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PubMed1970

Abnormal Stomatal Behavior and Hormonal Imbalance in flacca, a Wilty Mutant of Tomato: I. Root Effect and Kinetin-like Activity.

The wilty tomato mutant, flacca, and the normal variety, Rheinlands Ruhm, were compared for kinetin-like activity in ontogeny. The mutant wilts easily because its stomata resist closure. This stomatal resistance decreases with age. The occurrence of a root factor which induces stomatal opening was inferred from grafting experiments. It was hypothesized that the excessive stomatal openings in the mutant may result from excess of kinetin-like activity in the leaf of that plant. In addition, it was suggested that the closure of stomata in the aging mutant is due to a decrease of kinetin-like activity with age. Kinetin-like activity in the leaf was determined by incorporation of labeled leucine. The concentration of cytokinins in root exudate and leaf extract was determined by the soybean callus assay. Evidence was presented of higher kinetin-like activity in the leaves of the mutant and higher cytokinin concentration in its root exudate. Cytokinin concentration in the shoot was found to be only slightly higher in the mutant than in the normal plants. Kinetin-like activity in the leaf and cytokinin concentration of root exudate decreased with age in both mutant and normal plants. Kinetin-like activity in the leaves of mutant plants, which phenocopy the normal variety as a result of continuous application of abscisic acid, was lower than in control mutant plants. The significance of these findings per se and in connection with stomatal behavior is discussed.

Journal Article↗
PubMed1999

N(6)-Furfuryladenine, kinetin, protects against Fenton reaction-mediated oxidative damage to DNA.

N(6)-Furfuryladenine (kinetin) has been shown to have anti-ageing effects on several different systems including plants, human cells in culture, and fruitflies. Since most of the experimental data point toward kinetin acting as an antioxidant both in vitro and in vivo, and since much evidence supporting a causal role of oxidative damage in ageing is accumulating, we tested the antioxidant properties of kinetin directly. Using 8-oxo-2'deoxyguanosine (8-oxo-dG) in calf thymus DNA as a marker for oxidative damage, we demonstrate that kinetin significantly (P < 0.005) protects the DNA against oxidative damage mediated by the Fenton reaction. Kinetin inhibited 8-oxo-dG formation in a dose-dependent manner with a maximum of 50% protection observed at 100 microM kinetin.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2005

Influence of arbuscular mycorrhizal fungi and kinetin on the response of mungbean plants to irrigation with seawater.

Increasing use of saline water in irrigation can markedly change the physical and chemical properties of soil. An experiment was carried out to investigate the interaction between the mycorrhizal fungus Glomus clarum, isolated from a saline soil, and kinetin on the growth and physiology of mungbean plants irrigated with different dilutions of seawater (0, 10, 20, and 30%). The growth, chlorophyll concentration and sugar content of mycorrhizal plants was greater than that of non-mycorrhizal plants under all conditions (with or without seawater). The dry weight of both mycorrhizal and non-mycorrhizal mungbean plants irrigated with 10% seawater was significantly increased by treatment with kinetin. The mycorrhizal symbiosis increased root:shoot dry weight ratio, concentrations of N, P, K, Ca and Mg, plant height, protein content, nitrogen or phosphorus-use efficiencies, and root nitrogenase, acid or alkaline phosphatase activities of seawater-irrigated mungbean plants, with little or no effect of kinetin. Kinetin treatment generally decreased chlorophyll concentration and sugar content in mycorrhizal plants as well as Na/N, Na/P Na/K, Na/Ca and Na/Mg ratios. Root colonization by G. clarum was increased by irrigation with seawater, and kinetin had no consistent effect on fungal development in roots. This study provides evidence that arbuscular mycorrhiza can be much more effective than kinetin applications in protecting mungbean plants against the detrimental effects of salt water.

Kinetin↗
PubMed1997

A mechanism for the in vivo formation of N6-furfuryladenine, kinetin, as a secondary oxidative damage product of DNA.

Recently, we have reported the presence of kinetin (N6-furfuryladenine) in commercially available DNA, in freshly extracted cellular DNA and in plant cell extracts. We have also found that kinetin has electrochemical properties which can be used for monitoring the level of this modified base in DNA. Here, for the first time, we propose a mechanism for the formation of kinetin in DNA in vivo, based on the analyses of its mass spectra. Since hydroxy radical oxidation at the carbon 5' of the deoxyribose residue yields furfural, we propose that this aldehyde reacts with the amino group of adenine and, after intramolecular rearrangement, kinetin is formed in vivo. Thus kinetin is the first stable secondary DNA damage product known to date with very well defined cytokinin and anti-aging properties, linked to oxidative processes in the cell. These results also indicate that N6-furfuryladenine or kinetin is an important component of a new salvage pathway of hydroxy radicals constituting a 'free radical sink'. In this way, the cells can neutralize the harmful properties of hydroxyl radical reaction products, such as furfural, and respond to oxidative stress by inducing defence mechanisms of maintenance and repair.

Adenine↗
PubMed1971

Action of kinetin on cotyledons of fenugreek.

Isolated cotyledons of fenugreek (Trigonella foenum graecum L.), which respond rapidly and specifically to the application of cytokinins with stimulated expansion, have been used to study the primary action of kinetin. Gross chemical analysis showed that ribonucleic acid increased within 24 hours in response to kinetin application. 8-Azaguanine inhibited both kinetin-induced expansion and RNA synthesis; 5-fluorodeoxyuridine inhibited only the RNA synthesis.Cotyledons produced nitrate reductase activity in response to 20 mm nitrate only in the presence of either light or kinetin and especially in the presence of both. Abscisic acid and inhibitors of RNA and protein synthesis depressed this response. Inhibitors affecting chloroplast development and function did not reduce the response in the presence of light and kinetin.In vitro incorporation of (14)C-l-leucine and (14)C-l-phenyl-alanine into protein by various recombinations of microsomal and 160,000g supernatant fractions varied according to the pretreatment which the cotyledons had received before the preparation of the fractions. Stimulatory effects were mainly associated with the microsomal fractions.The formation of leucine-, valine-, and tyrosine-tRNA complexes by high speed supernatant fractions from differently pretreated cotyledons was also compared. The sharp stimulation of the process by adding tRNA was found to be independent of the kind of preincubation that the cotyledons used for the tRNA extraction had received.It is concluded that the evidence is not in favor of kinetin correcting specific tRNA deficiencies. Kinetin removes a limitation that prevents the synthesis of RNA and genome expression.

Journal Article↗
PubMed1973

Mechanism of a Synergistic Effect of Kinetin on Auxin-induced Ethylene Production: Suppression of Auxin Conjugation.

In hypocotyl segments of mung bean (Phaseolus mungo L.) seedlings, exogenously supplied indoleacetic acid was rapidly conjugated mainly into indoleacetylaspartic acid, which was inactive in inducing ethylene production. Kinetin is known to stimulate indoleacetic acid-induced ethylene production. The mechanism of kinetin action on indoleacetic acid-induced ethylene production by hypocotyl segments of mung bean seedlings was studied in relation to indoleacetic acid uptake and indoleacetic acid metabolism. Kinetin enhanced indoleacetic acid uptake during the initial 2-hour incubation and markedly suppressed the conversion of indoleacetic acid to indoleacetic acid conjugates throughout the whole 7-hour incubation. As a result, there was more free indoleacetic acid and less conjugated indoleacetic acid in the segments treated with kinetin than in those receiving no kinetin. A close relationship was demonstrated between the rate of ethylene production and the level of free indoleacetic acid, which was regulated by kinetin.

Journal Article↗
PubMed1976

Effects of kinetin and root tip removal on exudation and potassium (rubidium) transport in roots of honey locust.

Exudation, (86)Rb transport, and water permeability were examined in excised roots of honey locust (Gleditsia triacanthos L.) treated by removing the tip 2 mm (tip-cut 2 mm) or tip 8 mm of the root, or by adding kinetin, or by both treatments. Tip removal increased the rate of exudation. Kinetin, 5 x 10(-6)m, inhibited exudation and Rb transport in tip-cut 2-mm roots; the inhibition was reversible. Kinetin inhibition of exudation was initially associated with lower K(Rb) transport and later with decreases in both ion transport and water permeability. Exudation was also inhibited at 10(-10) to 10(-7)m kinetin. Exudation from roots with intact tips was not altered by kinetin until after about 24 hours. Light during the exudation period had no significant (95%) influence on rate of exudation during the first 24 hours whether root tips were cut or kinetin applied.The results suggest the involvement of the root tip in regulating exudation in other parts of the root. This regulation might occur through cytokinin control of water permeability and the rate of ion transport.

Journal Article↗
PubMed1977

Reversal of induced dormancy in lettuce by ethylene, kinetin, and gibberellic Acid.

The germination of lettuce seeds (Lactuca sativa L., cv. Premier Great Lakes) was significantly inhibited by high temperature (32 C), 0.1 mM abscisic acid or 0.4 M mannitol. Ethylene (16 mul/1 of air) partially reversed the dormancy induced by all three inhibitors but only in the presence of 1 mM gibberellic acid (GA) or light. Neither ethylene plus GA nor ethylene plus light were able to promote germination when thermal inhibition was imposed at 36 C. Addition of 0.01 mM kinetin to the ethylene plus GA or light reversed thermodormancy at 36 C. The dormancy imposed by abscisic acid was also reversed by kinetin. Kinetin was unable to reverse the osmotic dormancy imposed by mannitol. The reversal of osmotic dormancy by ethylene or ethylene plus GA was actually inhibited by kinetin but only in the light. Kinetin apparently stimulates cotyledonary growth in the presence of light, and this growth may compete for certain metabolites critical to radicle growth and subsequent germination. Kinetin and ethylene, as demonstrated primarily in the thermodormancy at 36 C and in osmotic dormancy, appear to regulate a common event(s) leading to germination but through mechanisms unique to each respective growth regulator. The regulation of germination by ethylene is absolutely dependent upon an interaction with GA and/or light.

Journal Article↗
PubMed1987

Quantification of the kinetin effect on protein synthesis and degradation in senescing wheat leaves.

Wheat leaves (Triticum aestivum L. cv San Agustin INTA) were detached when they reached maximum expansion, put individually in tubes containing water and left in darkness. After 3 days the protein content had decreased to 46% of the initial value. When the leaves were placed in 1 micromolar kinetin, they retained 60% of the initial protein content for the same period. This effect was observed only when leaves were treated with kinetin within the first 24 hours after detachment. The action of kinetin on both protein synthesis and degradation was quantitatively measured. Synthesis was estimated by the incorporation of l-[(3)H]leucine into proteins. It was higher in kinetin treated than in non treated leaves. It contributed to about 14 micrograms of protein retention per leaf in 3 days. Measurement of protein degradation, evaluated by the decay of radioactivity in leaf proteins previously labeled with l-[(3)H] leucine or as the difference between rates of protein synthesis and protein content, showed that kinetin decreased protein breakdown rates. It accounted for about 186 micrograms of protein retention per leaf in 3 days. Hence, kinetin action on protein breakdown was 13-fold average higher than its action on synthesis for the conservation of leaf protein. This difference is higher in early stages of the process.

Journal Article↗
PubMed2000

Kinetin inhibits protein oxidation and glycoxidation in vitro.

We tested the ability of N(6)-furfuryladenine (kinetin) to protect against oxidative and glycoxidative protein damage generated in vitro by sugars and by an iron/ascorbate system. At 50 microM, kinetin was more efficient (82% inhibition) than adenine (49% inhibition) to inhibit the bovine serum albumin (BSA)-pentosidine formation in slow and fast glycation/glycoxidation models. Kinetin also inhibited the formation of BSA-carbonyls after oxidation significantly more than adenine did. However both compounds inhibited the advanced glycation end product (AGE) formation to the same extent (59-68% inhibition). At 200 microM, kinetin but not adenine, limited the aggregation of BSA during glycation. These data suggest that kinetin is a strong inhibitor of oxidative and glycoxidative protein-damage generated in vitro.

Adenine↗
PubMed1967

Translocation of radioactive kinetin.

Kinetin has generally been thought to be immobile in plants. This was confirmed in the case of laminar applications in this study, but not in regard to petiole, vein, or root applications. Radioactivity from kinetin-8-(14)C (Kn(*)) moved freely in the vascular system of several types of leaves. This movement was usually distal to the point of application and seemed to occur with the transpiration stream. Basipetal as well as acropetal translocation of radioactive kinetin was achieved in tobacco leaves. The translocated material was extracted from veinal tissue, shown to be radioactive, and to be able to retard senescence. Similar but less decisive results were obtained from agar blocks inserted into the vascular system of leaves receiving Kn(*) by petiole uptake.A bioassay employing disks from primary bean leaves was developed for the qualitative determination of substances like kinetin which possess the ability to retard chlorophyll breakdown and plant senescence. The use of radioactive kinetin provided a refinement in this bioassay because treated non-senescent areas could be correlated with exposed areas on radioautographs made from dried leaf disks.Root treatments showed that cotton seedlings did not take up Kn(*) but that similarly treated tobacco seedlings both absorbed and translocated the isotope readily.

Journal Article↗
PubMed1967

Correlative Studies on Plant Growth and Metabolism. III. Metabolic Changes Accompanying Inhibition of the Longitudinal Growth of Stem and Root by Kinetin.

Kinetin-induced expansion of lettuce (Lactuca sativa) cotyledons and inhibition of root are accompanied by parallel changes in protein nitrogen. However, during its inhibition of the longitudinal growth and water uptake of hypocotyl and pea (Pisum sativum) epicotyl sections kinetin markedly stimulates protein synthesis. Kinetin seems to separate auxin induced effects on protein synthesis and water uptake and indicates that water uptake and protein synthesis may not necessarily be correlated.In contrast to gibberellic acid, kinetin restricts in lettuce seedlings, the mobilization of nitrogen reserves from the cotyledons, and kinetin induced growth is accompanied by a high protein nitrogen/soluble-nitrogen ratio which is characteristic of growth in light. Growth in light may be under the dominant control of kinins.

Journal Article↗
PubMed1975

Additive and synergistic effects of kinetin and ethrel on germination, thermodormany, and polyribosome formation in lettuce seeds.

The inhibition of germination of Grand Rapids lettuce (Lactuca sativa L.) seeds at 35 C was removed to a marked extent by kinetin and 2-chloroethylphosphonic acid (ethrel). When both compounds were used together, an additive effect was observed. A synergistic effect was, however, noted when ethrel promoted the kinetin reversal of abscisic acid inhibition of seed germination (light- as well as gibberellic acid-, induced). Both kinetin and ethrel increased the total ribosomal material and the percentage of polyribosomes in lettuce seeds imbibed in the light for 24 hours. A combination of the two compounds showed a synergism in polyribosome formation only at high ethrel concentration. The inability of ethrel to reverse abscisic acid inhibition indicates that kinetin action cannot always be substituted by ethrel. The possible mechanisms involved in the enhanced response by a combination of kinetin and ethrel are discussed.

Journal Article↗
PubMed1976

Nonmetabolic catalysis of C-furfuryl amino purine (kinetin) on plant surfaces, glass, and porcelain ware.

Kinetin-8-(14)C degraded rapidly upon drying on living or inert surfaces. However, when care was exercised to avoid taking solutions to dryness during fractionation of plant extracts containing (14)C-kinetin and before partitioning by thin layer chromatography, little degradation occurred. A procedure for 24-hour ethyl acetate partitioning, using a continuous liquid-liquid extractor, which permits nearly complete removal of kinetin from aqueous solutions, is herein described. High natural light intensities in the greenhouse or from fluorescent/incandescent sources greatly enhanced nonmetabolic degradation of kinetin on leaf (Bougainvillea) or glass surfaces, which indicated that this may be a confounding factor in analyzing metabolism of kinetin in plant tissues. One of the degradation products is probably adenine.

Journal Article↗
PubMed1976

Promotive effects of organic solvents and kinetin on dark germination of lettuce seeds.

Significant promotion in dark germination was observed when Grand Rapids lettuce (Lactuca sativa L.) seeds were soaked in acetone or dichloromethane, vacuum-dried, and imbibed at 25 C. Permeation of kinetin via these organic solvents further enhanced the dark germination. Those seeds that were affected by acetone and acetone-kinetin treatments and germinated in the dark escaped red-far red photocontrol of germination. Although abscisic acid was not detected in the organic solvent leachates, they did contain other inhibitory substances affecting lettuce seedling growth. In the light, acetone and acetone-kinetin treatments also enhanced the rate of germination and the increased germination by acetone-kinetin treatment was correlated with increased polyribosome formation. The possible mechanisms involved in promotion of lettuce seed germination by organic solvents and kinetin are discussed.

Journal Article↗
PubMed1983

Kinetin increases water permeability of phosphatidylcholine lipid bilayers.

Kinetin is shown to increase substantially the water permeability of liposomes composed of several types of phosphatidylcholines including the natural phospholipids egg lecithin and asolectin and the synthetic phospholipids dimyristoylphosphatidylcholine and dipalmitoylphosphatidylcholine. Kinetin effects were measured from 16.3 micromolar to 2.4 millimolar at temperatures from 10 degrees C to 50 degrees C and at pH 2.0, 7.0, and 11.0. Temperature studies indicate that kinetin produces a larger increase in water permeability with membranes in the more fluid liquid crystalline state. Kinetin is also shown to enhance [(14)C]glucose permeability and perhaps promotes membrane aggregation. From these experiments, we conclude that kinetin may produce its initial effect by altering the lipid bilayer portion of membranes.

Journal Article↗
PubMed1990

Influence of kinetin on growth, flowering and alkaloidal contents of Hyoscyamus muticus L.

Plants treated with Kinetin responded very markedly and were more bushy and darker in colour than the controls. The physical yield was maximum in the plants treated with 50 PPM followed by 100 PPM and 200 PPM. Early flowering was induced in treated plants than the controls and it was seen first in 50 PPM. Growth and flowering was not very promising in higher concentration of the Kinetin. Height measurement indicated that plants treated with the Kinetin were larger than controls throughout the observation period. This indication was prominent in 50 PPM Kinetin treated plants followed by neat higher concentrations. Chemical assay has shown that the concentration of alkaloids has increased though it is not very appreciably as compared to the physical yield of each plant. Lower concentrations have better effects both on physical yield and alkaloids percentage as compared to the higher ones. From these observations it us assumed that the use of Kinetin as plant growth regulator on Hyoscyamus muticus is economical and its further investigations may prove more useful especially on other solanaceous plants.

Journal Article↗
PubMed1994

Alcohol dehydrogenase (EC 1.1.1.1) isozymes as markers at 2,4-dichlorophenoxyacetic acid x kinetin combinations in callus cultures of Cereus peruvianus (Cactaceae).

Alcohol dehydrogenase (ADH; EC 1.1.1.1) isozymes were investigated in tissue of Cereus peruvianus cultured in different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin. Five ADH isozymes were detected in starch gel and showed different patterns in seeds, seedlings, calli cultured at 32 and 22 degrees C, and plants regenerated from calli cultured in three 2,4-D and kinetin combinations. Four phenotypes formed by different combinations of ADH-2, ADH-3, ADH-4, and ADH-5 were detected in calli cultured at 32 degrees C and in plants regenerated from calli. ADH-1 isozyme was detected only in calli subcultured for 1 or 2 weeks at 22 degrees C and was indicated as a marker of stress conditions that affect the growth of C. peruvianus callus tissues in culture. ADH phenotypes with either a higher or a lower number of isozymes were detected in different proportions in the callus tissues cultured in media containing different 2,4-D and kinetin ratios. ADH isozyme patterns were found to be sensitive markers at the highest kinetin concentration or at high kinetin/2,4-D ratios. The results indicate a high correlation between the ADH isozyme patterns and the capacity for regeneration. Thus, ADH isozymes are indicated as good biochemical markers and as a powerful tool for monitoring studies of C. peruvianus callus cultures.

2,4-Dichlorophenoxyacetic Acid↗