The Control of Transpiration. Insights from Arabidopsis

Nilson, Sarah E.; Assmann, Sarah M.

doi:10.1104/pp.106.093161

Cited by 196 publications

(162 citation statements)

References 90 publications

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“…This suggests that stomatal hydromechanics are fundamentally different in seedless plants and seed plants: whereas the former have strictly passive control of g s in relation to water status, seed plants require metabolic or other mechanisms to amplify passive changes in guard cell turgor to overcome the epidermal mechanical advantage (Buckley, 2005). Not surprisingly, then, guard cell osmoregulation in seed plants is highly complex and adaptable (Zeiger et al, 2002;Nilson and Assmann, 2007). Our finding that BSEs can affect stomatal dynamics, together with evidence that extravascular resistance is large and dynamic Sack et al, 2005;Cochard et al, 2007) and located partly in BSEs (Scoffoni et al, 2008), suggests that BSEs may contribute to the regulatory challenges posed by seed plants' unique stomatal mechanics.…”

Section: Differences In the Hydraulic Connection Of The Epidermis Tomentioning

confidence: 99%

The Role of Bundle Sheath Extensions and Life Form in Stomatal Responses to Leaf Water Status

2011

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Bundle sheath extensions (BSEs) are key features of leaf structure with currently little-understood functions. To test the hypothesis that BSEs reduce the hydraulic resistance from the bundle sheath to the epidermis (r be ) and thereby accelerate hydropassive stomatal movements, we compared stomatal responses with reduced humidity and leaf excision among 20 species with heterobaric or homobaric leaves and herbaceous or woody life forms. We hypothesized that low r be due to the presence of BSEs would increase the rate of stomatal opening (V) during transient wrong-way responses, but more so during wrong-way responses to excision (V e ) than humidity (V h ), thus increasing the ratio of V e to V h . We predicted the same trends for herbaceous relative to woody species given greater hydraulic resistance in woody species. We found that V e , V h , and their ratio were 2.3 to 4.4 times greater in heterobaric than homobaric leaves and 2.0 to 3.1 times greater in herbaceous than woody species. To assess possible causes for these differences, we simulated these experiments in a dynamic compartment/resistance model, which predicted larger V e and V e /V h in leaves with smaller r be . These results support the hypothesis that BSEs reduce r be . Comparison of our data and simulations suggested that r be is approximately 4 to 16 times larger in homobaric than heterobaric leaves. Our study provides new evidence that variations in the distribution of hydraulic resistance within the leaf and plant are central to understanding dynamic stomatal responses to water status and their ecological correlates and that BSEs play several key roles in the functional ecology of heterobaric leaves.

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Section: Differences In the Hydraulic Connection Of The Epidermis Tomentioning

confidence: 99%

The Role of Bundle Sheath Extensions and Life Form in Stomatal Responses to Leaf Water Status

2011

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“…Although a number of genes have been identified as ABA-signaling components in guard cells, ABA metabolism inside guard cells has not been characterized (Schroeder et al, 2001;Nilson and Assmann, 2007;Wasilewska et al, 2008). It has been reported that the expression of AAO3, last step enzyme for ABA biosynthesis, is detected in guard cells of dehydrated Arabidopsis plants (Koiwai et al, 2004).…”

Section: Aba Catabolism Inside Guard Cellsmentioning

confidence: 99%

High Humidity Induces Abscisic Acid 8′-Hydroxylase in Stomata and Vasculature to Regulate Local and Systemic Abscisic Acid Responses in Arabidopsis

Okamoto

Tanaka²,

Abrams³

et al. 2008

Plant Physiol.

222

190

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Levels of endogenous abscisic acid (ABA) are changed dynamically in response to environmental conditions. The ABA 8#-hydroxylase is a key enzyme in ABA catabolism and is encoded by CYP707A genes. In this study, we examined physiological roles of Arabidopsis (Arabidopsis thaliana) CYP707As in the plant's response to changes in humidity. The cyp707a1 and cyp707a3 mutants displayed lower stomatal conductance under turgid conditions (relative humidity 60%) than the wild type. When wild-type plants were transferred to high-humidity conditions (relative humidity 90%), CYP707A1 and CYP707A3 transcript levels increased, followed by the reduction of ABA levels. The cyp707a3 mutant exhibited high ABA levels even after transferring to high-humidity conditions, whereas, under similar conditions, the cyp707a1 mutant exhibited low ABA levels comparable to the wild type. Analysis of spatial expression patterns by using transgenic plants harboring a promoter:: b-glucuronidase gene indicated that high-humidity-induced expression of CYP707A1 and CYP707A3 occurred primarily in guard cells and vascular tissues, respectively. Furthermore, stomatal closure of the cyp707a1 mutant, but not cyp707a3 mutant, was ABA hypersensitive when epidermal peel was treated with exogenous ABA, suggesting that CYP707A1 is essential for ABA catabolism inside the guard cells. These results implicate that CYP707A3 reduces the amount of mobile ABA in vascular tissues in response to high humidity, whereas CYP707A1 inactivates local ABA pools inside the guard cells. Taken together, ABA catabolism in both vascular tissues and guard cells participates in the systemic ABA action that controls stomatal movement in response to high humidity.

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“…The identification of ABA biosynthesis and signaling mutants, all of which have severely dysfunctional stomatal behavior (Tal and Nevo, 1973;Koornneef et al, 1982Koornneef et al, , 1984Mustilli et al, 2002), has firmly established the central role of this hormone in the control of gas exchange in angiosperms (Nilson and Assmann, 2007). A major avenue of research since the discovery of ABA as an active hormone in plants has been the pursuit of endogenous triggers that stimulate natural increases in this critical hormone (Wright and Hiron, 1969).…”

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confidence: 99%

Linking Turgor with ABA Biosynthesis: Implications for Stomatal Responses to Vapor Pressure Deficit across Land Plants

2016

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Stomatal responses to changes in vapor pressure deficit (VPD) constitute the predominant form of daytime gas-exchange regulation in plants. Stomatal closure in response to increased VPD is driven by the rapid up-regulation of foliar abscisic acid (ABA) biosynthesis and ABA levels in angiosperms; however, very little is known about the physiological trigger for this increase in ABA biosynthesis at increased VPD. Using a novel method of modifying leaf cell turgor by the application of external pressures, we test whether changes in turgor pressure can trigger increases in foliar ABA levels over 20 min, a period of time most relevant to the stomatal response to VPD. We found in angiosperm species that the biosynthesis of ABA was triggered by reductions in leaf turgor, and in two species tested, that a higher sensitivity of ABA synthesis to leaf turgor corresponded with a higher stomatal sensitivity to VPD. In contrast, representative species from nonflowering plant lineages did not show a rapid turgor-triggered increase in foliar ABA levels, which is consistent with previous studies demonstrating passive stomatal responses to changes in VPD in these lineages. Our method provides a new tool for characterizing the response of stomata to water availability.

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The Control of Transpiration. Insights from Arabidopsis

Cited by 196 publications

References 90 publications

The Role of Bundle Sheath Extensions and Life Form in Stomatal Responses to Leaf Water Status

The Role of Bundle Sheath Extensions and Life Form in Stomatal Responses to Leaf Water Status

High Humidity Induces Abscisic Acid 8′-Hydroxylase in Stomata and Vasculature to Regulate Local and Systemic Abscisic Acid Responses in Arabidopsis

Linking Turgor with ABA Biosynthesis: Implications for Stomatal Responses to Vapor Pressure Deficit across Land Plants

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