Synthetic Growth Regulators Research Articles

Systematic analysis of glucoiridoids from Penstemon serrulatus Menz. by high-performance liquid chromatography with pre-column solid-phase extraction

Samples (122) of crude ethanol-extracts of callus tissues from Penstemon serrulatus Menz. were used to develope a solid-phase extraction (SPE) clean-up procedure using the octadecylsilica packed cartridge for removing a complex mixture of free phenolic acids and anthocyanine-like colour substances, for the isolation of a sufficiently clean glucoiridoid fraction (GF). An additional SPE sample pretreatment step of the crude extracts enabled the enhancement of selectivity and sensitivity on applied high-performance liquid chromatography (HPLC) for the identification and quantitation of the iridoid constituents of the GF fraction. In particular, the presence of five valeriana-type esterified glucoiridoids which consist of penstemide, serrulatoloside, 8-epi-valerosidate, 7-desoxy-8-epi-valerosidate and serrulatoside in prepared GF fractions were determined by isocratic HPLC measurements. During a single HPLC separation, the traces of four non-esterified glucoiridoids, i.e. harpagide, aucuboside, loganine and plantarenaloside, were satisfactorily resolved and detected on the registered HPLC chromatograms of investigated GF fractions. The HPLC analyses were carried out on an octadecylsilica column (25 × 0.4 cm I.D.) using methanol-water (30:7070, v/v) as the mobile phase with a flow-rate of 2 ml/min and the absorbance was monitored at 220 nm using an UV detector. The described chromatographic assay for penstemide, which exhibits potential antitumor activity against the P-388 lymphocytic leukemia cells, was applied to the monitoring and standardization of growth conditions for the callus cultures of P. serrulatus. Penstemide contents were found to range from 0.05% to 2.7% of the fresh weight of the investigated callus samples. Multivariate statistical methods (principal components analysis) was applied to demonstrate the influence of a variety of compositions of growth media (especially the type and concentration of synthetic growth regulators, e.g. 3-indolylacetic acid, 2,4-dichlorophenoxyacetic acid or 1-naphthylacetic acid, on the formation of different profiles of glucoiridoids in the callus cultures of P. serrulatus. Calculated principal component values were found to be useful for the explanation of variations in the penstemide/serrulatoloside ratio in the investigated samples and for determining the most favourable growth conditions in plants leading to optimal glucoiridoid biosynthesis.

Thidiazuron-Induced Somatic Embryogenesis Enhances Viability of Hydrogel-Encapsulated Somatic Embryos of Geranium

Summary Somatic embryos of geranium (Pelargonium x hortorum Bailey cv. Scarlet Orbit Improved) were hydrogel-encapsulated using 3 % sodium alginate and 50 mM calcium chloride. The resultant synthetic seed germinated normally and produced flowering plants within twelve to fourteen weeks. The synthetic growth regulator thidiazuron was superior to indoleacetic acid and benzylaminopurine for producing somatic embryos that confer viability to synthetic seeds following storage at 4 °C for 45 d.

Effects of plant growth regulators on acetylene-reducing associations between Azospirillum brasilense and wheat

Treatment of wheat seedlings with the synthetic auxin, 2,4-dichlorophenoxyacetic acid (2,4-d), induced nodule-like structures or tumours (termed para-nodules) where lateral roots would normally emerge. The formation of these structures promoted increased rates of acetylene reduction at reduced oxygen pressure (0.02–0.04 atm) in seedling inoculated with Azospirillum brasilense, compared to seedlings inoculated without auxin treatment. Fluorescent microscopy, laser scanning confocal microscopy and direct bacterial counts all showed that the 2,4-d treatment stimulated internal colonization of the root system with azospirilla, particularly in the basal region of the nodular structures. Both colonization with azospirilla and acetylene-reducing activity were further stimulated by simultaneous treatment with another synthetic auxin, naphthaleneacetic acid (NAA) and, less reliably, with indoleacetic acid (IAA) and indolebutyric acid (IBA). These auxins produced shortening of many initiated lateral roots, although 20 times the concentration of NAA was required to achieve rounded structures similar to those obtained with 2,4-d. Treatment with NAA, IAA or IBA alone also stimulated colonization with azospirilla and acetylene reduction rates at 0.02 atm oxygen, but less effectively than by treatment with 2,4-d. Such exogenous treatments of wheat seedlings with synthetic growth regulators provide an effective laboratory model for studies on the development of a N2-fixing system in cereals.

Effect of 1,2-benzisoxazole-3-acetic acid on plant regeneration from protoplasts of Nicotiana tabacum

Benzisoxazole-3-acetic acid, a new synthetic growth regulator, was administered to protoplast cultures from Nicotiana tabacum and subsequently to the developed microcalluses, to test its activity on plant regeneration from protoplasts in different culture conditions. Such activity, compared to that of naphthalene-acetic acid, proved to be rather low in the stage of cellular division and microcallus formation but particulary high in the stage of shoot induction from microcallus, thus confirming that the activity of this compound is mainly morphogenetic.

Validation of an enzyme immunoassay for analysis of methoprene residues on tobacco

Methoprene [isopropyl 11-methoxy-3,7,11-trimethyl-2(E),4(E)-dodecadienoate] is a synthetic insect growth regulator that is used extensively for control of the cigarette beetle(Lasioderma serricorne) in stored grins and tobacco products. In 1990 a successful cELISA was developed for methoprene; more recently, this immunoassay was redeveloped as an enzyme immunoassay (EIA). In the present study, HPLC data were used to test the accuracy and precision of the assay for use with various tobacco genotypes

Effects of some natural and synthetic growth regulators on sex-expression of Myrica esculenta Buch-Ham. ex D. Don

Gibberellic acid (GA,), chlorflurenol and ethrel were applied at different concentrations to either male or female trees of Myrica esculenta. GA3 induced intersexual flowers both on the male and female trees whereas chlorflurenol and ethrel induced similar (intersexual) flowers but only on the male plants. When GA3 was applied in combination with chlorflurenol, fewer intersexual inflorescences appeared on the male plants along with a significant decline in the number of flowers per inflorescence. In combination, chlorflurenol and ethrel induced copious female and intersexual inflorescences per male plant, especially when two successive treatments of 100 mg/I of chlorflurenol and 1920 mg/l of ethrel were applied. The induced female inflorescences later bore fruits.

Accelerating Fraser Fir Seedling Growth with Benzylaminopurine Sprays

Foliar application of the synthetic growth regulator BA was evaluated for increasing the duration and extent of Fraser fir [Abies fraseri (Pursh.) Poir.] seedling growth. Aqueous solutions of 0, 222, or 444 μm BA (0, 50, or 100 ppm) were sprayed on the shoots of Fraser fir seedlings biweekly from 18 until 38 weeks after planting. Foliar sprays of 444 μm BA increased seedling height 19%, increased shoot weight 57%, reduced root weight 22%, and increased total weight 27%. Apical meristem activity was stimulated and the long periods of dormancy typical of Fraser fir seedlings were avoided. Chemical name used: 6-benzylaminopurine (BA).

PLANT GROWTH AND DEVELOPMENT IN MOLECULAR PERSPECTIVE

PLANT GROWTH AND DEVELOPMENT IN MOLECULAR PERSPECTIVE

Bioregulator enhancement of sink activity in sugar beet

The sink mobilizing abillity is partially determined by sugar uptake rates of storage cells. Two synthetic growth regulators (Pix and BAS 106W) were tested for their effect on sucrose uptake in root tissue discs or glucose uptake in cell cultures of sugar beet. In tissue discs, uptake at the plasmalemma was determined by incubating the discs for 1 h in the presence of 5 mM sucrose and at the tonoplast for 4 h in the presence of 40 mM sucrose. Cell cultures were incubated for 1 h in the presence of 1 mM glucose. Pix (10 mg l−1) caused a 20% stimulation of active sucrose uptake at the plasmalemma. Active sucrose uptake at the tonoplast was increased 67% by 100 mg l−1 Pix. No effect of BAS 106W was observed on sucrose uptake in tissue discs. In cell cultures, a 65% enhancement of active glucose uptake was observed with both Pix and BAs 106W. When the bioregulators were applied to the root medium of seedlings, Pix but not BAS 106W resulted in increased root/shoot ratio, translocation of 14C-assimilates, and allocation of more biomass to the root sink. The data suggested that sugar transport and translocation may be used as biochemical criteria for rapid screening of effective yield enhancing bioregulators.

Biochemistry of a plant dormancy process: Prospects for chemical regulation

The mobilization of protein nitrogen reserves in apple shoot bark is subject to abscisic acid (ABA)-mediated regulation. At the biochemical level proteolytic activities in the shoot bark are suppressed in the autumn. As endogenous ABA levels decline during the autumn and winter tissue protease levels increase in parallel with the rate of inducible breakdown of reserve protein; metabolic demandper se plays no significant role. This process is used as a model system to explore the possibilities for chemical regulation (”bioregulation“) of ABA-determined dormancy phenomena by: manipulation of tissue ABA concentrations, substitution of synthetic growth regulators and direct interference at the site of action.

Water Relations in Young Growing Wheat Leaves after Application of (2-Chloroethyl)trimethyl- ammoniumchloride (CCC) to the Roots of Wheat Seedlings

Abstract The influence on the water relations of the third developing leaf of (2-chloroethyl)trimethylammoniumchloride, a synthetic growth regulator, applied to the roots of young wheat plants (Triticum aestivum L.) has been investigated. The tissue water potential and the pressure potential were found to be reduced by several bars in comparison to the untreated controls, whereas the osmotic potential remained unchanged. The content of soluble reducing sugars was considerably increased in the cell sap of CCC-treated leaves. With this accumulation, however, the turgor was not maintained. Additionally, CCC-treated leaves showed considerably lower transpiration rates and higher diffusive resistance than the controls. Thus, the application of CCC to the roots causes alterations in the water relations of developing wheat leaves, which resemble those induced by water deficiency.

Antagonistic interaction between auxins and the growth regulator NC 9634

The synthetic growth regulator NC 9634, [(3-phenyl-1,2,4-thiadiazol-5-yl)thio] acetic acid (NC 9634) was shown to have anti-auxin properties in bioassay tests. The inhibition of wheat coleoptile extension growth by concentrations of NC9634 up to 260 μM was completely overcome by 60 μM IAA, 50 μM NAA or 50 μM 2,4-D. In cress root tests 2.6 × 10−7M NC 9634 stimulated root elongation and relieved the growth inhibiting effect of 2,4-D. Extension growth of intact apple shoots was inhibited by NAA, which proved lethal at concentrations above 6.25 × 10−4M. NC 9634 applied in combination with the NAA, reduced this growth inhibiting effect and prevented death of shoots sprayed with high auxin concentrations.

Chlorflurenol-methyl in soil: degradation, leaching, and effects on microbiological processes.

Tests were conducted with the synthetic growth regulator chlorflurenol-methyl to investigate its rate of degradation in soil, leaching behavior, and possible side-effects on the soil microflora and on soil physiological processes. With two sandy soils (Ct = 1.0 and 2.58%) which were treated with 11.35 mg kg-1 chlorflurenol-methyl (congruent to 2.8 kg a.i. ha-1), over 90% of the compound disappeared within 4 to 8 days. The degradation products were 2-chloro-9-hydroxyfluorene-9-carboxylic acid and 2-chlorofluorenone, which undergo further decomposition. In leaching tests with three sandy soils (Ct = 0.69, 1.0 and 2.58%), chlorflurenol-methyl was not washed from the soil; however, with one soil (0.69% C), very small residues were observed in the effluent identified as 2-chlorofluorenone. In side-effects experiments with a parabrown (Ct = 1.26%) and a chernozem soil (Ct = 2.3%), which were treated with 1 and 10 mg kg-1 chlorflurenolmethyl, no persistent inhibition of anaerobic or aerobic nitrogen fixation (C2H2-reduction) was detected. Ammonification, nitrification, and mineralization of soluble starch were also not influenced. The mineralization of cellulose in compost soil (Ct = 13.59%) was temporarily delayed; however, this delay was later compensated for by a higher mineralization rate. The colonization density of fungi on soil particles and the numbers of bacteria, actinomycetes, and fungi were not negatively influenced. Chlorflurenol-methyl does not significantly influence these microbiological processes and populations in the soil.

Synthetic Growth Regulators: Potential for Development

Agricultural uses of plant growth regulators and plant hormones are probably more numerous and diverse than commonly realized This area of agricultural chemistry has a long history, and it contributed to the development of selective, organic herbicides which are important in agriculture today While a few applications of growth regulators to major field crops have been developed, most of the uses are for specialty, high-value, low-acreage crops Most of the current plant growth regulator uses involve modification of development rather than changes in basic productivity Most are growth inhibitors rather than growth promoters Crop yields are often increased indirectly by preventing losses, hastening the production cycle, or facilitating mechanical harvest operations. In a few crops, growth regulators actually increase plant growth or divert photosynthate to the harvested product so that the actual productivity is increased There are a variety of reasons to anticipate a significant increase in the commercial use of growth regulators and many approaches to discovering and developing these new uses Models for promoting growth regulator technology include analysis of individual crops to select specific goals, analysis of hormonal roles and physiology to identify opportunities, and improvements in the empirical testing approach. Examples for the models are the crop, cotton, and the hormone regulator, ethylene The lag in the development of growth regulators behind that of other types of agricultural chemicals is both natural and fortuitous Until major yield-limiting requirements and pests were under some degree of managerial control, the advantage of being able to manipulate growth and development chemically was marginal In addition, now that agriculturists are trying to minimize the use of pesticides and fossil fuels, growth regulator technology can be developed in harmony with these important goals Growth regulators appear to have a growing role in integrated pest management which would then appear to be part of a larger system of integrated plant growth management

Ethylene evolution by thrips-infested cowpea provides a basis for thrips resistance screening with ethephon sprays

Pests are major constraints to increased cowpea production in tropical subsistence agriculture where cash inputs are small. Breeding for pest resistance is therefore the major component of pest management strategies for crop improvement. Of paramount economic importance among these pests are flower thrips [Megalurothrips sjostedti (Tryb.)] which may cause abscission of flower buds, flowers and peduncles, leading to seed yield losses of up to 100% (refs 1, 2). It has been difficult to use available sources of moderate thrips resistance in a breeding programme because of thrips variation in time and space in field screening3. This paper reports that ethylene is produced when thrips infest cowpea peduncles. We have used this fact to develop a screening technique using the synthetic growth regulator ethephon (2-chloroethylphosphonic acid), which when sprayed on the plant is translocated to actively-growing tissue, where it breaks down to form ethylene4–6. Cultivars susceptible to abscission caused by thrips also show increased abscission with ethephon treatment. The technique may be useful in identifying sources of resistance to other abscission-causing agents.

The effects of Z(3-phenyl-1,2,4,4-thiadiazol-5-yl)thio] acetic acid, a synthetic growth regulator, on auxin uptake by tobacco stem segments and crown gall suspension culture cells

Z(3-phenyl-1,2,4-thiadiazol-5-yl)thio] Acetic acid (PTAA) is a novel synthetic plant growth regulator causing disturbance of trophic responses and increased branching in one-year-old apple trees and a variety of other species. Its effects are similar to those of 2,3,5-triiodobenzoic acid (TIBA), an inhibitor of popular auxin transport. Auxin uptake by both tobacco stem segments and Parthenocissus tricuspidata crown gall tissue culture cells is stimulated 2–3 fold by both PTAA and TIBA, probably as a result of inhibition of a component of auxin efflux from the cells. The optimum concentration of PTAA is 0.5–10 μ mol/l at pH 4.5 and 10–100 μ mol/l at pH 6.5 for the crown gall cells and about 10 μ mol/l at Ph 6.0 for tobacco stem tissue. It is suggested that PTAA may be an inhibitor of polar auxin transport. Such inhibition may partly account for its growth-modifying properties.

Growth regulation in vegetable crops

Vegetables are more important as a world food source than consideration solely of the area under cultivation would imply. Yet, although they are generally high-value crops the variety of plant species and cultural conditions embraced limits each one's economic potential for the use of new synthetic growth regulators. Compounds which already have application in a major crop, however, can be used in vegetables to improve germination, crop uniformity, ease of harvesting and storage.

TESTS OF A GROWTH REGULATOR ON MOSQUITOES (DIPTERA: CULICIDAE) AT CHALK RIVER

Tests of a synthetic insect growth regulator (Altosid SR-10, or Methoprene, Zoecon Corp., Palo Alto, Calif.) have been completed recently at Chalk River Nuclear Laboratories. This paper reports on the effectiveness of this promising material in tests on several species of mosquitoes of this area. The low toxicity to mammals, the relative absence of deleterious effects on non-target aquatic organisms under normal use (Staal 1975), the fact that Altosid is readily biodegradable and is effective at low rates of application would recommend this material for the control of mosquito larvae. Reports in the literature on the use of juvenile hormone-type compounds have dealt mainly with mosquitoes in the southern United States; for example, Schaefer and Wilder (1973) reported on Aedes nigromaculis, A. melanimon, and Culex tarsalis in California. In our tests, we wished to determine its effectiveness on local species and in mosquito breeding pools where temperatures would be lower than in the work mentioned above.

Effects of the Synthetic Insect Growth Regulators Methoprene and Hydroprene on Survival, Development or Reproduction of Six Species of Stored-products Insects12

Six species of stored-products insects were reared on diets treated with methoprene and hydroprene at 1, 5, 10, and 20 ppm. Both compounds at 20 ppm prevented emergence of pupae of Tribolium castaneum (Herbst) and substantially reduced it in T. confusum Jacquelin duVal. At 5 ppm or higher, they inhibited oviposition in both species. Larvae that failed to pupate in treated food continued to molt, and those that survived to 120 days or longer after emergence were larger than normal larvae. Methoprene at one ppm or higher prevented emergence of adults of Oryzaephilus mercator (Fauvel), and O. surinamensis (L.) in treated rolled oats or cornmeal. Hydroprene produced a similar effect in cornmeal treated at 5 ppm or higher. Both compounds caused morphogenetic malformities in flour beetles and grain beetles. None of the pupal-adult intermediates or malformed adults survived. Hydroprene at 10 and 20 ppm in wheat almost completely inhibited progeny production by Sitophilus granarius (L.). Both compounds caused decreasing productivity with increasing concentration in S. oryzae (L.) but not enough to provide useful control.

On the Requirement of a Hydroxynitrile Lyase in the Conversion of Orthonil to Chloro-Tolylacetic Acid

Summary The conversion of the synthetic growth regulator α-chloro-β(3-chloro-o-tolyl)propionitrile (CI-CITPN) into α-(3-chloro-o-tolyl)acetic acid (CITAA) was studied at an enzymic level. Cell-free extracts of mung bean seedlings convert very well the metabolite α-hydroxy-β-(3-chloro-o-tolyl)-propionitrile into CITAA. When the enzyme synthesis is blocked by a pre-incubation in p-fluorophenylalanine, CITAA seems to be the sole chloro-tolyl derivative that can induce a growth stimulation. Growth tests, immediately after the application of auxins, gives further evidence that CITAA is the active chloro-tolyl auxin. From the results mentioned it further follows that no enzyme induction is needed. The interaction of vaniline-cyanohydrine in different growth tests indicates the interaction of a hydroxynitrile lyase (already endogeneous present), that catalizes the formation of the effective auxin CITAA from the exogeneously applied CI-CITPN.