Synthetic Growth Regulators Research Articles

Effect of juvenile hormone on cirriped metamorphosis

The synthetic insect growth regulator, ZR-512 (2), causes precocious metamorphosis of the cyprid larva of the ãcorn barnacle, Balanus galeatus . Juvenile hormone (JH) (1) was also found to be effective in this assay at a threshold̃ concentration of 10 3 ppb, three orders of magnitude less active than ZR-512. Pretreatment of cyprids with certain subthreshold concentrations of JH partially inhibited the expected metamorphic activity of subsequently added ZR-512, suggesting that the two compounds interact with the same receptor.

Metabolism of the synthetic growth regulator α-chloro-β-(3-chloro-o-tolyl) propionitrile by mung bean seedlings

Summary Uptake and metabolism of the synthetic auxin α -chloro- β -(3-chloro-o-tolyl)propionitrile (Cl-ClTPN) were studied in intact Mung bean seedlings and in hypocotyl segments. Cl-ClTPN was taken up much faster by hypocotyl segments than by roots of intact plants. In extracts of plants treated with Cl-ClTPN several metabolites were detected: α -chloro- β -(3-chloro-o-tolyl)propionic acid, α -hydroxy- β -(3-chloro-o-tolyl)propionitrile and α -(3-chloro-o-tolyl)acetic acid (ClTAA). Besides, a lot of unidentified metabolites, most of them being apolar, could be revealed. From the identified metabolites and from the growth promoting activity of several homologues of them in the Avena cylinder test, it is suggested that Cl-ClTPN is converted to ClTAA, which is supposed to be the physiological active form of Cl-ClTPN.

An assessment of the value of plant growth regulators and herbicides for crops grown for the processed food industries

AbstractThe use of growth regulators to induce specific modifications in the growth of crops produced for processing is discussed. Increases in yield may be obtained by some treatments but more important effects on uniformity, quality, ease of harvesting and short‐term storage may also be achieved. The results of experiments on stem extension of calabrese, chemical stopping and defoliation of Brussels sprouts, root/shoot ratio modification of root crops and short‐term storage of green vegetables are presented. It is concluded that although so far, few commercial applications have been discovered, the requirements for growth regulation justify the search for new, more reliable synthetic growth regulators by improving screening tests and more efficient field trials. The use of herbicides on crops grown for processing is also discussed briefly and it is concluded that the prime requirement is for more efficient post‐emergence herbicides.

The Influence of the Synthetic Growth Regulator α‐Chloro‐(β‐(3‐chloro‐o‐tolyl) propionitrile on Some Phytochrome‐mediated Processes

AbstractIn intact Sinapis alba seedlings the synthetic growth regulator α‐chloro‐β‐(3‐chloro‐o‐tolyl)propionitrile (PRB‐8) inhibits the phytochrome‐mediated anthocyanin synthesis, carotenoid synthesis and L‐phenylalanine ammonia‐lyase activity. This action was compared with that of other auxins and with that of α‐chloro‐β‐(3‐chloro‐o‐tolyl)propionitrile‐homologues. From the results it appeared that PRB‐8 and some other o‐tolyl derivatives are more inhibitive than other known auxins.

The control of solute movement into sieve elements

AbstractA review is given of work on the movement of solutes into sieve elements, particularly with regard to investigations in which sieve tube exudate is obtained via the severed stylets of the aphid Tuberolachnus salignus (Gmelin), sited on bark strips or stem segments of willow.Evidence is given showing that the uptake of naturally occurring solutes is an active and highly selective process, thus the rate of uptake is governed not by differences in concentration between the sieve tube and the source cells, but by “potential” gradients. It is pointed out that the phenomenon of selectivity by the sieve tube cannot yet be explained, though experiments are described which indicate the site of selection to be the tonoplast of the source cells, at least in the case of sugars.Calcium is generally considered to be a rather phloem‐immobile cation. Evidence is given which demonstrates that a factor determining the immobility of this substance may be its inability to enter the sieve elements.Some data are provided on the movement of certain synthetic growth regulators and herbicides into the sieve elements of willow. These were found to be loaded within a short time from their application to the cambial surface of bark strip. It is suggested that their ability to move into sieve elements is brought about by competition with naturally occurring solutes.The conclusion is reached that investigations on solute loading are probably of more practical importance than those on the mechanism of longitudinal transport, since the control of the overall rate of transport may be in the former, rather than the latter, process.

A Comparison of Synthetic Growth Regulators with Indoleacetic Acid, with Respect to Methionine Metabolism

A Comparison of Synthetic Growth Regulators with Indoleacetic Acid, with Respect to Methionine Metabolism

MOVEMENT OF GROWTH REGULATORS IN PLANTS

SummaryThe movement of radioactivity added in the form of indoleacetic acid (as the natural hormone) or as 2,4‐dichlorophenoxyacetic acid (as a synthetic growth regulator) was followed in segments cut from petioles of Phaseolus vulgaris.The movement of 14C added as IAA was strongly basipetally polar, although significant amounts moved acropetally during 24 hours. The velocity of basipetal movement was 6 mm/hour for IAA‐[14C], and was the same for donor concentrations of 5 or 50 μM. The flux increased with increasing concentration in the donor blocks, but a progressively smaller percentage of the applied radioactivity was transported.2,4‐D‐[14C] was found to have very similar transport properties to those of IAA‐[14C], except that its velocity of basipetal movement was much less, namely 1 mm/hour. After correction had been made for the much slower net loss of 2,4‐D from its donor blocks, the acropetal movement of the 14C from the two substances was essentially the same.

The Effects of Growth Regulators on the Geotropism of Leaf Sheath Basal Region in Wheat Plant

SUMMARY The present study was carried out to ascertain the influence of growth regulating substances on the intercalary growth region of the wheat leaf sheath. Stem segments containing a node were used. The growth-stimulating substances, IBA, NAA, and 2:4-D, and the growth inhibiting substances, TIBA and DCA, were mutually antagonistic in their actions on the growth of this region. From the result of histological observation, it was indicated that the growth-stimulating substances promoted the cell elongation of this region and the growth-inhibiting substances inhibited it. Con sequently, it was indicated that the negative geotropism of the leaf-sheath basal region in the wheat plant was controlled by synthetic growth regulators. The geotropism of this region had no direct relation with the node and the internode, moreover it was found that there was no dorsiventrality in this region.

The Effects of Synthetic Growth-regulator Treatments on the Levels of Free Endogenous Growth-substances in Plants

The Effects of Synthetic Growth-regulator Treatments on the Levels of Free Endogenous Growth-substances in Plants

The Uses of Plant Growth Substances

Few developments in applied biology have been of such immense benefit to the farming world as those arising from the study of plant growth substances. A hundred million acres of clean crops bear annual witness to their value and popularity as selective weed-killers, and it is appropriate that Dr. Templeman, who discovered the first of these, should review the uses that have so far been found for the synthetic growth regulators.

THE INFLUENCE OF pH ON THE PHYTOTOXICITY OF 2:4‐DICHLOROPHENOXYACETIC ACID TO LEMNA MINOR

In recent years conflicting conclusions have been reached as to the effects of dissociation on the activity of growth-regulating substances. Lundegardh (I949) has concluded from his studies of wheat roots that both for the natural auxin in the root surface and for 3-indolylacetic acid the anions are the active agents in the process of cell elongation. In direct contrast, several groups of workers, in particular van Overbeek, Blondeau & Horne (I95i), have postulated for indolylacetic acid and synthetic growth regulators, such as 2: 4-dichlorophenoxyacetic acid, that only the undissociated molecule is active in bringing about an increased extension growth of pea tissue or curvature in the hypocotyl. On the other hand, Burstrom (I95i) holds that, while the increased extension growth of roots induced by oc-(phenoxy)isobutyric acid is largely determined by the concentration of acid anions, the inhibition of growth at higher and more directly toxic concentrations is probably dependent on the level of undissociated molecules. Simon & Blackman (I949) and Simon & Beevers (I952) have established for a wide range of biologically active weak acids that, as the pH of the external solution containing the active compound is reduced towards the pK value, so the concentration required to produce a given response falls according to a standard pattern. They have also demonstrated that this increase in biological activity with decreasing pH cannot be wholly accounted for in terms of the changing concentration of whole molecules, but must in part be ascribed to the dissociated ions. Simon, Roberts & Blackman (I952) found that with nitrophenols the influence of pH was maximal when the cells of either microorganisms or higher plants were in close contact with a relatively large volume of the solution containing the toxic compound. Thus when Lemna minor was grown in a culture solution containing 3: 5-dinitro-o-cresol the toxicity increased as the pH was reduced from 6-8 to 54 Blackman (I952) has emphasized that the influence of a given factor on the biological response of an active compound can be assessed with the greatest precision, when the concentration required to produce a standard effect is determined at different levels. In the previously published results linking pH with the activity of synthetic growth regulators, data of this type have either not been obtained or the results have not been examined in this way. It is partly for these reasons that the present experiments on L. minor were undertaken.

Selective phytotoxicity of synthetic growth regulators in wheat, oats and barley.

Selective phytotoxicity of synthetic growth regulators in wheat, oats and barley.

OVULE ABORTION IN TRADESCANTIA AS AFFECTED BY AQUEOUS SOLUTIONS OF 2,4–DICHLOROPHENOXYACETIC ACID

OVULE ABORTION IN TRADESCANTIA AS AFFECTED BY AQUEOUS SOLUTIONS OF 2,4–DICHLOROPHENOXYACETIC ACID

INFLUENCE OF SOME GROWTH‐REGULATING SUBSTANCES ON SUNFLOWER AND TOBACCO TISSUE IN VITRO

THE WELL-KNOWN responses of plant materials to various growth regulators have suggested a study of their effects on plant tissues as they were grown in vitro. This is a part of a larger work on fundamental aspects of pathological growth, in which mu%h attention has been given to the crown-gall disease caused by Phytomonas tumefaciens (Smith and Town.) Bergey et al. The early literature was reviewed by Riker and Berge (1935) and by Riker, Spoerl and Gutsche (1946). These growth regulators may be among the critical factors in the balances resulting, respectively, in or pathological growth (Riker, 1942). Tissue cultures have advantages for certain work over studies with whole plants. For example: (1) Simple, callus-like tissue may be grown vegetatively in vitro for unlimited periods free from variations arising from pollination. (2) Since the nutrients consist only of known chemicals, the basal metabolism can be studied with relatively simple and controlled procedures. (3) Changes in both kind and character of cells may be induced under controlled conditions. (4) The tissues may be exposed a long time to a wide range in concentrations of materials, including cell-stimulating and inhibiting agents, while other factors are constant. (5) It is possible to determine how far the tissue develops by itself or is dependent on other parts of the plant. Growth regulators show their presence in whole plants, for example, by epinasty, formation of adventitious roots, inhibition of bud development, stimulation of cambial activity, and delayed abscission of old leaves. A number of natural and synthetic growth regulators may produce various ones of these effects and either stimulate or inhibit abnormal cell proliferation (reviewed by Grieve, 1943; van Overbeek, 1944; Thomson, 1945). The exact role they play in crown gall is not established. Large numbers of growth regulators have been tested on many kinds of whole or decapitated plants (Thompson, Swanson and Norman, 1946,; Zimmerman, 1942, 1943). The influence of certain growth regulators has already been tested on growth in vitro of normal plant tissue (reviewed by Nobecourt, 1943; Gautheret, 1945). Indole-3-acetic acid particularly was important for growth of plant tissue cultures from many species and was indispensable in some cases. Gautheret (1945) noted that indole-butyric acid and naphthalene-acetic acid 1Received for publication April 14, 1947. This work was supported in part by the Donner Foundation and by the Research Committee of the Graduate School from funds supplied by the Wisconsin Alumni Research Foundation. Published with the approval of the Director of the Wisconsin Agricultural Experiment Station. The authors are indebted to Eugene Herrling for preparing fig. 1-10. could be substituted for indole-3-acetic acid when indole-3-acetic acid was needed for tissue cultures. With some species these materials modified the shape and kind of cells in the cultures (Gautheret, 1945). However, the effects of these materials on pathological plant tissue growing in vitro have received only limited attention. Indole-3-acetic acid and alpha-naphthalene-acetic acid -prevented bud, leaf, and stem formation on tobacco callus in a liquid medium (Skoog, 1944). The present paper describes the influence of some representative natural and synthetic growth regulators on excised tissues in vitro. It aims to clarify the stimulating or inhibiting effects on growth of various substances, their critical concentrations, and whether they act alike on two different tissues. An abstract of some of this material has already appeared (Hildebrandt and Riker, 1946b). MATERIALS AND METHODS.-Tissue cultures from two species were used. The sunflower tissue was isolated from a secondary crown-gall on Helianthus annuus L. var. Giant Russian and was free of of the crown-gall bacteria. The tobacco tissue (P. R. White strain) was from the hybrid Nicotiana glauca Grah. 9 X N. langsdorffii Weinm. S. Both tissues have already been described and illustrated (Hildebrandt, Riker and Duggar, 1945). The cultural procedure was essentially as given by Hildebrandt, Riker and Duggar (1945). Four tissue pieces were grown in each 125 ml. Erlenmeyer flask on 50 ml. of a basal, mineral-salt, agar medium. The basal medium for the sunflower tissue has been described (Hildebrandt, Riker and Duggar, 1946a). A similar medium (Hildebrandt, 1944) for the tobacco tissue had the following ingredients in milligrams per liter of distilled water: 400 Na2SO4, 800 Ca(NO3)2 4H20, 180 MgSO4 7H20, 160 KNO3, 65 KCI, 33 NaH2PO4 H2O, 9 MnSO4 4H2O, 3 ZnSO4 7H2O, 3 H3BO3, 1 KI, 20 ferric tartarate, 3 glycine, and 0.1 thiamine hydrochloride. All these chemicals were of reagent grade except boric acid and potassium iodide. In addition each liter contained 20 g. of sucrose and 5 g. of Difco agar. The growth-regulating compounds used and their sources were as follows: cysteinehydrochloride, indole-3-acetic acid, indole-butyric acid, parachlorophenoxy-acetic acid, alpha-naphthalene-acetic acid, alpha-naphthalene-acetamide, and beta-naphthoxy-acetic acid (Eastman Kodak Company); 2,4dichlorophenoxy-acetic acid, and 2,4-dichlorophenoxy-butyric acid (Dow Chemical Company); and sodium 2,4-dichlorophenoxy-acetate (E. D. Whitman, Ohio State University). The sodium 2,4-dichlorophenoxy-acetate, indole3-acetic acid, and cysteine hydrochloride, respec-

THE INFLUENCE OF NUTRITION ON FUSARIUM BASAL ROT OF NARCISSUS AND ON FUSARIUM YELLOWS OF GLADIOLUS

THE MOST serious disease of narcissus on the East Coast of the United States is a basal rot of the bulbs caused by Fusarium oxysporum f. narcissi (Cke. et Mass.) Snyder and Hansen. Some rot may be evident at the time of digging but the majority of the bulbs appear to be sound even though many are infected. After 6 to 8 weeks in storage many of the infected bulbs become rotted, particularly if high temperature and moisture conditions prevail and the bulbs cure slowly after digging. The closely related species Fusarium oxysporum f. gladioli (Massey) Snyder and Hansen, causes one of the most serious diseases of gladiolus, yellows, or corm rot, which in recent years has been responsible for annual losses of as much as 60 per cent in the extensive Florida plantings. As a result of commercial advertising, bulb growers have recently become interested in the possibility of using growth-regulating substances to flower and bulb production and to control disease. Some manufacturers of synthetic hormones and purine compounds have recently advocated the use of their products on bulbs to increase and accelerate root production. An advertisement by one of these companies alsoadds that their material controls serious bulb and tuber rots. This material contains allantoin, one of the purines. Another material4 consisted largely of sucrose, uric acid, and naphthalene acetamide at the time our tests were made. A third material is a rather widely used proprietary fertilizer containing 60 to 800 mg. of a synthetic hormone, indolebutyric acid or naphthaleneacetic acid, per ton of fertilizer, in addition to nitrogen, phosphorus, and potassium, and a number of minor elements. Our investigations of fertilizer requirements of narcissus and gladiolus have shown that fertilizers, synthetic growth regulators, and the nitrogen bases markedly affect the severity of the Fusarium diseases of these crops. In narcissus, basal rot is increased greatly when certain of the synthetic growth regulators and nitrogen bases are used in dips and in powders on the bulbs. It was also found that these materials stimulate the growth of Fusarium oxysporum f. narcissi in culture and a short note was published to this effect (Stuart and McClellan, 1943). A more complete account of the investigations is reported in this paper. FIELD RESULTS WITH GROWTH REGULATORS AND NITROGEN BASES.-On September 21, 1940, King Alfred narcissus bulbs 12 to 14 cm. in circumference