Phytohormones, by F.W. Went ... and Kenneth V. Thimann ...

Thimann, Kenneth V.; Went, F. W.

doi:10.5962/bhl.title.5695

Cited by 280 publications

(412 citation statements)

References 137 publications

(215 reference statements)

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“…These results were consistent with a regulation of APRX transcription by auxin. Curvature of the growing organ is known to rise from regulated lateral auxin gradients (Went and Thimann 1937). APRX transcripts are present in the external part of the hypocotyl curvature in the zone of highest auxin concentration of the growing hypocotyls.…”

Section: Aprx Is Regulated By Auxin Levelsmentioning

confidence: 99%

“…APRX was additionally associated with a speciWc function in auxin catabolism. The phytohormone auxin is involved in diverse developmental processes, many of which depend on regulated auxin gradients (Went and Thimann 1937). For example, a gradient in auxin concentration from tip to base is believed to be responsible for diVerential elongation rates in diVerent regions of shoots (Sánchez-Bravo et al 1992).…”

Section: Aprx Is Involved In Auxin Catabolismmentioning

confidence: 99%

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An anionic class III peroxidase from zucchini may regulate hypocotyl elongation through its auxin oxidase activity

Cosio

Vuillemin

Meyer

et al. 2009

Planta

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The high number of peroxidase genes explains the description of numerous physiological functions and the fact that the in planta function of a single isoform has never been characterized yet. We analyzed in transgenic Arabidopsis thaliana the localization of a zucchini isoperoxidase (APRX), previously puriWed thanks to its pectin binding ability. We conWrmed that the protein is localized near the cell wall, mainly produced in the elongation area of the hypocotyls and respond to exogenous auxin. In addition, the ectopic overexpression of APRX induced changes in growth pattern and a signiWcant reduction of endogenous indole-3-acetic acid (IAA) level. In agreement with these observations APRX showed an elevated in vitro auxin oxidase activity. We propose that APRX participates in the negative feedback regulation of auxin level and consequently terminates the hypocotyl elongation process.

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Section: Aprx Is Regulated By Auxin Levelsmentioning

confidence: 99%

Section: Aprx Is Involved In Auxin Catabolismmentioning

confidence: 99%

An anionic class III peroxidase from zucchini may regulate hypocotyl elongation through its auxin oxidase activity

Cosio

Vuillemin

Meyer

et al. 2009

Planta

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“…Cells in the avascular tip of coleoptiles are unique and of special interest. They are the sites of auxin biogenesis, and they direct the movement of auxin (23). They themselves undergo negligible expansion growth (1), and they have important functions in the perception of stimuli (23).…”

Section: Methodsmentioning

confidence: 99%

Effects of Indoleacetic Acid on Dictyosomes of Apical and Expanding Cells of Oat Coleoptiles

Gawlik

Shen-Miller²

1974

Plant Physiol.

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We found that the auxin-induced growth is mediated through the activation of the dictyosomes (collectively, the Golgi apparatus). Incubation of oat (Avena sativa) coleoptile segments in indoleacetic acid-sucrose-phosphate buffer changes significandy the number of dictyosomes in the expanding cells. A further indication of auxin enhancement of dictyosome activity is a decrease in dictyosomal cisternae (flattened membranous sacs) number. This decrease occurred after 6 minutes of incubation in auxin, and then was followed by a reduction in the organelle number per se. These times are in keeping with the rapid action of auxin-induced cell elongaton, and the latent period of geotropism. In the apical cells, the effect of indoleacetic acid is more subtle and complex. The 3To whom reprint requests should be addressed.Individual stacks of cistemae (flattened sacs containing fluid). The association of dictyosomes within a cell forms the Golgi apparatus (14). regulated by the hormone auxin. In this study we ask whether auxin, IAA, changes the activity of the dictyosomes. And if so, are the kinetics of the changes in keeping with those of the tropistic and growth responses. We examined the quantity and activity of this organelle in the extreme apex as well as in the elongating cells of oat coleoptiles after different times of incubation in IAA solutions. MATERIALS AND METHODSPlanting and Incubation. Oat seeds (Avena sativa, Victory I) were soaked in warm tap water (initially 40 C) for 2 hr, drained, and kept in the dark for 20 hr at 4 C. The soaked seeds were then aligned, embryo up, on lucite bars covered with moist filter paper. The seeds were exposed to red light (G.E. Ruby Red tungsten filament lamp, 10 w) for 24 hr, and grown for an additional 48 hr in the dark. At the end of this period, the coleoptiles reached a length of 2 to 3 cm. The apical 1 mm, and the subapical 3 mm (4th through 6th mm) of the coleoptile were sectioned with spaced razor blades. The segments were placed in Petri dishes containing buffer, 0.1 M KH2PO4 and 2% sucrose (pH 4.6). The dishes were set on a slow reciprocating horizontal shaker for a minimum of 2 hr, in order to deplete the tissues of their endogenous auxin. The segments were then transferred to small culture dishes containing the same buffer solution with or without 1 ,M IAA (sodium salt). The dishes were then placed on the shaker, and the segments were harvested at 6-min intervals for a period of 60 min for examinations by EMS and for the determination of cell lengths. All manipulations were carried out in a dim green light (21) at 25 C and 70% relative humidity.Electron and Light Microscopy. At 6-min intervals, the segments (n = 6) were transferred to a cold fixative (approximately 4 C) containing 4% glutaraldehyde, 1 % acrolein buffered with 0.1 M Na-cacodylate to pH 7.4, and 0.1% CaCI2. Fixation was carried out in a refrigerator (4-6 C) overnight. The aldehyde-fixed segments were then washed with the same buffer in which they were fixed, and postfixed for 3 hr in cold 1 %...

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“…Asymmetric growth is thought to be controlled by changing hormone levels in different parts of graviresponding organs. Even now, asymmetric distribution of auxin, as already described by the Cholodny-Went theory (Went and Thimann 1937), is still considered to be the main causative factor for differential growth although the observed changes in free auxin levels are often rather small, non-existent or transient (Mertens and Weiler 1983;Clifford et al 1985;Schwark and Bopp 1993;Philosoph-Hadas et al 2001). Recent findings regarding the lateral relocation of the auxin efflux regulator PIN3 upon gravistimulation and the observed differential expression of a synthetic DR5::GUS auxin reporter element, however, strongly support the auxinredistribution theory (Friml et al 2002;Ottenschla¨ger et al 2003).…”

Section: Introductionmentioning

confidence: 83%

An auxin-responsive 1-aminocyclopropane-1-carboxylate synthase is responsible for differential ethylene production in gravistimulated Antirrhinum majus L. flower stems

Woltering

Балк

Nijenhuis-deVries

et al. 2004

Planta

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The regulation of gravistimulation-induced ethylene production and its role in gravitropic bending was studied in Antirrhinum majus L. cut flower stems. Gravistimulation increased ethylene production in both lower and upper halves of the stems with much higher levels observed in the lower half. Expression patterns of three different 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS) genes, an ACC oxidase (ACO) and an ethylene receptor (ETR/ERS homolog) gene were studied in the bending zone of gravistimulated stems and in excised stem sections following treatment with different chemicals. One of the ACS genes (Am-ACS3) was abundantly expressed in the bending zone cortex at the lower side of the stems within 2 h of gravistimulation. Am-ACS3 was not expressed in vertical stems or in other parts of (gravistimulated) stems, leaves or flowers. Am-ACS3 was strongly induced by indole-3-acetic acid (IAA) but not responsive to ethylene. The Am-ACS3 expression pattern strongly suggests that Am-ACS3 is responsible for the observed differential ethylene production in gravistimulated stems; its responsiveness to IAA suggests that Am-ACS3 expression reflects changes in auxin signalling. Am-ACS1 also showed increased expression in gravistimulated and IAA-treated stems although to a much lesser extent than Am-ACS3. In contrast to Am-ACS3, Am-ACS1 was also expressed in non-bending regions of vertical and gravistimulated stems and in leaves, and Am-ACS1 expression was not confined to the lower side cortex but evenly distributed over the diameter of the stem. Am-ACO and Am-ETR/ERS expression was increased in both the lower and upper halves of gravistimulated stems. Expression of both Am-ACO and Am-ETR/ERS was responsive to ethylene, suggesting regulation by IAAdependent differential ethylene production. Am-ACO expression and in vivo ACO activity, in addition, were induced by IAA, independent of the IAA-induced ethylene. IAA-induced growth of vertical stem sections and bending of gravistimulated flowering stems were little affected by ethylene or 1-methylcyclopropene treatments, indicating that the differential ethylene production plays no pivotal role in the kinetics of gravitropic bending.

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Phytohormones, by F.W. Went ... and Kenneth V. Thimann ...

Cited by 280 publications

References 137 publications

An anionic class III peroxidase from zucchini may regulate hypocotyl elongation through its auxin oxidase activity

An anionic class III peroxidase from zucchini may regulate hypocotyl elongation through its auxin oxidase activity

Effects of Indoleacetic Acid on Dictyosomes of Apical and Expanding Cells of Oat Coleoptiles

An auxin-responsive 1-aminocyclopropane-1-carboxylate synthase is responsible for differential ethylene production in gravistimulated Antirrhinum majus L. flower stems

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