Showing papers on "Kinetin published in 1976"

Inhibition of ethylene production by cobaltous ion.

Abstract: The effect of Co(2+) on ethylene production by mung bean (Phaseolus aureus Roxb.) and by apple tissues was studied. Co(2+), depending on concentrations applied, effectively inhibited ethylene production by both tissues. It also strongly inhibited the ethylene production induced by IAA, kinetin, IAA plus kinetin, Ca(2+), kinetin plus Ca(2+), or Cu(2+) treatments in mung bean hypocotyl segments. While Co(2+) greatly inhibited ethylene production, it had little effect on the respiration of apple tissue, indicating that Co(2+) does not exert its inhibitory effect as a general metabolic inhibitor. Ni(2+), which belongs to the same group as Co(2+) in the periodic table, also markedly curtailed both the basal and the induced ethylene production by apple and mung bean hypocotyl tissues.In a system in which kinetin and Ca(2+) were applied together, kinetin greatly enhanced Ca(2+) uptake, thus enhancing ethylene production. Co(2+), however, slightly inhibited the uptake of Ca(2+) but appreciably inhibited ethylene production, either in the presence or in the absence of kinetin. Tracer experiments using apple tissue indicated that Co(2+) strongly inhibited the in vivo conversion of l-[U-(14)C]methionine to (14)C-ethylene. These data suggest that Co(2+) inhibited ethylene production by inhibiting the conversion of methionine to ethylene, a common step which is required for ethylene formation by higher plants.Co(2+) is known to promote elongation, leaf expansion, and hook opening in excised plant parts in response to applied auxins or cytokinins. Since ethylene is known to inhibit these growth phenomena, it is suggested that Co(2+) exerts its promotive effect, at least in part, by inhibiting ethylene formation.

Variation of Alkaloid Production in Nicotiana rustica Callus Cultures

Abstract: Callus cultures have been established from the seed, root and leaf of Nicotiana rustica L. var. brasilia in a synthetic medium containing 1 μM 2,4-D and μM kinetin. These callus tissues behaved similarly not only in growth and organogenesis but also in nicotine production. The nicotine contents of callus cultures, which were in the order of 0.25–0.58% of dry weight during a few passages subsequent to callus induction, rapidly decreased to trace amounts in succeeding subcultures in association with the decline of the root-regenerating activity. On the other hand, free cells prepared from a callus tissue in the third passage developed into individual clones showing wide differences in growth and nicotine production. One of these clones gave rise to a relatively stable strain which is capable of producing nicotine at a high rate (0.29% of dry weight) in the absence of organization. The significance of these findings is discussed in connection with some results which have been reported for other callus cultures of Nicotiana species.

Hormonal Control of Germination under Saline Conditions of Three Halophytic Taxa in the Genus Suaeda

Abstract: The interaction between hormones and salinity on seed germination of three halophytic taxa in the genus Suaeda: S. maritima (L.) Dum. var. flexilis Focke and var. macrocarpa Moq., and S. depressa (Pursh) Wats, was studied. Exogenous applications of kinetin and gibberellic acid (GA3) were applied in order to determine if either of these growth-promoting hormones would promote germination in the two dormant taxa, Suaeda depressa and S. maritima var. flexilis and to see if osmotically induced dormancy by NaCl could be alleviated. Our results indicate that gibberellic acid is capable of breaking dormancy in these species with dormant seeds, but kinetin proved to be ineffective. A seed dormancy that was induced by osmotic stress could also be alleviated by treatments with gibberellic acid. Endogenous concentrations of both cytokinins and gibberellins were measured in seeds exposed to osmotic stress (0.85 M NaCl), and we found a reduction in cytokinin activity in these three taxa. Gibberellin-like activity was reduced in S. depressa when seeds were soaked in 0.85 M NaCl.

Two sites of hormonal action during germination of Chenopodium album L. seeds

Abstract: During the overall germination process in the light-requiring seeds of Chenopodium album L. two sites of hormonal action can be distinguished. The start of visible growth is induced in darkness by the gibberellins 4 and 7 (GA4+7) or by ethylene. Added cytokinins are inactive although 8-14C-kinetin shows rapid penetration into the seed and rapid turnover. The induction of growth by GA4+7 and the uptake of 8-methylene-14C-GA3 are enhanced at lower pH values. Prolonged incubation in darkness results in a decreased responsiveness of the seeds towards GA4+7 and ethylene. A second site of hormonal action is located during the progress of growth inside the covering structures. ABA inhibits radicle growth, while GA4+7, GA3, kinetin, zeatin and ethylene reduce the inhibition.

Effect of Phosphorus Nutrition and Cytokinins on Flowering in the Tomato, Lycopersicon esculentum Mill

Abstract: Ten days of phosphorus deficiency results in a decrease in the number of flowers that develop on the first truss of tomato plants. This effect on flower number is accompanied by a decrease in the cytokinin activity of the root exudate. The involvement of cytokinins in flower development is further implicated by the fact that application of kinetin to the growing medium increased the number of flowers produced by the seedlings. Preliminary identification of cytokinins in root exudate has revealed the presence of compounds that cochromatograph with zeatin and zeatin riboside on Sephadex LH20.

Stimulation of Ethylene Production in the Mung Bean Hypocotyls by Cupric Ion, Calcium Ion, and Kinetin

Abstract: The synergistic stimulation of ethylene production by kinetin and Ca 2+ in hypocotyl segments of mung bean ( Phaseolus aureus Roxb.) seedling was further studied. The requirement for Ca 2+ in this system was specific. Except for Sr 2+ , which mimicked the effect of Ca 2+ , none of the following divalent cations, including Ba 2+ , Mg 6+ , Cu 2+ , Hg 2+ , Co 2+ , Ni 2+ , Sn 2+ , and Zn 2+ , showed synergism with kinetin on ethylene production. Fe 2+ , however, showed a slight synergism with kinetin. Some of them (Hg 2+ , Co 2+ , and Ni 2+ ) had a strong inhibitory effect, while others (Zn 2+ , Mg 2+ , Sn 2+ , and Ba 2+ ) had a slight or no inhibitory effect on ethylene production in the absence or presence of kinetin. Cu 2+ alone, depending on the concentration applied, stimulated ethylene production with a lag period of about 2 hours and had no synergism with kinetin on ethylene production. When Cu 2+ was applied with Ca 2+ , a remarkable synergistic stimulation of ethylene production was observed. Tracer experiments indicated that Cu 2+ enhanced the uptake of 45 Ca 2+ into the tissues during the first few hours of incubation, and this increase of 45 Ca 2+ uptake paralleled the enhancement of ethylene production. When Ca 2+ was applied together with kinetin plus Cu 2+ , both the ethylene production and the 45 Ca 2+ uptake were greatly increased over those from the segments treated with Cu 2+ or kinetin alone. The increase in ethylene production as a result of kinetin plus Ca 2+ plus Cu 2+ treatment is equal to the combined increases caused by kinetin plus Ca 2+ and Cu 2+ plus Ca 2+ . A possible mechanism accounting for such cooperative effects of Cu 2+ , Ca 2+ , and kinetin on ethylene production is discussed.

Development of Pollen Embryoids in Anther Cultures of Datura innoxia II. EFFECTS OF GROWTH HORMONES

Abstract: In anther cultures of Datura innoxia the addition of growth hormones, such as auxins, gibberellins, and cytokinins, to the culture medium enhanced the production of pollen embryoids. Cytokinins appeared to be the most effective and, among the four cytokinins tested, zeatin and kinetin gave the best results. Generally speaking, combinations of hormones did not improve the response over that of an individual hormone. The number of embryoids per anther varied in the same medium and did not strictly correlate with the percentage of respond ing anthers.

Germination of Coffee Seeds (Coffea arabica L. cv. Mundo Novo)

Abstract: The life-span of coffee seeds is extended when seeds are stored with high moisture content. Germination in darkness is always higher than in the light. Exogenous gibberellic acid and abscisic acid inhibit germination while kinetin reverses this inhibitory effect. Low levels of endogenous gibberellin- and abscisic acid-like and high levels of cytokinin-like substances favour germination while the opposite combination of regulators delays germination.

Clonal Propagation of Dioscorea Floribunda by Tissue Culture

Abstract: SummaryA tissue culture method for rapid clonal multiplication of Dioscorea floribunda Mart and Gal. is described. Nodal segments were used as initial explants. Plantlets were obtained on Murashige and Skoog’s basal medium supplemented with 2 ppm kinetin with or without 0·2 ppm a-napthaleneacetic acid.

Influence of the nutrient medium on the recovery of dividing cells from tobacco protoplasts.

Abstract: Systematic tests resulted in a nutrient solution containing the following, in milligrams per liter, for the culture of protoplasts isolated from Nicotiana tabacum L. callus cells: Murashige and Skoog salts (T. Murashige and F. Skoog, 1962. Physiol. Plant. 15: 473-497); sucrose, 15,000; mannitol, 110,000; alpha-naphthaleneacetic acid, 0.6; kinetin, 0-0.1; thiamine.HCl, 10; pyridoxine.HCl, 10; nicotinic acid, 5; myo-inositol, 100; and glycine, 2. In this medium, regeneration of cell wall has been observed in 85% and resumption of cell division among 35% of the protoplast isolates.

An assessment of the modifying effect of kinetin on in vitro tuberization of induced and non-induced tissues of Solatium tuberosum

Abstract: ‘Katahdin’ potato plants (Solatium tuberosum L.) were grown under inducing (26 °C day −12 °C night with an 8-h photoperiod) and non-inducing (28 °C day −25 °C night with a 16-h photoperiod) conditions. Apical, medial, and basal nodal stem segments from each plant harvested were surface sterilized and aseptically transferred to culture flasks containing Murashige and Skoog's medium with and without kinetin. After culturing in dark for 4 weeks at 24 °C, percentage tuberization of segments from induced plants was significantly greater than for non-induced segments. Addition of kinetin to the culture medium eliminated this effect of induction. Apical segments from induced plants tuberized more frequently than those from non-induced plants and those from lower on stem. Addition of kinetin eliminated this stem position effect. Percentage elongation was significantly greater in segments from non-induced than induced plants. Addition of kinetin reduced percentage elongation in non-induced segments to that for ind...

Rhythmic Nitrate Reductase Activity in Leaves of Capsicum annuum L. and the Influence of Kinetin

Abstract: In the expanding leaves of Capsicum annuum L. cv. California Wonder, two of the three peaks of nitrate reductase activity associated with the light period exhibit a circadian rhythm that persists in continuous light.The spray application of kinetin to the whole shoot or to leaves other than the ones used for nitrate reductase assay causes a phase shift in the activity peaks and this has been used in preliminary investigations of the character of the mechanisms controlling the timing of the peaks.There was some indication that the rate of translocation of nitrate from the roots might be involved. The levels of nitrate moving up the stem after kinetin treatment were more dependent upon the rate of sap flow than on the concentration of nitrate in the sap. For this reason, transpiration rates in whole plants were measured after kinetin treatment but no change in pattern was seen that would correlate with the phase shift in nitrate reductase activity.The occurrence of nitrate reductase peaks in excised leaves suggested a leaf-based in addition to a root-or stem-based mechanism in the timing of nitrate reductase activity in the leaves.

Effects of Nitrogen, Sucrose, IAA and Kinetin on Explants of Beta vulgaris Grown in vitro

Abstract: Hypocotyl explants of Beta vulgaris L. were grown on defined agar media with different combinations of IAA and kinetin at varying concentrations of nitrogen or sucrose. The cultures were kept in light (18 h a day) at 27°C for 5 weeks. Root initiation and callus growth were recorded and the callus tissue was analysed for N and K. Root formation was found to increase with increasing nitrogen concentration (from 5 mM to 23.3 mM) in the medium at 10.0 mg/1 of IAA, whereas no stimulation was found at 0.1 mg/1 of IAA. When raising the sucrose level from 20 g/1 to 100 mg/1 at 10.0 mg/1 of IAA and 1.0 mg/1 of kinetin, root initiation was also stimulated. At a lower kinetin and auxin level, however, no increase was recorded. Callus growth was affected by changes in the nitrogen or sucrose concentration of the culture media. The nitrogen content of the callus tissue increased with rising nitrogen concentration of the media. When raising the sucrose level instead of the nitrogen level, the nitrogen content of the tissue decreased.

Kinetin action on the development of microbody enzymes in sunflower cotyledons in the dark.

Abstract: Removal of the roots from etiolated sunflower seedlings (Helianthus annuus L) at various stages of development resulted in a premature or enhanced decline of the activities of catalase (EC 11116) and isocitrate lyase (EC 4131) (glyoxysomes), and hydroxypyruvate reductase (EC 11126) and glycolate oxidase (EC 1131) (leaf peroxisomes) in the cotyledons Treatment of the cuttings with kinetin in the dark inhibited the loss of glyoxysomal enzyme activities and, at the same time, induced a three to fivefold increase in leaf-peroxisomal enzyme activities The decline of glyoxysomal enzyme activities was also suppressed after application of both kinetin and cycloheximide (50 μg/ml) The kinetin-mediated rise of leaf-peroxisomal enzyme activities was strongly curtailed in the presence of cycloheximide The dose effect curves of kinetin action on the development of glyoxysomal and of leaf-peroxisomal enzyme activities were different, supporting the hypothesis that the mechanisms of kinetin action on the two microbody enzyme systems are different Nitrogen nutrition of intact seedling effected the development of microbody enzyme activities in a pattern closely resembling that of kinetin action Presumably endogenous cytokinins produced by the roots are involved in the regulation of microbody enzyme activities in cotyledons of dark-grown sunflower seedlings

Influence of Different Cytokinins on the Germination of Lettuce (Lactuca sativa) and Celery (Apium graveolens) Seeds

Abstract: The naturally occurring cytokinins, zeatin, zeatin riboside and dihydrozeatin did not promote the germination of celery (Apium graveolens L.) seeds and 6-Δ2-isopentenyladenine (2iPA) and its riboside were only moderately active. Of the synthetic cytokinins, kinetin, kinetin riboside, and the disubstituted urea, N-phenyl-N′-pyridyl urea (NC5392) were moderately active, and 6-benzyl-aminopurine (BA) and its derivatives BA riboside and 6-benzyl-amino-9(tetrahydropyran-2yl)purine (SD8339) were the most active cytokinins tested. 6-(o-hydroxybenzyl)aminopurine (hyd-BA) and its naturally occurring riboside inhibited germination under normally inductive conditions. All the cytokinins examined were more active in promoting germination of lettuce (Lactuca sativa L.) than celery seeds. BA, BA riboside and SD8339 were again the most active cytokinins. In contrast to the results with celery, zeatin and zeatin riboside were highly active. The other cytokinins also showed high activity with the exception of dihydrozeatin, hyd-BA and hyd-BA riboside which were less active. Cytokinin ribosides were less active than the corresponding free bases during the early period of the lettuce seed incubation but total germination after 90 h was similar.

Genotype-hormone interaction in the induction of chromosome aberrations: Effect of 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin on tissue cultures from nicotiana SPP. ☆

Abstract: The effect of a synthetic auxin-like substance (2,4-D) and a synthetic cell division factor (kinetin) on the induction of chromosome aberrations was studied on tissue cultures of Nicotiana glauca and the tumorous amphidiploid hybrid Nicotiana glauca × Nicotiana langsdorffii The aberration frequencies in normal Nicotiana glauca tissue were proportional to the length of time of culture in the presence of 2,4-D Moreover, both 2,4-D and kinetin increased chromosome breakage in the habiatouated Nicotiana glauca tissue but not in the amphidiploid hybrid tissue The data are discussed in terms of genotype-hormone equilibria in long-term development of plant tissue culture

Development of Pollen Embryoids in Anther Cultures of Datura innoxia

Abstract: In anther cultures of Datura innoxia the addition of growth hormones, such as auxins, gibberellins, and cytokinins, to the culture medium enhanced the production of pollen embryoids. Cytokinins appeared to be the most effective and, among the four cytokinins tested, zeatin and kinetin gave the best results. Generally speaking, combinations of hormones did not improve the response over that of an individual hormone. The number of embryoids per anther varied in the same medium and did not strictly correlate with the percentage of respond ing anthers.

Leaf cell water and enzyme activity

Abstract: This work supports further the thesis that under conditions of water stress, cell water content may supersede hormonal regulation in effecting enzyme activity, thus becoming a regulatory factor in cellular metabolism. Addition of NaCl to the root medium of barley plants (Hordeum vulgare L.) markedly increased leaf RNase activity parallel to an increase of leaf water saturation deficit (WSD). Kinetin and abscisic acid, applied to the salinated plants, also modified RNase activity, as well as leaf-WSD. The familiar pattern of effects of these hormones on leaf RNase as well as leaf chlorophyll content was inverted, kinetin effected a relative increase in RNase activity and a decrease in leaf chlorophyll, whereas abscisic acid effected a relative decrease in RNase activity and maintained chlorophyll content. A close relationship between enzyme activity and leaf WSD became evident when leaf RNase and protease activities in the salinated plants were plotted against leaf WSD. This close relationship was maintained irrespective of the hormonal treatments, which in themselves markedly modified leaf WSD. As predicted, high relative humidity which relived the leaves from salt-induced water stress prevented the salt-induced rise in RNase activity.

Embryogenesis and Differentiation in Nigella sativa Leaf Callus in vitro

Abstract: Embryogenesis occurred in Nigella sativa L. (Fam. Ranunculaceae) leaf callus tissue when coconut milk was replaced from the Murashige and Skoog's (MS) medium by casein hydrolysate. On MS + IAA (0.5 mg/l) + casein hydrolysate (100 and 500 mg/l) medium, tissue gained a capacity of growing embryoids for a pro-longed culture period. At a concentration of 1000 mg/l casein hydrolysate suppressed the differentiating capacity after the fifth subculture. 2.4-D and kinetin had inhibitory effects on morphogenesis. Histology of the differentiated tissue revealed that the origin of roots, shoot buds and leaves were from groups of meristematic cells whereas embryoids were initiated by the repeated division of a single cell.

Influence of hormonal treatments on the growth of two halophytic species of suaeda

Abstract: A B ST RA CT Experiments were made to determine the interaction between the growth regulating substances, gibberellic acid and kinetin, and salinity on the growth and development of two species of Suaeda. We found that the growth of Suaeda maritima var. macrocarpa, an obligate halophyte, was greatly stimulated with treatments by both of these hormones in controls not treated with sodium chloride. These results suggest that halophytes grow poorly under nonsaline conditions because of some type of hormonal imbalance. GA3 was found to stimulate growth at all salinities for both S. maritima var. macrocarpa and S. depressa, while kinetin proved to be inhibitory to growth and elongation of plants at higher salinities. Chlorophyll content decreased with salt treatments and was not significantly influenced by hormonal treatments. GA3 had little influence on water content in roots and shoots, whereas plants treated with kinetin gen