On the Interaction of 2,3,5‐triiodobenzoic Acid and Maleic Hydrazide with Auxins

ÅBerg, Börje

doi:10.1111/j.1399-3054.1953.tb08948.x

Cited by 32 publications

(10 citation statements)

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“…There is thus no justification for regarding this so-called antagonistic effect as more than a purely non-specific inhibition of growth and it is interesting to note that other workers have not been able to corroborate this antagonism (Veldstra, 1953). Similar comments hold for some postulated synergisms and I suggest that the reported synergistic action of low concentrations of TIBA and IAA in the inhibition of root growth might also be a purely additive effect (Aberg, 1953). The various criteria by which we may agree to accept the existence of a true antagonism or synergism will of course vary with the type of auxin action observed (stimulation or inhibition) and the organ in which it is studied, but a full analysis of this debatable topic is not intended in this short paper.…”

Section: Dangers Of the Lack Of A Clear Idea Of What Is Meant By Antamentioning

confidence: 74%

Auxin Antagonists and Synergists. A Critical Approach*

Audus

1954

New Phytologist

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The study of the competitive action of metabolites and homologous chemical compounds in enzyme systems really started with the discovery of the competitive inhibition of succinic dehydrogenase by malonic acid. This was a purely biochemical study in a simple non-living unorganized system and demonstrated conclusively that the interaction of the two homologous compounds, succinic and malonic acids, took place at the surface of an enzyme system. The ideas underlying this phenomenon soon spread to more complex systems and have now become widely applied to the whole action of antibiotics in the grov^rth of micro-organisms. Such cell systems are relatively simple, and the application of the same principles has been of great use, not only in the elucidation of the mechanism of antibiotic action, but also in the design of new synthetic antimetabolites for inhibiting the growth of pathogenic organisms. In recent years the same ideas have been applied to the biochemical systems in which auxins are supposed to act as essential metabolites; so much so that some rather bold participants in this field of research are already talking of 'the growth enzyme' of plant cells. Thus with such a purely biochemical approach we are coming to equate more and more the growth of the cell with a simple enzymic process and trying to fit the simple relationships observed in such enzyme systems with the various plant responses obtained with auxin applications. We have even extended these considerations from the relatively simple and much studied phenomenon of extension growth, where true auxin action is observed, to such complex and as yet almost unexplored phenomena as flowering, apical dominance, tropic responses, epinasty and the like. This extension of ideas is as stimulating as it is inevitable, but as a physiologist the writer feels that great dangers of misinterpretation and wasted effort arise from too facile an approach. These dangers can be avoided only if we keep always before our eyes the full complexity of the growing cell of the higher plant.Thus in an enzyme system during the course of an experiment of normal duration the worker can usually be reasonably certain that he is dealing with material of unchanging properties, and he has always the considerable safeguard that any change in such properties may be quickly and easily detected and measured. He can thus study the substrate-inhibitor relations of the system with the utmost confidence and apply to them a rigid mathematical treatment. In the growing cell, however, the system is the very reverse of constant; indeed the very parameters of growth that are being observed as a measure of so-called ' growth reaction' are facets of the fundamental changes taking * This paper contains the substance of a lecture given at a conference on Chemical Structure and Growth Substance

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Section: Dangers Of the Lack Of A Clear Idea Of What Is Meant By Antamentioning

confidence: 74%

Auxin Antagonists and Synergists. A Critical Approach*

Audus

1954

New Phytologist

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“…That the antiauxin effects in the present sense may to some extent be caused by mechanisms other than a true competition at the sites primarily active in growth regulation has repeatedly been stressed (e.g., 3,11,102). The possibility that uncoupling effects on the oxidative phosphorylation may be partly responsible for the stimulation of wheat root growth and the allevi ation of auxin inhibition in the same material effected by several types of substances (dicoumarol, flavonoids) has recently been discussed by Stenlid (10 1).…”

Section: The Evaluation Of Growth Effectsmentioning

confidence: 97%

Stereoisomerism in Plant Growth Regulators of the Auxin Type

Fredga¹,

ÅBerg²

1965

Annu. Rev. Plant. Physiol.

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The relation between chemical structure and physiological action of the plant growth regulators of auxin type has been the object of extensive studies for three decades. Many interesting hypotheses have been suggested to ex plain the available data, but no simple explanation apt to embrace all groups of active substances has as yet been presented. The problem has been the object of several reviews (e.g., 59, 85, 105, 109, 110). Two main alternatives can be discerned in the current discussion.(a) The auxin molecules become attached to a receptor site, presumably at a protein surface, by several weak bonds (e.g., van der Waals forces, electrostatic attraction, hydrogen bridges) . The bonding is thought to be of the same type as that occurring between enzyme molecules and their sub strates. This "multipoint attachment" concept has been developed mainly by Veldstra. The "three-point attachment" hypothesis of Wain and co-work ers, assuming a bonding by the ring system (or other flat part of the mole cule) , the carboxyl group and an a-hydrogen atom in the proper steric posi tion can be regarded as a variant of the multipoint attachment concept.(b) In sharp opposition to this concept, the "two-point attachment" hypothesis of Hansch and Muir assumes a covalent bonding of the auxin molecul e to a protein receptor. The carboxyl group is thought to form a pep tide bond with the protein, while the SH-group of a cysteinyl unit reacts through a nucleophilic attack at an ortho position of the ring system with elimination of two hydrogen atoms. These reactions can hardly be assumed to proceed spontaneously, and the assumption of enzymatic catalysis would apparently bring this hypothesis in close proximity to the multi-1 The survey of literature pertaining to this review was concluded in June 1964. 2 The following abbreviations will be used: POA (phenoxyacetic acid); POB [a (phenoxy)-n-butyric acid]; POC [a-(phenoxy)-n-caproic acid]; POiB [a-(phenoxy) iSO-butyric acid]; POP [a-(phenoxy)-propionic acid]; POV [a-(phenoxy)-n-valeric acid]; substituents in the phenyl nucleus are indicated by Me (methyl), MeO (meth oxy), and by the chemical halogen symbols. Thus, 2,4-CbPOA [2,4-dichlorophenoxy acetic acid (2,4-D)], and so on. The same system is followed for the substances re lated to phenyl-imino-acetic acid (PNA); phenylacetic acid (PA); 3-indoleacetic acid (IAA); 1-and 2-naphthylacetic acid (1-and 2-NAA); 1-and 2-naphthylmethyl acetic acid (1-and 2-NMA); 3-and 2-thianaphthenylacetic acid (3-and 2-TnA); l and 2-naphthoxyacetic acid (1-and 2-NOA); 1-and 2-naphthylthioacetic acid (l and 2-NSA); and 2-naphthylselenoacetic acid (2-NSeA). 53Annu. Rev. Plant. Physiol. 1965.16:53-72. Downloaded from www.annualreviews.org Access provided by University of Nebraska -Lincoln on 04/05/15. For personal use only.Quick links to online content Further ANNUAL REVIEWS

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“…Leopold (10) figure 1 A in which the experimental points represent growth inhibition as a percentage of the controls for each concentration used. It was found that this hyperbolic response curve could be described by the equation x c-y= a + bx (1) in which c -y is the percentage inhibition (c = 100 % growth and y is the percentage value of growth for each concentration x) and a and b are constants. This equation describes a relationship analogous to that of the initial velocity equation developed for enzyme reactions (15) and later modified to include auxin-induced growth (5,12,13,14).…”

Section: Mickelson M N the Metabolism Of Glucose Bymentioning

confidence: 99%

“…It was found that higher concen tions of IAA than of 2,4-D were needed to inl growth to the same extent (fig 1 E) (fig 1 F) (fig 2 B). TIBA has been shown to interact with auxin at low concentrations to increase the stimulation of growth (1, 18), but to act as an antiauxin at high concentrations (1,6,20). In this experiment TIBA alone inhibited growth and, in combinations, enhanced the action of 2,4-D.…”

Section: Mickelson M N the Metabolism Of Glucose Bymentioning

confidence: 99%