The plasma membrane aquaporin NtAQP1 is a key component of the leaf unfolding mechanism in tobacco

Siefritz, Franka; Otto, Beate; Bienert, Gerd Patrick; Krol, Alexander R. van der; Kaldenhoff, Ralf

doi:10.1046/j.1365-313x.2003.01947.x

Cited by 90 publications

(65 citation statements)

References 37 publications

(39 reference statements)

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“…Peeters, unpublished data), and it remains possible that one of the expansins that we have not examined in this study is important in the differential regulation of hyponastic growth. Additionally, other cell wall-loosening enzymes (for review, see Cosgrove, 1997), aquaporins (Siefritz et al, 2004), or K 1 -channels (Fuchs et al, 2003) could be differentially expressed, resulting in submergence-induced hyponastic growth of R. palustris petioles.…”

Section: Rpexpa1 Is Probably Not the Downstream Target For Regulationmentioning

confidence: 99%

The Roles of Ethylene, Auxin, Abscisic Acid, and Gibberellin in the Hyponastic Growth of Submerged Rumex palustris Petioles

et al. 2004

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Rumex palustris responds to complete submergence with upward movement of the younger petioles. This so-called hyponastic response, in combination with stimulated petiole elongation, brings the leaf blade above the water surface and restores contact with the atmosphere. We made a detailed study of this differential growth process, encompassing the complete range of the known signal transduction pathway: from the cellular localization of differential growth, to the hormonal regulation, and the possible involvement of a cell wall loosening protein (expansin) as a downstream target. We show that hyponastic growth is caused by differential cell elongation across the petiole base, with cells on the abaxial (lower) surface elongating faster than cells on the adaxial (upper) surface. Pharmacological studies and endogenous hormone measurements revealed that ethylene, auxin, abscisic acid (ABA), and gibberellin regulate different and sometimes overlapping stages of hyponastic growth. Initiation of hyponastic growth and (maintenance of) the maximum petiole angle are regulated by ethylene, ABA, and auxin, whereas the speed of the response is influenced by ethylene, ABA, and gibberellin. We found that a submergence-induced differential redistribution of endogenous indole-3-acetic acid in the petiole base could play a role in maintenance of the response, but not in the onset of hyponastic growth. Since submergence does not induce a differential expression of expansins across the petiole base, it is unlikely that this cell wall loosening protein is the downstream target for the hormones that regulate the differential cell elongation leading to submergence-induced hyponastic growth in R. palustris.

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Section: Rpexpa1 Is Probably Not the Downstream Target For Regulationmentioning

confidence: 99%

The Roles of Ethylene, Auxin, Abscisic Acid, and Gibberellin in the Hyponastic Growth of Submerged Rumex palustris Petioles

et al. 2004

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“…Moreover, many plant organs, such as leaves, cotyledons, or stems, perform extensive rhythmic growth movements, which very likely involve also considerable volume changes in nonspecialized cells (e.g. Jarillo et al, 2001;Siefritz et al, 2004), occurring within tens of minutes to hours. Cells in fast-growing plant tips-in elongation zones, including pollen tubes-are likely to fall in the same category.…”

Section: Physiological Relevancementioning

confidence: 99%

Dynamic Changes in the Osmotic Water Permeability of Protoplast Plasma Membrane

2004

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The osmotic water permeability coefficient (P f ) of plasma membrane of maize (Zea mays) Black Mexican Sweet protoplasts changed dynamically during a hypoosmotic challenge, as revealed using a model-based computational approach. The bestfitting model had three free parameters: initial P f , P f rate-of-change (slope Pf ), and a delay, which were hypothesized to reflect changes in the number and/or activity of aquaporins in the plasma membrane. Remarkably, the swelling response was delayed 2 to 11 s after start of the noninstantaneous (but accounted for) bath flush. The P f during the delay was #1 mm s 21 . During the swelling period following the delay, P f changed dynamically: within the first 15 s P f either (1) increased gradually to approximately 8 mm s 21 (in the majority population of low-initial-P f cells) or (2) increased abruptly to 10 to 20 mm s 21 and then decreased gradually to 3 to 6 mm s 21 (in the minority population of high-initial-P f cells). We affirmed the validity of our computational approach by the ability to reproduce previously reported initial P f values (including the absence of delay) in control experiments on Xenopus oocytes expressing the maize aquaporin ZmPIP2;5. Although mercury did not affect the P f in swelling Black Mexican Sweet cells, phloretin, another aquaporin inhibitor, inhibited swelling in a predicted manner, prolonging the delay and slowing P f increase, thereby confirming the hypothesis that P f dynamics, delay included, reflected the varying activity of aquaporins.The regulation of plant aquaporins is becoming a focus of research in an increasing number of laboratories Tyerman et al., 2002). However, the reports on the regulation of the water permeability of plant cells are still relatively few, very likely reflecting the technical difficulties inherent in such measurements.In order to quantify the permeability of a plant cell to water, one of the approaches consists of isolating protoplasts and monitoring the initial rate of change of their volume upon an osmotic challenge. If the osmotic potential of the external solution is changed instantaneously, the osmotic water permeability (termed P f or P os ) can be deduced from the initial rate of volume relaxation (e.g. Zhang et al., 1990;Verkman, 2000). There are at least two problems with this approach: (1) even when an instantaneous change of solution is possible, a systematic error is introduced, causing an underestimate of P f because, already during the initial phase of protoplast swelling, the volume, the surface area, and the internal concentration of solutes do not remain constant; and (2) instantaneous bath perfusion has technical-and physiological-limitations: unlike animal cells, isolated plant cell protoplasts (the terms protoplast and cell will be used here interchangeably) do not stick well to the chamber floor and defeat attempts of rapid (let alone, instantaneous) solution flushes. Very fast external solution exchange has been achieved by immobilizing the protoplast with a suction micropipette (e.g. Ramah...

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“…Physiological and genetic studies have confirmed the direct role of AQPs in improving plant water relation under salt stress (Martre et al, 2002;Siefritz et al, 2002;Siefritz et al, 2004). Sequence homology patterns have led to the classification of AQPs in most plant species into 4 subgroups: plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), nodulin-26-like intrinsic membrane proteins (NIPs), and small basic intrinsic proteins (SIPs) (Maurel et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Effects of exogenous 5-aminolevulinic acid on PIP1 and NIP aquaporin gene expression in seedlings of cucumber cultivars subjected to salinity stress

Yan¹,

Qu²,

Zhao³

et al. 2014

Genet. Mol. Res.

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The plasma membrane aquaporin NtAQP1 is a key component of the leaf unfolding mechanism in tobacco

Cited by 90 publications

References 37 publications

The Roles of Ethylene, Auxin, Abscisic Acid, and Gibberellin in the Hyponastic Growth of Submerged Rumex palustris Petioles

The Roles of Ethylene, Auxin, Abscisic Acid, and Gibberellin in the Hyponastic Growth of Submerged Rumex palustris Petioles

Dynamic Changes in the Osmotic Water Permeability of Protoplast Plasma Membrane

Effects of exogenous 5-aminolevulinic acid on PIP1 and NIP aquaporin gene expression in seedlings of cucumber cultivars subjected to salinity stress

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