Distinct Abscisic Acid Signaling Pathways for Modulation of Guard Cell versus Mesophyll Cell Potassium Channels Revealed by Expression Studies in <i>Xenopus laevis</i>Oocytes

Sutton, Fedora; Paul, Sunil S.; Wang, Xi-Qing; Assmann, Sarah M.

doi:10.1104/pp.124.1.223

Cited by 37 publications

(27 citation statements)

References 40 publications

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“…Some early ABA signal transduction components exist in animals, suggesting that ABA signaling mechanisms may be even more broadly conserved than previously thought (63). We are currently testing whether La 3ϩ can modulate ABA activation of PLD in plasma membrane fractions (60).…”

Section: Resultsmentioning

confidence: 93%

ABI5 Interacts with Abscisic Acid Signaling Effectors in Rice Protoplasts

Gampala¹,

Finkelstein²,

Sun³

et al. 2002

Journal of Biological Chemistry

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Abscisic acid (ABA) regulates seed maturation, germination, and adaptation of vegetative tissues to environmental stresses. The mechanisms of ABA action and the specificity conferred by signaling components in overlapping pathways are not completely understood. The ABI5 gene (ABA insensitive 5) of Arabidopsis encodes a basic leucine zipper factor required for ABA response in the seed and vegetative tissues. Using transient gene expression in rice protoplasts, we provide evidence for the functional interactions of ABI5 with ABA signaling effectors VP1 (viviparous 1) and ABI1 (ABA insensitive 1). Co-transformation experiments with ABI5 cDNA constructs resulted in specific transactivation of the ABA-inducible wheat Em, Arabidopsis AtEm6, bean ␤-Phaseolin, and barley HVA1 and HVA22 promoters. Furthermore, ABI5 interacted synergistically with ABA and co-expressed VP1, indicating that ABI5 is involved in ABA-regulated transcription mediated by VP1. ABI5-mediated transactivation was inhibited by overexpression of abi1-1, the dominant-negative allele of the protein phosphatase ABI1, and by 1-butanol, a competitive inhibitor of phospholipase D involved in ABA signaling. Lanthanum, a trivalent ion that acts as an agonist of ABA signaling, potentiated ABI5 transactivation. These results demonstrate that ABI5 is a key target of a conserved ABA signaling pathway in plants.Abscisic acid (ABA) 1 is one of the major plant hormones and functions in regulation of seed maturation, germination, and adaptation of vegetative tissues to environmental stresses (1, 2). ABA acts to effect changes on multiple physiological processes such as inducing the rapid closure of stomatal pores to limit transpiration and by triggering slower changes in gene expression (see Refs. 3-5 for reviews). Although these disparate processes share genetic elements (some ABA mutants affect both processes) and signaling intermediates such as phospholipases, cADP-ribose, inositol 1,4,5-trisphosphate, and calcium ions (6 -9), these secondary messengers are not specific to ABA pathways. Our knowledge of separate yet overlapping ABA and stress signal transduction pathways is fragmentary.Genetic analyses (10, 11) of germination processes in Arabidopsis have resulted in map-based cloning of the ABA-insensitive genes, ABI1-5 (12-19). The ABI1 and ABI2 genes encode homologous type 2C protein Ser/Thr phosphatases (PP2Cs) with partially redundant but distinct tissue-specific negative regulator functions in the regulation of ABA-, cold-, or droughtinducible genes and ion channels (20 -24). The original mutant alleles, abi1-1 and abi2-1, are both missense mutations of a conserved Gly-to-Asp mutation (G180D in abi1-1 and G168D in abi2-1) that results in a dominant phenotype in vivo and reduced phosphatase activity in vitro. The substrates for ABAregulatory protein phosphatases 2C are not known (15,16, 25).The ABI3, ABI4, and ABI5 genes encode proteins belonging to three distinct classes of transcription factors: the basic B3 domain, APETALA2 domain, and the basic leucine ...

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Section: Resultsmentioning

confidence: 93%

ABI5 Interacts with Abscisic Acid Signaling Effectors in Rice Protoplasts

Gampala¹,

Finkelstein²,

Sun³

et al. 2002

Journal of Biological Chemistry

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“…To date, regulation of guard cell ion transport by ABA, particular ABA inhibition of a guard cell inward K + current is well documented [23], but knowledge about up-regulation of the events and signaling chains remains very incomplete. Recent findings have illustrated that external and internal ABA can induce H 2 O 2 generation in guard cells [7], [24].…”

Section: Discussionmentioning

confidence: 99%

K+ channels inhibited by hydrogen peroxide mediate abscisic acid signaling in Vicia guard cells

Zhang

et al. 2001

Cell Res

100

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A number of studies show that environmental stress conditions increase abscisic acid (ABA) and hydrogen peroxide (H 2 O 2 ) levels in plant cells. Despite this central role of ABA in altering stomatal aperture by regulating guard cell ion transport, little is known concerning the relationship between ABA and H 2 O 2 in signal transduction leading to stomatal movement. Epidermal strip bioassay illustrated that ABA-inhibited stomatal opening and ABA-induced stomatal closure were abolished partly by externally added catalase (CAT) or diphenylene iodonium (DPI), which are a H 2 O 2 scavenger and a NADPH oxidase inhibitor respectively. In contrast, internally added CAT or DPI nearly completely or partly reversed ABA-induced closure in half-stoma. Consistent with these results, whole-cell patch-clamp analysis showed that intracellular application of CAT or DPI partly abolished ABA-inhibited inward K + current across the plasma membrane of guard cells. H 2 O 2 mimicked ABA to inhibit inward K + current, an effect which was reversed by the addition of ascorbic acid (Vc) in patch clamping micropipettes. These results suggested that H 2 O 2 mediated ABA-induced stomatal movement by targeting inward K + channels at plasma membrane.

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“…Results shown in Table 2 indicate that ERECTA, which is known to regulate transpiration by reducing stomatal density (Masle et al, 2005), was upregulated, while KAT1, which encodes an inward potassium channel in guard cells that regulate stomatal behavior (Liu et al, 2000;Sutton et al, 2000), was downregulated in the mutant shoots. RGAL, encoding a RGAlike DELLA protein that is a negative regulator of GA signaling (Wen and Chang, 2002;Fu and Harberd, 2003;Achard et al, 2006), and IAA28, which negatively regulates lateral root formation (Rogg et al, 2001), were downregulated in the mutant roots.…”

Section: Analysis Of Transcript Levels Of Stress-responsive Genes Andmentioning

confidence: 99%

Activated Expression of anArabidopsisHD-START Protein Confers Drought Tolerance with Improved Root System and Reduced Stomatal Density

et al. 2008

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Drought is one of the most important environmental constraints limiting plant growth and agricultural productivity. To understand the underlying mechanism of drought tolerance and to identify genes for improving this important trait, we conducted a gain-of-function genetic screen for improved drought tolerance in Arabidopsis thaliana. One mutant with improved drought tolerance was isolated and designated as enhanced drought tolerance1. The mutant has a more extensive root system than the wild type, with deeper roots and more lateral roots, and shows a reduced leaf stomatal density. The mutant had higher levels of abscisic acid and Pro than the wild type and demonstrated an increased resistance to oxidative stress and high levels of superoxide dismutase. Molecular genetic analysis and recapitulation experiments showed that the enhanced drought tolerance is caused by the activated expression of a T-DNA tagged gene that encodes a putative homeodomain-START transcription factor. Moreover, overexpressing the cDNA of the transcription factor in transgenic tobacco also conferred drought tolerance associated with improved root architecture and reduced leaf stomatal density. Therefore, we have revealed functions of the homeodomain-START factor that were gained upon altering its expression pattern by activation tagging and provide a key regulator that may be used to improve drought tolerance in plants.

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Distinct Abscisic Acid Signaling Pathways for Modulation of Guard Cell versus Mesophyll Cell Potassium Channels Revealed by Expression Studies in Xenopus laevisOocytes

Cited by 37 publications

References 40 publications

ABI5 Interacts with Abscisic Acid Signaling Effectors in Rice Protoplasts

ABI5 Interacts with Abscisic Acid Signaling Effectors in Rice Protoplasts

K+ channels inhibited by hydrogen peroxide mediate abscisic acid signaling in Vicia guard cells

Activated Expression of anArabidopsisHD-START Protein Confers Drought Tolerance with Improved Root System and Reduced Stomatal Density

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