Accelerated endogenous growth in Avena coleoptile segments

Cline, Morris G.; Edgerton, Mira; Rehm, Marilyn M.

doi:10.1007/bf00384933

Cited by 15 publications

(4 citation statements)

References 4 publications

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“…The growth kinetic data of stimulated and nonstimulated segments were basically the same in these experiments (Fig. IA), and were similar to those reported in previous studies (1,3,6). The only noticeable effect of this stimulation was a slight increase in the growth occurring during the 1st hr following excision, i.e.…”

supporting

confidence: 90%

Effects of Mechanical Stimulation on Avena Coleoptile Segment Elongation in a High Resolution, Continuous Growth-recording System

Haugland¹,

Cline²,

Evans³

1978

Plant Physiol.

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ABSTRACTtiles, resulting from inner epidermal stimulation, has apparently gained some degree of acceptance in the literature (1, 10, 12), the evidence for this hypothesis cannot be considered as conclusive. It seems possible that instances of enhanced growth previously attributed to mechanical effects were in fact induced by changes in auxin metabolism (4) or changes in auxin sensitivity in isolated coleoptile segments (14). In addition, the mechanical stimulation hypothesis does not take into account probable growth effects of residual auxin which must be presumed to remain in the tissue for at least a short time following excision.We have therefore reexamined the role of inner epidermal mechanical stimulation in the mediation of the IRG period as well as the effects ofmechanical stimulation on subsequent endogenous growth and on the response of excised segments to exogenously supplied IAA. MATERIALS AND METHODSPlant Material. A vena sativa L. var. Victory seeds were sown on moist paper towels in a humid container and incubated in the dark at 27 C for 60 to 72 hr at which time shoot emergence was evident. The seedlings were then given a 30-min red light treatment to suppress mesocotyl elongation. After 4 to 4.5 days coleoptiles which were 20 to 35 mm long and had outgrown their primary leaves by at least 3 mm were selected for harvesting. From each coleoptile a 10-mm segment was excised beginning 2 mm from the tip using a double-bladed cutting device.Growth Measurement. Columns of either 8 or 10 coleoptile segments were positioned in growth chambers constructed after the design of Dela Fuente and Leopold (2). The coleoptile segments were held in place in the growth chambers either by stringing on a wire as previously described (2)

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supporting

confidence: 90%

Effects of Mechanical Stimulation on Avena Coleoptile Segment Elongation in a High Resolution, Continuous Growth-recording System

Haugland¹,

Cline²,

Evans³

1978

Plant Physiol.

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“…It has long been noticed that auxin-depleted segments from coleoptiles (Cline et al 1974) or hypocotyls (Prat 1978) that were submerged in water showed initially a very low growth rate. After a while the growth rate accelerated considerably, e.g., tenfold after 3.5 h (Vesper and Evans 1979).…”

Section: The Cation Exchanger "Cell Wall" Adulterates Ph Valuesmentioning

confidence: 99%

Role of the plasma membrane H + -ATPase in auxin-induced elongation growth: historical and new aspects

Hager

2003

Journal of Plant Research

380

315

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This article will cover historical and recent aspects of reactions and mechanisms involved in the auxin-induced signalling cascade that terminates in the dramatic elongation growth of cells and plant organs. Massive evidence has accumulated that the final target of auxin action is the plasma membrane H(+)-ATPase, which excretes H(+) ions into the cell wall compartment and, in an antiport, takes up K(+) ions through an inwardly rectifying K(+) channel. The auxin-enhanced H(+) pumping lowers the cell wall pH, activates pH-sensitive enzymes and proteins within the wall, and initiates cell-wall loosening and extension growth. These processes, induced by auxin or by the "super-auxin" fusicoccin, can be blocked instantly and specifically by a voltage inhibition of the H(+)-ATPase due to removal of K(+) ions or the addition of K(+)-channel blockers. Vice versa, H(+) pumping and growth are immediately switched on by addition of K(+) ions. Furthermore, the treatment of segments either with auxin or with fusicoccin (which activates the H(+)-ATPase irreversibly) or with acid buffers (from outside) causes an identical transformation and degradation pattern of cell wall constituents during cell-wall loosening and growth. These and other results described below are in agreement with the acid-growth theory of elongation growth. However, objections to this theory are also discussed.

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“…The second, which has been referred to as the "accelerated endogenous growth effect," is initiated after about 2 hr and may last from 1 to 2 hr. The cause of this accelerated endogenous growth is unknown, but it seems to be a highly interesting phenomenon (5,6). To avoid the complicating influence of the tactile effect and the accelerated endogenous growth effect without having to use inhibitors, cAMP was added at one of three different times: (A) at zero time; (B) at or near 1 hr; (C) after 6 or 7 hr (Fig.…”

Section: Resultsmentioning

confidence: 99%

The Lack of Effect of Cyclic Adenosine 3′:5′-Monophosphate on Avena Coleoptile Growth

Edgerton¹,

Cline²,

Rehm³

1975

Plant Physiol.

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The effects of cyclic adenosine 3': 5'-monophosphate (cAMP) on the growth of Arena coleoptile segments over 4 to 10 hours were monitored with a position sensing transducer. At pH 6, cAMP (0.1 mM with and without 2.5 mM glucose; or 2 mM alone) or dibutyryl cAMP (0.1 mM) was added at the beginning of the experiment, or after about 1 hour or after about 6 or 7 hours. Under all conditions tested, cAMP compounds had little or no effect on coleoptile segment elongation. Inasmuch as cAMP does not duplicate the rapid and vigorous elongation obtained with 2 gM auxin, the hypothesis that cAMP is a mediator of auxin activity is not supported by experimental evidence in this system. This conclusion is dependent upon the assumption that the cAMP compounds penetrated the tissue.

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Accelerated endogenous growth in Avena coleoptile segments

Abstract: An unexpected acceleration in elongation of Avena coleoptile segments has been observed with a position sensor transducer 2 to 2.5 h after excision when the segments are immersed in 5 mM succinate buffer (pH 6). The cause of the accelerated growth is unknown.

Cited by 15 publications

References 4 publications

Effects of Mechanical Stimulation on Avena Coleoptile Segment Elongation in a High Resolution, Continuous Growth-recording System

Effects of Mechanical Stimulation on Avena Coleoptile Segment Elongation in a High Resolution, Continuous Growth-recording System

Role of the plasma membrane H + -ATPase in auxin-induced elongation growth: historical and new aspects

The Lack of Effect of Cyclic Adenosine 3′:5′-Monophosphate on Avena Coleoptile Growth

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