Hormones and the Orientation of Growth

Kaufman, Peter B.; Song, Il

doi:10.1007/978-94-009-3585-3_20

Cited by 43 publications

(51 citation statements)

References 29 publications

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“…Exogenous treatment of Pinus taeda with ethrel resulted in the development of many of the morphological characteristics associated with mechanical perturbation (Telewski and Jaffe, 1986). These results suggest that the increased concentration of ethylene is intimately related to gravitropism (see also Kaufman et al, 1995), resulting in CW formation. To our knowledge, our study is the first demonstration of the accumulation of an isoform of ACC oxidase in xylem-forming CW.…”

Section: Cw-responsive Proteinsmentioning

confidence: 86%

Compression Wood-Responsive Proteins in Developing Xylem of Maritime Pine (Pinus pinasterAit.),

Plomion¹,

Pionneau²,

Brach³

et al. 2000

Plant Physiology

103

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When a conifer shoot is displaced from its vertical position, compression wood (CW) is formed on the under side and can eventually return the shoot to its original position. Changes in cell wall structure and chemistry associated with CW are likely to result from differential gene/protein expression. Two-dimensional polyacrylamide gel electrophoresis of differentiating xylem proteins was combined with the physical characterization of wooden samples to identify and characterize CW-responsive proteins. Differentiating xylem was harvested from a 22-year-old crooked maritime pine (Pinus pinaster Ait.) tree. Protein extracted from different samples were revealed by high-resolution silver stained two-dimensional polyacrylamide gel electrophoresis and analyzed with a computer-assisted system for single spot quantification. Growth strain (GS) measurements allowed xylem samples to be classified quantitatively from normal wood to CW. Regression of lignin and cellulose content on GS showed that an increase in the percentage of lignin and a decrease of the percentage of cellulose corresponded to increasing GS values, i.e. CW. Of the 137 studied spots, 19% were significantly associated with GS effect. Up-regulated proteins included 1-aminocyclopropane-1-carboxylate oxidase (an ethylene forming enzyme), a putative transcription factor, two lignification genes (caffeic O-methyltransferase and caffeoyl CoA-O-methyltransferase), members of the S-adenosyl-l-methionine-synthase gene family, and enzymes involved in nitrogen and carbon assimilation (glutamine synthetase and fructokinase). A clustered correlation analysis was performed to study simultaneously protein expression along a gradient of gravistimulated stressed xylem tissue. Proteins were found to form "expression clusters" that could identify: (a) Gene product under similar control mechanisms, (b) partner proteins, or (c) functional groups corresponding to specialized pathways. The possibility of obtaining regulatory correlations and anticorrelations between proteins provide us with a new category of homology (regulatory homology) in tracing functional relationships.

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Section: Cw-responsive Proteinsmentioning

confidence: 86%

Compression Wood-Responsive Proteins in Developing Xylem of Maritime Pine (Pinus pinasterAit.),

Plomion¹,

Pionneau²,

Brach³

et al. 2000

Plant Physiology

103

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“…Differential root elongation has been postulated to arise as the consequence of a gravity-induced auxin gradient with more auxin on the lower than the upper side (Kaufman et al 1995). The factors responsible for creating the auxin gradient are not known.…”

Section: Why Is Eir1 Agravitropic?mentioning

confidence: 99%

EIR1, a root-specific protein involved in auxin transport, is required for gravitropism inArabidopsis thaliana

et al. 1998

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The EIR1 gene of Arabidopsis is a member of a family of plant genes with similarities to bacterial membrane transporters. This gene is expressed only in the root, which is consistent with the phenotypes of the eir1 mutants-the roots are agravitropic and have a reduced sensitivity to ethylene. The roots of eir1 mutants are also insensitive to the excess auxin produced by alf1-1 and fail to induce an auxin-inducible gene in the expansion zone. Although they fail to respond to internally generated auxin, they respond normally to externally applied auxin. Expression of the EIR1 gene in Saccharomyces cerevisiae confers resistance to fluorinated indolic compounds. Taken together, these data suggest that the EIR1 protein has a root-specific role in the transport of auxin.

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“…Auxin normally moves basipetally in plants. Asymmetric migration of the hormone transversally in tissues in response to unilateral light or gravity stimuli is believed to be responsible for photo-and geotropic reactions causing growth reorientation (Pickard 1985a(Pickard , 1985bKaufman et al, 1995). Whereas longitudinal transport is controlled by a preferential localization of the efflux carriers at the basal ends of cells in the transport pathway (Goldsmith, 1977;Rubery, 1987), a novel distribution of the efflux carriers at the surface of the transporting cells might account for the apparition of the lateral auxin transport in stimulated plants.…”

Section: The Efflux Carrier Activity Obeys a Complex Regulation Schemementioning

confidence: 99%

Short-Lived and Phosphorylated Proteins Contribute to Carrier-Mediated Efflux, but Not to Influx, of Auxin in Suspension-Cultured Tobacco Cells1

1998

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Auxin is transported across the plasma membrane of plant cells by diffusion and by two carriers operating in opposite directions, the influx and efflux carriers. Both carriers most likely play an important role in controlling auxin concentration and distribution in plants but little is known regarding their regulation. We describe the influence of modifications of the transmembrane pH gradient and the effect of agents interfering with protein synthesis, protein traffic, and protein phosphorylation on the activity of the auxin carriers in suspension-cultured tobacco (Nicotiana tabacum L.) cells. Carrier-mediated influx and efflux were monitored independently by measuring the accumulation of [ 14 C]2,4-dichlorophenoxyacetic acid and [ 3 H]naphthylacetic acid, respectively. The activity of the influx carrier decreased on increasing external pH and on decreasing internal pH, whereas that of the efflux carrier was only impaired on internal acidification. The efflux carrier activity was inhibited by cycloheximide, brefeldin A, and the protein kinase inhibitors staurosporine and K252a, as shown by the increased capability of treated cells to accumulate [ 3 H]naphthylacetic acid. Kinetics and reversibility of the effect of brefeldin A were consistent with one or several components of the efflux system being turned over at the plasma membrane with a half-time of less than 10 min. Inhibition of efflux by protein kinase inhibitors suggested that protein phosphorylation was essential to sustain the activity of the efflux carrier. On the contrary, the pharmacological agents used in this study failed to inhibit [ 14 C]2,4-dichlorophenoxyacetic acid accumulation, suggesting that rapidly turnedover proteins or proteins activated by phosphorylation are not essential to carrier-mediated auxin influx. Our data support the idea that the efflux carrier in plants constitutes a complex system regulated at multiple levels, in marked contrast with the influx carrier. Physiological implications of the kinetic features of this regulation are discussed.

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Hormones and the Orientation of Growth

Cited by 43 publications

References 29 publications

Compression Wood-Responsive Proteins in Developing Xylem of Maritime Pine (Pinus pinasterAit.),

Compression Wood-Responsive Proteins in Developing Xylem of Maritime Pine (Pinus pinasterAit.),

EIR1, a root-specific protein involved in auxin transport, is required for gravitropism inArabidopsis thaliana

Short-Lived and Phosphorylated Proteins Contribute to Carrier-Mediated Efflux, but Not to Influx, of Auxin in Suspension-Cultured Tobacco Cells1

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