Auxin Activity of Substituted Benzoic Acids and Their Effect on Polar Auxin Transport

Keitt, G. W.; Baker, Robert A.

doi:10.1104/pp.41.10.1561

Cited by 70 publications

(44 citation statements)

References 20 publications

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“…The naphthylphthalamic acid 111-I NPA, on the other hand, has a weak ability to increase stem growth at concentrations above 106 M, which is also not shared by the other chemicals. Such weak auxin activity of NPA has previously been observed (19). It was considered possible that this activity could (20,23 (14) and 2,4-D activity (32).…”

Section: Resultsmentioning

confidence: 99%

“…7). It is concluded that these compounds, all of which are known to be auxin transport inhibitors (19,24), achieve their effects by a different mode of action from the phytotropins. The plant growth inhibitor lycoricidinol XIII has been shown to inhibit auxin transport by a mechanism different from that of the morphactins (15).…”

Section: Resultsmentioning

confidence: 99%

“…Since NPA III-1 has been described as a weak auxin (19), a possible mechanism of action could be an ability to prevent auxin action, either as a competitive inhibitor or by some other means. The auxin activity, as well as the ability to prevent auxin action, was therefore assessed on pea stem sections and compared with their ability to prevent polar auxin movement in identical pea stem sections.…”

Section: Resultsmentioning

confidence: 99%

“…(b) Where peas were used, [2-'4C]IAA-labeled transport was assessed in pea stem sections identical to those used above. In other respects, the assay was based on that used by Keitt and Baker (19). After 3 h pretreatment as described above, excess solution on the sections was removed by blotting paper, and 20 sections were placed in Perspex holders with the apical ends resting on donor planchets containing I ,Lg/ml [2-'4CJIAA (2.5 cm diameter; 1.5 ml volume;…”

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confidence: 99%

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Auxin Transport Inhibitors

Katekar

Geissler²

1980

Plant Physiol.

132

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The more active members of a proposed class of auxin transport inhibitors have been shown to have the ability to inhibit the active movement of auxin at concentrations where they have Uttle effect on auxin action and no significant auxin activity. They have also been shown to give rise to characteristic biphasic dose-response curves on cress root growth. Based on these physiological similarities and other common physiological properties, it is concluded that they may achieve their effects by a common mode of action which differs from that of other known auxin transport inhibitors. It is suggested that the name "phytotropins" be given to the class of auxin transport inhibitors now defined by a similar mode of action and common chemical properties.It has been shown that a group of chemicals which were known to affect the geotropic response can be defined by a common set of chemical requirements (16) and that these requirements are at least similar to those which can give rise to inhibition of auxin transport ( 18). The group can be divided into eight chemical types, and these are shown in Figure 1. Rules which define the chemical requirements so far known have been formulated (18). In summary, a 2-carboxyphenyl group separated by a conjugated system of atoms from a second aromatic ring may be necessary for a molecule to have high activity.At least one member of each type has been established to be an auxin transport inhibitor, as well as having the additional physiological properties of being able to abolish the root and stem geotropic responses, the phototropic response, and the apical dominance effect. From the close chemical similarity between compounds within each type, it can be inferred that members within each type may act by a similar mode of action. The broader structure-activity correlation, however, implies a relationship between the types (18). It also implies that the mode of action of the group as a whole may be different from other auxin transport inhibitors which do not conform to the chemical parameters. An investigation of this relationship, therefore, would seem warranted, especially since some compounds from within the group, e.g.NPA' III-1; CPD IV-I, and DPX 1840 VIII-I (Fig. 2), have found 'Abbreviations: CFM, methyl-2-chloro-9-hydroxyfluorene-9-carboxylate; CPD, l-(2'-carboxyphenyl)-3-phenylpropane-1,3-dione; CPP, 5-(2'-carboxyphenyl)-3-phenylpyrazole; DPX 1840, 3,3a-dihydro-2-(p-methoxyphenyl)-8H -pyrazolo(5 -1a)isoindol-8-one; NPA, N-(naphth-1-yl)-phthalamic acid; PBA, 2-(1-pyrenoyl)benzoic acid; PCIB, p-chlorophenoxyisobutyric acid; TCBA, 2,3,6-trichlorobenzoic acid; TIBA, 2,3,5-triiodobenzoic acid. use in plant physiological research, together with other auxin transport inhibitors which do not belong to the group, e.g. TIBA IX and the morphactins X (Fig. 2).To enable a class of compounds having similar physiological and chemical properties to be defined, chemicals of known high auxin transport inhibiting activity from within types II through VII were comparatively assessed for re...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Auxin Transport Inhibitors

Katekar

Geissler²

1980

Plant Physiol.

132

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“…As It has been established with certain plant systems that TIBA effectively blocks the polar transport of both applied and endogenous auxin (1,26,27) without itself being an auxin (19). In addition, it has been possible to reduce adventitious root formation by blocking the polar transport of auxin with TIBA (7,18).…”

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confidence: 99%

Meristematic Activity during Adventitious Root Primordium Development

Haissig¹

1972

Plant Physiol.

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Intact brittle willows (Salix fragilis L.) were treated so that developing adventitious root primordia in the stems would be subjected to elevated gibberellic acid or reduced endogenous auxin levels. Observations were made of primordia that were initiated during the experiments and of primordia that were established before the experiments began. The results indicated that as primordia became older and contained more cells, auxin basipetally transported in the stem seemed to be of less importance in determining cell number per primordium. Thus, established primordia depended upon this auxin to a lesser extent than primordia which were being initiated. These observations were explained on the basis of differential contributions during primordium development of cell division in the cambium of the stem and in the primordia themselves. As opposed to the effects of reduced auxin levels, applied gibberellic acid reduced the cell number per primordium most in established primordia. Initiating primordia were least affected by gibberellic acid treatment. Gibberellic acid treatment seemed mainly to reduce intraprimordium cell division, on which continued development of established primordia most depends. Seemingly, at least in brittle willow, applied gibberellic acid blocks the action of auxin in primordium development subsequent to the initiation phase.

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Apolar Embryos of Fucus Resulting From Osmotic and Chemical Treatment

Torrey

Galun

1970

American J of Botany

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Embryos of the brown alga Fucus vesiculosas L. were grown as populations in glass petri dishes in seawater at 15 C in continuous low‐intensity unilateral fluorescent illumination for periods up to 2 weeks. A quantitative estimate of increase in nuclear number was made from acetocarmine squash preparations of samples taken at 12‐or‐24 hr intervals. Over the period of 2‐6 days embryos showed a doubling time of about 12‐18 hr. Under normal seawater culture conditions each embryo formed a single rhizoid. When grown in seawater supplemented with sugar concentrations above 0.4 m, Fucus embryos developed as multicellular spherical embryos lacking rhizoids. In 0.6 m sucrose‐seawater, 97% of the embryos were apolar at 2 days; only 37% were apolar at 4 days, many having recovered from the sucrose inhibition. Some embryos remained apolar after growth in 0.6 m sucrose for 2 weeks. Nuclear counts showed that sucrose‐seawater markedly inhibited the rate of cell division. Other sugars including D‐glucose, D‐fructose, D‐galactose and the sugar alcohol D‐mannitol were also effective. When apolar embryos grown in sucrose‐seawater were returned to seawater, embryo growth resumed at the normal seawater rate, judged from nuclear counts. Such embryos formed multiple rhizoids, varying from two to eight rhizoids per embryo, which developed on the embryo quadrant or half away from the unilateral light. Each of the multiple rhizoids originated from a single small cell in the periphery of the multicellular spherica embryo. Thus the rhizoid‐forming stimulus apparently had been subdivided among a number of the cells of the apolar embryos. The implications of this finding are discussed. Attempts to produce multiple rhizoids by treatment of embryos with indoleacetic acid or 2,4‐dichlorophen‐oxyacetic acid failed. However, embryos treated with 10−4 M or 5 × 10−5 m 2,3,5‐triiodobenzoic acid formed 40 and 30% multiple rhizoids, respectively, suggesting that some chemical, perhaps hormonal, mechanism is involved in polarization and rhizoid initiation in Fucus embryogenesis.

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Auxin Activity of Substituted Benzoic Acids and Their Effect on Polar Auxin Transport

Cited by 70 publications

References 20 publications

Auxin Transport Inhibitors

Auxin Transport Inhibitors

Meristematic Activity during Adventitious Root Primordium Development

Apolar Embryos of Fucus Resulting From Osmotic and Chemical Treatment

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