Β-indolylacetic Acid Research Articles

A new method for the determination of inulin in plasma and urine

A new rapid and convenient method is described for the determination of inulin in plasma and urine. The determination is based on the formation of a purple-violet color by fructose with β-indolylacetic acid in concentrated hydrochloric acid. Some advantages of the new method are discussed.

Studies in the Regeneration of Horseradish

Regeneration has been studied in fragments of various sizes, and complete plants, together with the effect of externally-applied β-indolylacetic acid (I.A.A.). The main conclusions are as follows: (1) In the intact plant regeneration is inhibited by the growing crown; in cuttings, I.A.A. will reduce the rate of primordium-formation, but cannot entirely suppress it. (2) The bud/root ratio among differentiated primordia is about 0·5–0·9 in long cuttings; it rises sharply in cuttings less than 2 cm. long, and falls in the presence of I.A.A. Most, though probably not all, of the observations concerning this ratio can be explained on a simple auxin-level hypothesis. (3) I.A.A., at an appropriate concentration, depresses the extension of buds and promotes that of roots. On each cutting, only one (proximal) bud will normally extend—but this form of dominance cannot be exactly simulated by I.A.A., and more than one hormone seems to be involved. The results are discussed from the point of view of hormone theories of regeneration, and it is concluded that direct measurements of internal auxin-content will be essential before the phenomena can be interpreted with consistency.

Factors Controlling Meristematic Activity in Excised Roots. V Effects of β‐indolylacetic Acid, β‐indolylacetonitrile and α‐(l‐naphthylmethylsulphide)‐propionic acid on the Growth and Survival of Roots of Lycopersicum esculentum, Mill

Factors Controlling Meristematic Activity in Excised Roots. V Effects of β‐indolylacetic Acid, β‐indolylacetonitrile and α‐(l‐naphthylmethylsulphide)‐propionic acid on the Growth and Survival of Roots of <i>Lycopersicum esculentum</i>, Mill

A growth interaction between B-indolylacetic acid and thiourea (thiocarbamide).

IN experiments designed to explain the activities of 3-indolylacetonitrile recently isolated by Jones, Henbest, Smith and Bentley1 from brussels sprouts, Osborne2 has shown evidence for synergism between this compound and heteroauxin (β-indolylacetic acid). The experiments were carried out on pea tissue, and the degree of curvature of split pea cotyledons measured in accordance with the standard Went pea curvature test3.

Growth-Regulating Effect of Certain Organic Compounds

SINCE the discovery that β-indolylacetic acid and other organic compounds are active in regulating growth and development in the plant, much research has been directed toward the elucidation of the mechanism of regulation. This research has followed several lines, one being the attempt to correlate physiological activity with chemical structure1–4. It has been postulated that certain features of molecular Structure and configuration are required for activity. Koepfli, Thimann and Went1 suggest that these features are an unsaturated ring system and a side-chain carrying a carboxyl group at least one carbon atom removed from the ring. After an analysis of many compounds, Veldstra2 re-orientates these requirements as a basal ring system with high surface activity and a carboxyl group in a very definite spatial position with respect to this ring system. The discussion has been carried further by Muir et al.3, who postulate that, at least for the phenoxyacetic acids, “the position on the benzene ring adjacent to the point of attachment of the side-chain is directly involved in the growth reaction”; that is, if the compound is to have activity, at least one of the ortho positions needs to be free.

Production of gliotoxin by penicillium terlikowskii Zal.

A Penicillium producing gliotoxin, isolated from Wareham Heath soil, has been identified as P. Terlikowskii Zal. Culture filtrates from this mould developed greater fungistatic activity on Raulin-Thom and Weindling media than on Czapek-Dox or a Corn-steep medium. In Weindling, a wide variety of carbon sources may be used and ammonium, peptone and nitrate nitrogen is suitable as a nitrogen source. The initial pH of the medium should be above pH 4·0. An impurity in a crude grade of glucose used in some of the culture media was found to increase sporulation and to stimulate greatly development of fungistatic activity in culture filtrates. It has not been found possible to associate this effect with various minor elements (iron, copper, zinc, manganese, molybdenum), calcium, various vitamins (aneurin, nicotinic acid, riboflavin, inositol, pyridoxin, β-indolyl acetic acid), peptone or yeast extract. There is considerable variation in the capacity to produce gliotoxin among strains of P. Terlikowskii; a common sterile mycelial variant, though vigorous in growth, produces little, if any, gliotoxin. The possible significance of gliotoxin as a factor concerned in the maintenance of microbiological equilibria in soil is discussed.

Plant-Growth Substances as Selective Weed-Killers: Inhibition of Plant Growth by 2:4-Dichlorophenoxyacetic Acid and other Plant-Growth Substances

THE work on this subject began at Rothamsted in November 1941 as a result of the previous study of the deformation of legume root hairs made by H. K. Chen, which indicated that the curling of root hairs by Rhizobium was due to the secretion by the latter of β-indolylacetic acid. Our first experiments were intended to discover whether a similar deformation of root hairs could be induced by β-indolylacetic acid itself and by related plant stimulants.

The detection and determination of auxins in organic manures. Part II.—Extraction of auxins from manures, and applications of the perchloric acid test for β-indolyl acetic acid and of the went pea test

The detection and determination of auxins in organic manures. Part II.—Extraction of auxins from manures, and applications of the perchloric acid test for β-indolyl acetic acid and of the went pea test

The detection and estimation of auxins in organic manures. Part I.—β-indolyl acetic acid or hetero-auxin. β-Indolyl propionic acid and β-indolyl butyric acid

The detection and estimation of auxins in organic manures. Part I.—β-indolyl acetic acid or hetero-auxin. β-Indolyl propionic acid and β-indolyl butyric acid

ON THE PLANT GROWTH HORMONE PRODUCED BY RHIZOPUS SUINUS

Since it was first discovered that cell elongation in the Avena coleoptile is controlled by a hormone, our understanding of the nature and role of this substance has progressed considerably. Apart from the elucidation of its functions in promoting growth, tropisms, and other reactions of the plant, the chemical nature of the substance has been extensively studied. The active substance produced by cultures of the mold Rhizopus suinus was shown by Nielsen (1930) to be ether-soluble, and by Dolk and Thimann (1932) to be an unsaturated organic acid, decomposed by strong acids but not by alkalies, and readily inactivated by oxidation. Its dissociation constant, as measured by Dolk and Thimann, is 10^-4.75. Previously, Went (1928) had shown the molecular weight of the active substance in Avena coleoptiles to be about 376. The active substance in human urine was isolated by Kogl and Haagen-Smit (1931) and by Kogl, Haagen-Smit, and Erxleben (1933), and shown to be an acid, C17H28O(OH)COOH (auxin A), whose lactone is also active, while from malt these workers later isolated (1933) a ketohydroxy acid, C17H28O(OH)COOH (auxin B), which had the same activity per unit weight. On account of the rather small amount of substance available from Rhizopus cultures, and also since the bulk of the partially purified product was lost through spontaneous inactivation (see section, “Concluding stages”), the chemical investigation of the active substance, begun earlier, was dropped. However, the many experiments on purification which had meanwhile been carried out showed that the active substance from Rhizopus did not behave in quite the same way as that from urine. Recently, however, it was shown by Kogl, Erxleben, and Haagen-Smit (1934) that there is in urine a second active substance, identical with β-indolylacetic acid, and Kogl and Kostermans (1934) showed that the molecular weight of the substance produced by Aspergillus and by Rhizopus is that of β-indolylacetic acid rather than that of the C18 compounds. Since preparations from Rhixopus have been extensively used for physiological work, both in this laboratory and elsewhere, the exact nature of the active substance is of considerable interest. The present paper will give evidence that the active substance produced by Rhizopus suinus is in fact β-indolylacetic acid. Identification by the preparation of derivatives and by mixed melting points with the pure synthetic substance was not possible on account of the small amount of material available. Nevertheless, the evidence given below is fairly conclusive. The method of purification, since it differs to some extent from that adopted by Kogl and his coworkers, will also be outlined. Finally, it will be shown that some of the peculiar conditions previously found to be necessary for the production of this growth substance (Thimann and Dolk, 1933) find a simple explanation on this basis.