Growth-regulating Substances Research Articles

Modification of 2,4-Dichlorophenoxyacetic Acid Movement in Bean Petioles by Light

There have been several reports of light effects on the movement of growth-regulating substances in plants. Shen-Miller and Gordon (6) found that phototropically active blue light decreased the basipetal movement of IAA in Zea coleoptile sections. Similarly, Thornton and Thimann (7) observed that blue light induced a transient decrease in the basipetal movemenit of IAA in Avena coleoptile tissues, but that red and far-red llight were without effect. Naqvi and Gordon (5) found that white light significantly decreased the basipetal transport of IAA in Zea coleoptiles. During a class experiment at the University of East Anglia, England, Professor M. B. Wilkins found that light appeared to reduce the acropetal movement of radioactive 2,4-D in intact bean petioles. This investigation was undertaken to determine whether light affects the movement of 2,4-D in green petiole sections of Phaseolus multiflorus.

The Effect of Growth-regulating Substances and Light on Olive Callus Growthin vitro

The Effect of Growth-regulating Substances and Light on Olive Callus Growth<i>in vitro</i>

Some biological properties of proteins of the mouse submaxillary gland as revealed by growth of tissues on electrophoretic acrylamide gels

Direct explantation of tissues on to longitudinal slices of acrylamides gels, in which various proteins have been separated by electrophoresis, has enabled the identification of a number of growth-regulating substances from the mouse submaxillary gland. The properties of the Nerve Growth Factor have been determined using isolated neuroblasts: thrombin has been shown to be an effective mimic of NGF. A thymolytic factor, which destroys mature lymphoid cells of thymus and mesenteric lymph node has been demonstrated—it is suggested that this may be the substance responsible for runting induced in vivo by administration of crude submaxillary gland extracts. Another protein in this gland appears to promote differentiation of cells of the early chick neural tube. Finally the mesenchyme stimulating agent has been studied, and shown probably to be acid mucopolysaccharide: its action is mimicked by heparin.

Studies on Senescence-Delaying Substances Extracted FromBrassica Oleracea GemmiferaL.

SummaryThree substances showing senescence-delaying properties in a barley leaf-section test were detected in extracts from Brussels sprout buttons and a quantitative correlation was established between the concentration of one of these factors and the rate of senescence of sprouts of two different Brussels sprout varieties. Application of a mixture of the plant growth-regulating substances benzyladenine and I-naphthylacetic acid to freshly harvested sprouts delayed yellowing in both varieties but was much more effective when applied to sprouts of the variety which naturally senesced more rapidly. On the other hand, cotyledons and leaf-discs from young seedlings showed no varietal difference in the rate of senescence and no difference in response to the hormone treatment. Preharvest hormone application to the variety Jade Cross delayed yellowing of the harvested sprouts.

Tumor formation in Nicotiana: Auxin levels and auxin inhibitors in normal and tumor-prone genotypes

Auxin and auxin-inhibitors from acidic ether extracts of normal stem tissue of Nicotiana longiflora, N. debneyi-tabacum, their tumor producing F 1 hybrid and non-tumor and tumor-prone segregants were separated by thin-layer chromatography and measured by an Avena curvature test. A significantly higher amount of auxin, very likely IAA, was found in the F 1 hybrid and the tumor-prone segregants as compared to the non-tumor tissues. Inhibitory substances appeared at different Rf's but generally in low amounts. One inhibitor seems to be identical with the "inhibitor β". In general, the results indicate that higher levels of auxin are associated with tumor-prone tissues in the F 1 hybrid and the segregants of a later generation carrying an alien longiflora chromosome on a debneyi-tabacum background. The role of this growth-regulating substance as related to tumor formation in Nicotiana is discussed.

Effects of Nutrient Factors, Water-Supply, and Growth-Regulating Substances on the Vegetative Growth Pattern of Peas and their Relationship to the Node of First Flower

Effects of Nutrient Factors, Water-Supply, and Growth-Regulating Substances on the Vegetative Growth Pattern of Peas and their Relationship to the Node of First Flower

Nucleic acid biosynthesis in seed germination: influences of auxin and growth-regulating substances.

Nucleic acid biosynthesis in seed germination: influences of auxin and growth-regulating substances.

Frond Articulation in Species of Polypodiaceae and Davalliaceae

Abscission, the natural detachment of a plant organ, is being studied by physiologists (e.g., Addicott, 1964; Rubinstein and Leopold, 1964; Jacobs and Kirk, 1966) after many years of interest on the part of morphologists. As new facts are discovered about growth-regulating substances, the physiological mechanisms governing senescence are becoming increasingly apparent. All such mechanisms must be correlated with anatomical characteristics of the abscission zone, thus necessitating a thorough knowledge of the cell types and patterns in this region of the plant. Miihldorf (1925) summarized the work done in the lower groups and also referred to the comprehensive coverage given to the higher plants: Monocotyledons (Bretfeld, 1880; Fouilloy, 1899) and dicotyledons (Tison, 1900; Lee, 1911). There are, however, several gaps in the anatomical literature concerning abscission, and one noticeable omission is a thorough description of the disarticulation of the rachis from the rhizome in ferns. In one early work (Basecke, 1908) three categories were described: (1) The frond falls before clear abscission lines are formed; (2) Disarticulation occurs along a line of cells present from the youngest stages; and (3) The frond disarticulates along a separation layer formed during maturity. Pfeiffer (1928, p. 163) examined other groups in addition to the ferns and established twelve classes of abscission based on various combinations of three characteristics of the separation layer. These included cell morphology, time of differentiation, and physiological condition of the cells after disarticulation. Most ferns are placed in class I of this system, in which the separation layer is formed by obtuse parenchyma, is evident as

Chemistry of Naturally-Occurring Growth-Regulating Substances

Chemistry of Naturally-Occurring Growth-Regulating Substances

Effect of 2,4-dichlorophenoxyacetic acid on different metabolic types of bacteria

The effect of auxins (plant hormones) on microorganisms has been studied by several investigators. The bacteriostatic effects of 2,4-dichlorophenoxyacetic acid (2, 4-D), a growth-regulating substance, was first demonstrated by Stevenson and Mitchell (13) and by Lewis and Hammer (3). Dubos (1) observed that a number of synthetic, unsaturated, ring-containing acids including 2, 4-D, exerted bacteriostatic effects on certain microorganisms.

Effect of Plant Regulators on the Incorporation of Phosphorus-32 into the Alcohol-soluble Fractions of Pea Seedlings

THIS communication reports experiments which we have carried out to examine and to compare some of the relations of the quantitative changes that ensue in the alcohol-soluble phosphorus fractions of pea seedlings, which have been induced by the effect of uncoupling and growth-regulating substances. In the course of the experiments, the changes in pea seedlings, which were treated with uncoupling and growth-regulating compounds in vivo, were recorded by labelling the phosphorylatecl products with 32P-phosphate arid paper chromatography.

Effects of Growth-Regulating Substances on Inulin-Storing Plant Tissues

Effects of Growth-Regulating Substances on Inulin-Storing Plant Tissues

Chemical control of crop growth and development.

Growth-regulating substances and the following forms of plant growth regulation are very briefly reviewed: control of dormancy and germination, of rooting of cuttings, and of plant shape; stimulation of vegetative growth and development; induction of flowering and of male sterility; control of fruit setting and growth; fruit thinning; delay of abscission; and defoliation and desiccation.- D.M.L.S. (Abstract retrieved from CAB Abstracts by CABI’s permission)

A survey of recent Japanese research on dormancy in potato tubers

A review is given of recent Japanese research on the physiology and biochemistry of dormancy in the potato tuber. The influence of natural growth inhibiting and stimulating compounds on tuberization and sprouting is discussed. The ratio between these growth-regulating substances probably controls the shift in relative activity of different respiratory enzyme systems occurring on the termination of dormancy.

Sclereid Distribution in the Leaves of Pseudotsuga Under Natural and Experimental Conditions

Al-talib, Khalil H., and John G. Torrey. (U. California, Berkeley.) Sclereid distribution in the leaves of Pseudotsuga under natural and experimental conditions. Amer. Jour. Bot. 48(1): 71–79. Illus. 1961.—A study of the distribution of sclereids in cleared leaves taken from 1-, 2-, and 4-year-old shoots of an adult tree of Pseudotsuga menziesii (Mirb.) Franco showed a repeated pattern of sclereid distribution along the shoot axis with many sclereids in the basal leaves grading into few or no sclereids in the terminal leaves of each year's growth. Attempts were made to influence sclereid distribution by bud defoliation of attached branches with and without auxin treatment and by testing the effects of growth-regulating substances on sclereid formation in leaves of excised buds of Pseudotsuga cultured in vitro. Whereas removal of the basal ¾ of the leaves at the time of bud unfolding had no effect on bud, leaf or sclereid development, removal of the leaves of the upper half or complete defoliation led to premature expansion of next year's terminal bud with leaves developing in part from presumptive bud-scale primordia. Indoleacetic acid at 0.5% in lanolin paste applied to the defoliated region prevented this premature bud expansion. Defoliation of the basal half did not affect sclereid formation in the terminal leaves. Sclereid development in leaves of prematurely expanded buds on defoliated branches was normal except in the few cases where bud expansion occurred in the presence of low-auxin concentrations. Then, sclereid development was inhibited. Sclereid formation in leaves of excised buds grown in nutrient culture was generally much less frequent than in intact branches, and auxin treatment still further reduced the frequency of sclereids. It was concluded that sclereid initiation and differentiation in the intact plant may well be under the control of hormonal factors in the plant, one of which may be auxin.

Effect of presoaking seeds in phytohormonal solution on the growth and yield of crops

The effects of presoaking the seeds of cereals like paddy (Oryza sativa) and cholam (Sorghum spp.), in nutrient salt solutions have already been reported (1958). Subsequently further experiments were carried out to study the effect of presoaking seeds of paddy (Oryza sativa) and ragi (Eleusine coracana) in growth-regulating substances like L-naphthaleneacetic acid (L-NAA) and B-indolylacetic acid (B-IAA) on the growth and yields, and the results are summarised in the following paragraphs.

Effects of Growth-regulating Substances on the Carbon Dioxide Evolution and Post-harvest Ripening of Tomatoes.

Effects of Growth-regulating Substances on the Carbon Dioxide Evolution and Post-harvest Ripening of Tomatoes.

Interaction of growth-regulating chemicals and tumefacient virus on plant cells

Lee (1955) demonstrated that microscopic tumor initials occur in the phloem fiber tissues of young stems of sweet clover infected with wound-tumor virus and that most of these never develop so that they produce macroscopic growths. Alpha-naphaleneacetic acid (NAA) and certain other growth-regulating substances act synergistically with this virus to stimulate the growth of such tumor initials and also to initiate the formation of many additional ones. The augmentation of tumor growth can be observed histologically within 72 hours after the application of 2% NAA in lanolin to the apical nodes of infected plants. The resulting tumorous growth is intermingled with many abortive adventitious roots in contrast to tumors which develop naturally as a result of infection with wound-tumor virus and which contain no adventitious roots.

Studies on Weed control by Herbicides: Observations on the phytocidal action of chemical herbicides on some weeds in Madras State

That growth-regulating substances have found wide use in the field of agriculture as weedkillers in recent years, revolutionising the method of eradication of weeds is too well known to need emphasis. Among the synthetic hormones, derivatives of phenoxyacetic acid such as 2, 4-D (2, 4-Dichloro-phenoxy acetic acid), MCPA (2-methyl 4-chloro phenoxyacetic acid) and 2,4,5-T (2,4,5-Trichloro phenoxy acetic acid) have proved to be the most effective. Commercial preparations of these are available in various forms such as acids, mineral salts, organic salts or amines and esters under different trade names. Against broad-leaved weeds 2, 4-D and MCPA are the most commonly used hormone weedicides. There is no great difference between these two chemicals in their biological activity. 2, 4, 5-T is also closely allied to 2, 4-D and has been found very effective in killing shrubby weeds and woody plants. It finds use also as an arboricide for killing trees and tree stumps.

A New Type of Plant Growth-regulating Substances

IN the course of systematic investigations of the dithiocarbamates, the compound S-(carboxymethyl)-dimethyldithiocarbamate, obtained by the reaction of sodium dimethyldithio-carbamate with monochloroacetic acid, was found to exhibit distinct plant growth-regulating activity. Tomato plants, about 20 cm. high, from which the tip was replaced by a glass tube containing a 1,000 p.p.m. solution of this compound showed very clear epinastic curvature and leaf deformations (Fig. 1) which were of the same type as those caused by 2,4-dichlorophenoxyacetic acid.