnew evidence that improvements in WUE have been made by manipulating sucrose metabolism within the guard cells. Finally we discuss the new tools and techniques available for potentially manipulating cell-specific metabolism, including guard and mesophyll cells, in order to elucidate mesophyll-derived signals that coordinate mesophyllCO2 demands with stomatal behaviour, in order to provide a mechanistic understanding of these processes as this may identify potential targets for manipulations in order to improve plant WUE and crop yield.
... An alternative hypothesis to explain the inhibitory effect of high CO 2 concentration on isoprene emission is the regulation of isoprene synthesis pathway by the availability of ATP and NADPH (Rasulov et al. 2009). There is a positive correlation between ATP level and isoprene emission (Loreto and Sharkey 1993), and the pool size of ATP is lower under higher than under ambient [CO 2 ] (Cardon and Berry 1992; Sharkey 1993). Furthermore, Rasulov et al. (2009) demonstrated that isoprene emission was inhibited by both high and very low CO 2 concentration (below ca. ...
Biogenic volatile organic compounds (BVOCs) produced by trees participate in the formation of air pollutants such as ozone and particulate matter. At the same time, the metabolic processes responsible for these emissions are sensitive to ozone and other air pollutants, as well as the solar radiation flux, which is affected by atmospheric particulate concentration. Recent anthropogenic increases in the atmospheric carbon dioxide concentration are also capable of affecting BVOC emissions, although the mechanisms behind these responses can produce variable effects depending on the plant species. Mechanisms of air pollutant effects on BVOC emissions are reviewed and dose-response relationships across a variety of trees with differing pollutant tolerance and emission capacity are compared. From this broad analysis, generalized response patterns have been developed. This chapter emphasizes the need to consider the interactions between BVOC emissions and ozone to understand plant behaviour in future climates.
... 5.507-fold and ?5.151-fold for carbonic anhydrase after 30 days in shoots and roots, respectively; ?7.398-fold for Rubisco in roots after 30 days) (Tables 4, 5). Rubisco is known for its involvement in the Calvin cycle for carbon fixation (Cardon and Berry 1992). Moreover, carbonic anhydrase, an enzyme that requires zinc, catalyzes the reversible hydration of carbon dioxide, thus facilitating its transfer and fixation (Ramanan and others 2009). ...
Despite its high capacity to take up nitrate from soil, winter rapeseed (Brassica napus) is characterized by a low N recovery in seeds. Thus, to maintain yield, rapeseed requires a high fertilization rate. Increasing nutrient use efficiency in rapeseed by addition of a biostimulant could help improve its agroenvironmental balance. The effects of marine brown seaweed Ascophyllum nodosum on plant growth have been well described physiologically. However, to our knowledge, no study has focused on transcriptomic analyses to determine metabolic targets of these extracts. A preliminary screening of different extracts revealed a significant effect of one of them (AZAL5) on rapeseed root (+102 %) and shoot ( 23 %) growth. Microarray analysis was then used on AZAL5-treated or nontreated plants to characterize changes in gene expression that were further supported by physiological evidence. Stimulation of nitrogen uptake (+21 and +115 % in shoots and roots, respectively) and assimilation was increased in a similar manner to growth, whereas sulfate content (+63 and +133 % in shoots and roots, respectively) was more strongly stimulated leading to sulfate accumulation. Among the identified genes whose expression was affected by AZAL5, MinE, a plastid division regulator, was the most strongly affected. Its effect was supported by microscopic analysis showing an enhancement of chloroplast number per cell and starch content but without a significant difference in net photosynthetic rate. In conclusion, it is suggested that AZAL5, which promotes plant growth and nutrient uptake, could be used as a supplementary tool to improve rapeseed agroenvironmental balance.
