A difference between auxin-induced and hydrogen ion-induced growth

Perley, James E.; Penny, David; Penny, Pauline

doi:10.1016/0304-4211(75)90259-x

Cited by 27 publications

(5 citation statements)

References 16 publications

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“…Using lupine hypocotyl segments, Perley et al (20) found that elongation induced by exogeneous acid was accompanied by lateral shrinkage. Taiz and Metraux (21) have shown that lateral shrinkage in response to acidic buffers can be greatly decreased or prevented by a short pretreatment with 10 mM KC1 or 2% glucose, indirectly indicating that internal osmoregulation lags behind the turgor decrease in rapidly extending segments.…”

Section: Discussionmentioning

confidence: 99%

Nonhormonal induction of H ⁺ efflux from plant tissues and its correlation with growth

Vesper¹,

Evans²

1979

Proc. Natl. Acad. Sci. U.S.A.

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When the esterase substrate a-naphthyl acetate is added to segments from coleoptiles of oat (Avena sativa L., var. Victory) or corn (Zea mays L., Bear hybrid WF 9 X 38) or to roots of lentil (Lens culinaris Med.), it is rapidly taken up and hydrolyzed to a-naphthol and acetic acid. This technique was used to generate intracellular acid and to study the effect of its efflux on growth. With corn coleoptile segments, treatment with a-naphthyl acetate induced more rapid and more prolonged growth than did exposure to external acidic buffers. Dose-response studies of a-naphthyl acetate induction of H+ secretion and growth indicated the existence of a distinct threshold rate of H+ efflux below which growth is not enhanced. The rate of H+ efflux induced by optimal levels of auxin appears to be at or below this threshold level in corn coleoptile tissue. These data indicate that the relationship between external acidification and elongation is not a simple one and that the effectiveness of H+ entering the cell wall may depend on factors not directly correlated with the appearance of H+ in the external medium.

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Section: Discussionmentioning

confidence: 99%

Nonhormonal induction of H ⁺ efflux from plant tissues and its correlation with growth

Vesper¹,

Evans²

1979

Proc. Natl. Acad. Sci. U.S.A.

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“…The theory is attractive because it provides, in a simple, direct way, a "wall-loosening factor" long hypothesized to be necessary for auxin-stimulated growth (1) and because a mass of evidence has appeared confirming the two major predictions of the theory: stimulation of growth in auxin-responsive tissue by acidic solutions without auxin (3)(4)(5)(6)(7), and stimulation of cell wall acidification by auxin (8)(9)(10)(11)(12).…”

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confidence: 99%

Vanadate inhibition of auxin-enhanced H ⁺ secretion and elongation in pea epicotyls and oat coleoptiles

Jacobs

Taiz

1980

Proc. Natl. Acad. Sci. U.S.A.

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In experiments carried out to investigate the acid secretion theory of auxin action, we utilized sodium orthovanadate, an agent found to be a selective inhibitor of a plasma membrane-associated H+-pumping ATPase in Neuros- The acid secretion theory of auxin action was proposed (1, 2) to explain auxin's dramatic stimulation of elongation in seedling stem and coleoptile tissue. It hypothesizes that the hormone's primary effect is a stimulation of an outwardly directed proton pump in the plasma membrane of target cells. This pump, when stimulated, acidifies the surrounding cell wall, loosening it either by direct breakage of acid-labile cell wall bonds or by activation of a wall-loosening enzyme located in the cell wall. The theory is attractive because it provides, in a simple, direct way, a "wall-loosening factor" long hypothesized to be necessary for auxin-stimulated growth (1) and because a mass of evidence has appeared confirming the two major predictions of the theory: stimulation of growth in auxin-responsive tissue by acidic solutions without auxin (3-7), and stimulation of cell wall acidification by auxin (8)(9)(10)(11)(12).However, despite the supportive evidence, two major questions remain. First, the mechanism of wall acidification has not yet been determined. Hager et al. (2) first proposed that auxin activates a plasma membrane ATPase which functions as a proton pump. Auxin can induce membrane hyperpolarization (13, 14) and its action is antagonized by inhibitors of ATP synthesis (8,9,15), observations consistent with the operation of an electrogenicq proton pump that utilizes ATP. However, there is no direct evidence for the participation of an ATPase in auxin-induced acidification.A second question concerns the inability of acidic buffers to mimic the long-term elongation evoked by auxin. Growth stimulation by acidic buffers lasts for only 1-2 hr, whereas auxin-induced growth continues for at least 7 hr (6). This discrepancy in the effects of acid and auxin has led some investigators to the conclusion that wall acidification cannot be a factor in long-term responses to auxin, although it may contribute to the initial response (16). It is therefore of prime importance to determine whether or not cell-wall acidification participates in long-term as well as short-term auxin-stimulated growth.The recent reports that vanadate can be a selective inhibitor of outer cell membrane ion-pumping ATPases in animal (17,18) and fungal (19) systems suggested to us that this agent might be applied to auxin-responsive higher plant tissues to help answer the above questions. In this paper we report the inhibitory effects of sodium orthovanadate upon auxin-stimulated proton secretion and elongation growth in pea epicotyls and oat coleoptiles. The effect of vanadate upon respiration and protein synthesis was also investigated in pea epicotyls. MATERIALS AND METHODSPlant Material. Pea (Pisum sativum L. cv. Alaska; FerryMorse, Mountain View, CA) and oat (Avena sativa L. var. Montezuma; California Crop Improvement ...

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“…While it is true that ion leakage occurs after shock (22), the tissue is still capable of growing rapidly when the pH is reduced (Table III). The use of acid growth to suggest that the inhibition of the auxin effect is not due to turgor changes, however, is valid only if auxin-and acid-stimulated growth are identical, a possibility with some support (2,13,17; but see also 16,23). Further evidence that osmoticum concentration remains unaffected by shock is the failure to find any differences in freezing point depression between shocked and unshocked tissues.…”

Section: Resultsmentioning

confidence: 99%

Osmotic Shock Inhibits Auxin-stimulated Acidification and Growth

Rubinstein¹

1977

Plant Physiol.

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CeUls of oat coleoptiles (Avena sativa L. cv. "Garry") have been osmotically shocked in order to observe the effect of alterations of the plasma membrane on some auxin responses. When coleoptile sections were treated sequentiaHy with 0.5 M mannitol and 1 mm Na-phosphate (pH 6.4) at 4 C, polr auxin transport and acidification by 1 mM CaCI2 were unaffected, but auxin-stimulated acidification and growth were eliminated. Shock treatment also had no effect on acid-stimulated growth or on freezing point depression by the cytoplasm. It is suggested that osmotic shock modifies a portion of the plasma membrane which interacts with auxin and eventually leads to growth.Evidence has accumulated recently which suggests that auxin interacts with a membrane as part of its physiological action (6,18). An auxin effect on the plasma membrane is implied by IAA-induced potential changes (5,14,24) as well as the stimulated uptake of K+ (8, 12), Cl-(20), a-aminoisobutyric acid, and 3-o-methyl glucose (Etherton and Rubinstein, in preparation). More direct evidence of an IAA interaction with membranes is based on the specific binding of 3H-IAA to a particulate fraction from corn coleoptiles (11). The identity of this fractionhas not yet been reported.In order to study the nature of the hormone-membrane interaction, coleoptile tissue has been osmotically shocked. In microorganisms, this treatment has been reported to inhibit uptake by releasing components of uptake systems from the membrane (9, 15). Inhibitions of uptake of selected substances after osmotic shock have also been observed in bean leaves (1) and oat coleoptiles (22), and it was suggested that the effect of shock in higher plants may be limited to modifications of the plasma membrane. This report is concerned with how the alteration of the plasma membrane by osmotic shock affects some responses to auxin. MATERIALS AND METHODSColeoptiles were isolated from etiolated seedlings of Avena sativa L. cv. "Garry"; a portion of the epidermis was removed and 5-mm sections were cut as previously described (22). The sections were osmotically shocked by first floating them for 10 min on 0.5 M mannitol and then for 10 min on 1 mm Naphosphate (pH 6.4) at 4 C.To measure auxin transport, 1-cm sections were preincubated on Na-phosphate buffer for 30 min. After shocking, a 5-mm segment was cut from the center of each section and placed basal I Supported by Grant PCM 76-00439 from the National Science Foundation.or apical end down on a 1.5% (w/w) agar receptor block. The sections (four on each receptor) were covered with a donor block containing 10 .LM '4C-IAA (52 mCi/mmol) for 90 min after which the tissue and receiver blocks were counted in scintillation fluid.Growth after 3 hr was determined optically with an ocular micrometer and dissecting microscope. Shorter term growth increments were measured with a position transducer as previously described (4, 19).The ability of sections to acidify the medium was measured in a manner similar to that of Cleland (2) and Rayle (17). Twenty pee...

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A difference between auxin-induced and hydrogen ion-induced growth

Cited by 27 publications

References 16 publications

Nonhormonal induction of H ⁺ efflux from plant tissues and its correlation with growth

Nonhormonal induction of H ⁺ efflux from plant tissues and its correlation with growth

Vanadate inhibition of auxin-enhanced H ⁺ secretion and elongation in pea epicotyls and oat coleoptiles

Osmotic Shock Inhibits Auxin-stimulated Acidification and Growth

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A difference between auxin-induced and hydrogen ion-induced growth

Cited by 27 publications

References 16 publications

Nonhormonal induction of H + efflux from plant tissues and its correlation with growth

Nonhormonal induction of H + efflux from plant tissues and its correlation with growth

Vanadate inhibition of auxin-enhanced H + secretion and elongation in pea epicotyls and oat coleoptiles

Osmotic Shock Inhibits Auxin-stimulated Acidification and Growth

Contact Info

Product

Resources

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Nonhormonal induction of H ⁺ efflux from plant tissues and its correlation with growth

Nonhormonal induction of H ⁺ efflux from plant tissues and its correlation with growth

Vanadate inhibition of auxin-enhanced H ⁺ secretion and elongation in pea epicotyls and oat coleoptiles