Showing papers on "Kinetin published in 1977"

The effects of aqueous seaweed extract and kinetin on potato yields

Abstract: In a trial conducted in 1974, foliar application of an aqueous seaweed extract of known cytokinin activity produced a significant increase in the yield of potatoes of the variety King Edward. A synthetic cytokinin, kinetin, also produced significant increases in the yield of tubers of both the varieties King Edward and Pentland Dell. There was close correlation between the results from the use of kinetin and the seaweed extract of equivalent cytokinin activity, which suggests that the effect of the seaweed extract was due to its cytokinin content. In a complementary trial in 1975 with King Edward potatoes, significant increases were obtained again in tuber yields through treatment with aqueous seaweed extract. The major increase was in ware potatoes.

Role of Cytokinins in Carnation Flower Senescence

Abstract: Stem and leaf tissues of carnation (Dianthus caryophyllus) plants appear to contain a natural antisenescence factor since removal of most of these tissues from cut carnation flowers hastened their senescence. However, kinetin (5-10 μg/ml) significantly delayed senescence of flowers with stem and leaf tissues removed. In addition, the life span of cut flowers with intact (30-cm) stems was increased with kinetin treatment. Peak ethylene production by presenescent flowers was reduced 55% or more with kinetin treatment and was delayed by 1 day. Kinetin-treated flowers were less responsive to applied ethylene (100 μl/l for 3 hours) than untreated flowers. Possible natural roles of cytokinins in carnation flower senescence are discussed.

Hormonal activity in detached lettuce leaves as affected by leaf water content.

Abstract: The interrelationship between water deficiency and hormonal makeup in plants was investigated in detached leaves of romaine lettuce ( Lactuca sativa L. cv. `Hazera Yellow9). Water stress was imposed by desiccating the leaves for several hours in light or darkness at different air temperatures and relative humidity. In the course of desiccation, a rise in abscisic acid content and a decline in gibberellin and cytokinin activity were observed by gas-liquid chromatography, by both the barley endosperm bioassay and radioimmunoassay and by the soybean callus bioassay. Gibberellin activity began to decline in the stressed leaves before the rise in abscisic acid, the rate of this decline being positively correlated with the rate of increase in leaf water saturation deficit. Recovery from water stress was effected by immersing the leaf petioles in water while exposing the blades to high relative humidity. This resulted in a decrease in leaf water saturation deficit, a reduction in abscisic acid content, and an increase in gibberellin and cytokinin activity. Application of abscisic acid to the leaves caused partial stomatal closure in turgid lettuce leaves, whereas treatment with gibberellic acid and kinetin of such leaves had no effect on the stomatal aperture. In desiccating leaves, however, gibberellic acid and kinetin treatment considerably retarded stomatal closure, thus enhancing the increase in leaf water saturation deficit. These results suggest that the effect of desiccation in changing leaf hormonal make-up, i.e. a rapid increase in abscisic acid and a decrease in both cytokinin and gibberellin activity, is related to a mechanism designed to curtail water loss under conditions inducing water deficiency.

Plant regeneration from shoot tips and callus of papaya

Abstract: Two methods of in vitro culture were employed to regenerate papaya plants. One involved regeneration of plants from callus and the other, production of multiple plants from single shoot-tip explants. Callus was induced from stem sections of papaya seedlings in a medium containing 1 mg per 1 NAA and 0.1 mg per 1 kinetin. The callus regenerated shoots and/or embryoids when transferred to a medium of lower auxin, 0 to 0.05 mg per 1 IAA, and higher cytokinin, 1 to 2 mg per 1 kinetin. Multiple shoots were produced when the excised shoot-tip explants were cultured in a medium supplemented with 0.05 mg per 1 IAA and either 5 mg per 1 kinetin or 0.5 to 1.0 mg per 1 benzyladenine. Root formation of the shoots or embryoids that derived from callus or shoot tips occurred in a medium containing 5 mg per 1 IAA and in a light intensity of 3000 to 4000 lx. The rooted plants could be established in soil and under standard greenhouse conditions after they had been acclimated by initially growing them in moist vermiculite contained in polyethylene-covered pots.

The hormonal control of cell wall turnover in pisum sativum l.

Abstract: SUMMARY A tentative structure for the polysaccharides of pea epicotyl cell walls is presented. The turnover of these polysaccharides has been followed by gravimetric and pulse chase studies. It is suggested that an important effect of IAA is the promotion of turnover in certain wall hemi-celluloses, notably xyloglucan; moreover, such turnover appears to be inhibited by kinetin. The relevance of these findings is discussed in terms of longitudinal and lateral cell expansion.

Repression of asexual embryogenesis in vitro by some plant growth regulators.

Abstract: A factor that represses asexual embryogenesis has been observed in the Rutaceae, with particularly high concentrations in the naturally monoembryonic cultivars. This investigation was an initial step towards identifying the factor.Citrus reticulata Blanco Ponkan mandarin nucellus explants andDaucus carota L. ‘Queen Anne's Lace’ callus were employed to examine effects of known plant growth regulators and to determine possible identity of one or more of them with the repressive factor. The chalazal halves of ovules ofC. media L. ‘Citron of Commerce’ were used as control repressor source. Embryo initiation and growth of both test tissues were depressed markedly by 2,4-D, abscisic acid and ethephon. Slight inhibitions were obtained with IAA, kinetin and gibberellic acid. Recovery from the repressor did not occur readily inCitrus nucellus following recultures in citron-ovule-free medium; carrot callus resumed normal embryogenesis immediately upon transfer to suppressor-free medium. The repression by natural sources apparently involved the combined action of some or all natural hormones that are generically related to the above.

Hormonal requirements of excised dianthus caryophyllus l. shoot apical meristem in vitro

Abstract: Whereas a medium containing kinetin alone enabled a few Dianthus caryophyllus L. apical meristem dome explants to develop into rooted plants, the highest frequency of plants was obtained in one containing supplements of both IAA and kinetin. In an unsupplemented medium, continued development required that explants have 2 pairs of primordial and a pair of expanding leaves. Kinetin alone caused production of many new leaves, but the development was significantly less than when it was furnished in combination with IAA. IAA given alone caused meristem explants to develop primarily callus, roots, and a few leaves. Gibberellin and abscisic acid were without promotive effects on leaf and shoot formation. A balance of hormonal substances, synthesized in young leaf structures and relocated to the meristem, is proposed as the fundamental mechanism that regulates new leaf initiation in the shoot apex. INVESTIGATIONS by Ball (1946, 1960) suggested that perpetuation of growth and organogenesis in excised angiosperm shoot apical meristems required subjacent stem and leaf primordia. More recently, Smith and Murashige (1970) were able to show that the subjacent structures were unnecessary. Starting with excised meristem domes less than 0.1 mm tall they were able to obtain complete plants of several herbaceous angiosperms, by using a simple nutrient medium that contained IAA (indole-3-acetic acid) as the only hormonal addendum. Detailed study (Smith, 1970) with Coleus blumei confirmed Ball's observations that no exogenous growth substances were required, if the explant consisted of the apical meristem together with 2 or more pairs of primordial leaves. However, provision of IAA was critical when leaf primordia were absent from the meristem explant. The significance of other hormonal substances remained unestablished. Smith (1970) observed that low concentrations of kinetin increased the frequency of surviving explants, but did not enable development of complete plants. Exogenous gibberellin (GA3) was observed to repress new leaf and root initiation and adenine appeared to reverse the repression slightly. In this investigation the roles of auxin, cytoI Received for publication 14 July 1976; revision accepted 26 October 1976. 2This paper represents a portion of a dissertation submitted in partial fulfillment of the requirements for a Ph.D. degree in Botany at the University of California, Riverside. The research was supported by the Elvenia J. Slosson Fellowship in Ornamental Horticulture awarded to T. M. The authors wish to thank Yanai Floral, Gardena, California, for the carnation cuttings, H. Quick for the photographs, and S. Ham-man and S. Kearns Sharp for typing the manuscript. kinin and gibberellin, as well as of abscisic acid, in morphogenesis of the shoot apex of the angiosperm, Dianthus caryophyllus L., has been examined more thoroughly. Furthermore, the findings have been applied towards elaboration of certain concepts associated with leaf initiation in the shoot apex. The carnation was employed because of its large and relatively easily isolatable meristem dome. MATERIALS AND METHODS-Terminal cuttings, 15-20 cm long, were obtained from greenhousegrown plants. All large leaves and lateral shoots were removed until there remained only the terminal meristem subtended by leaf primordia and 1-2 pairs of small leaves. The stem was shortened to 2 cm. The prepared cuttings in groups of 10 were wrapped in 10-cm squares of cheesecloth and transferred to 25 x 150 mm test tubes. A solution of 0.5 % sodium hypochlorite (commercial bleach diluted 10-fold and containing 2 drops Tween 20 emulsifer/100 ml) was added to the tubes to cover their contents. After 5 min the disinfestant solution was decanted and the contents of the tube were rinsed 3 times with autoclaved distilled water. Excision of the shoot apex tissues was performed in a horizontal laminar air flow hood. A Wild M5 dissecting microscope, with magnifications of 12.5-25 x, was used during the surgical manipulations. The excision was performed in a glass petri dish, lined with sterile, moist filter paper to retard dessication of the small explant. Severing of the meristem dome was accomplished with microscalpels made from razor blade slivers mounted on a Beaver chuck handle. The explant was lifted on the tip of the knife and transferred to a nutrient tube. The carnation apical meristem dome measured about 0.1 mm in height and 0.2 mm wide at the base.

Reversal of Induced Dormancy in Lettuce by Ethylene, Kinetin, and Gibberellic Acid

Abstract: 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 μl/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.

Defined conditions for the initiation and growth of cotton callus in vitro. I. Gossypium arboreum.

Abstract: Defined in vitro conditions for callus initiation byGossypium arboreum L. were determined, and different tissues were evaluated as explant sources. Environmental conditions tested included light versus dark, and low light versus high light. Different nutrient media as well as carbohydrate sources were examined. Our data show that hypocotyl tissue was superior to cotyledon or leaf tissue as the explant source for callus proliferation; the Murashige-Skoog inorganic formulation with (in mg per 1) 100 myo-inositol, 0.4 thiamine·HCl, 2 indoleacetic acid (IAA), 1 kinetin, and 3% glucose solidified by agar was the best medium to initiate callus. Cultures with sucrose as a carbohydrate source browned rapidly. Callus proliferation was superior under high light (8000 to 9000 lux) conditions at 29±1°C. Various combinations of auxins and cytokinins were tested for their ability to improve callus proliferation and subsequent growth of subcultures. Although the MS medium containing IAA and kinetin was found superior for obtaining rapid proliferation of callus from hypocotyl explants, a second medium containing 2 mg per 1 naphthalenacetic acid (NAA) and 0.5 to 1 mg per 1 benzyladenine (BA) was found necessary for vigorous growth of subcultured callus. A MS medium with 5 to 10 mg per 1 {ie329-1} (2iP) and 1 mg per 1 NAA was also favorable for continued subculturing.

In Vitro Formation and Development of Floral Buds on Tobacco Stem Explants Effects of Kinetin and Other Factors

Abstract: Stem segments were excised from plants of Wisconsin 38 tobacco (Nicotiana tabacum L.) in three regions differing in their distance below the inflorescence. They were cultured in vitro in 8- or 16-hr days. After 8 weeks, floral and vegetative buds were counted, and extent of floral development was assessed. Kinetin at 10−5m inhibited formation and development of floral buds regardless of indoleacetic acid concentration. Supplied at this concentration with adequate auxin, kinetin stimulated vegetative bud formation and may have caused floral bud abortion. Indoleacetic acid (≥ 10−6m) inhibited vegetative and floral bud formation when supplied with low kinetin concentration (≤ 10−7m) but did not affect floral development. When supplied with high kinetin concentration (≥ 10−6m), it inhibited floral bud formation and stimulated vegetative bud formation. More floral buds were formed in 16-hr days than in 8-hr days. Few formed on explants other than those derived from the region nearest the inflorescence regardless of other treatment.

Effect of Different Cytokinins on Ethylene Production by Mung Bean Hypocotyls in the Presence of Indole-3-Acetic Acid or Calcium Ion

Abstract: Kinetin has been shown to act synergistically with indole-3-acetic acid (IAA) or calcium ion (Ca2+) to stimulate ethylene production. Several commercially available cytokinins (kinetin, kinetin-riboside, benzyladenine, benzyladenine-riboside, isopentenyladenine, isopentenyladenine-riboside, and zeatin) as well as noncytokinin bases (adenine and xanthine) were administered to mung bean (Phaseolus aureus Roxb.) hypocotyls to study their effects, alone or in combination with IAA or Ca2+, on ethylene production. In the presence of IAA or Ca2+, all cytokinins tested synergistically stimulated ethylene production and were as effective or nearly as effective as kinetin. Noncytokinin bases (adenine and xanthine) were, however, inactive in this system.

18 μm replication units of chromosomal DNA fibers of differentiated cells of Pea (Pisum sativum)

Abstract: Explants of stelar and cortical mature pea root tissues were cultured on solid agar synthetic medium for up to 6 d. On the 3rd and 6th day the tissue was pulsed with 3H-thymidine from 15 up to 180 min to label the DNA. Subsequently the nuclei were isolated, lysed, and the DNA spread on microscope slides. The autoradiograms of labeled DNA fibers showed that the average replication fork traveled at 9 μm/h, and that an average of 18 μm of DNA separated activated origins. Nearly identical parameters were obtained from DNA of all callus independent of tissue source and independent of the presence or absence of kinetin in the medium.

Hill-acitivity and P700 concentration of chloroplasts isolated from radish seedlings treated with-indoleacetic acid, kinetin of gibberellic acid.

Abstract: The Hill-activity (reduction of DCPIP or methylviolgen) and the concentration of P700 were studied in chloroplasts isolated from cotyledons of radish seedlings (Raphanus sativus L. saxa Treib), which had been grown with the addition of beta-indoleacetic acid (IAA), kinetin, or gibberellic acid. 1) The photosynthetic activity of young chloroplasts from 3 day old Raphanus seedlings is very high (c. 180 micron mol O2/mol chlorophyll X h) and decreases continuously thereafter with increasing age. The steady state Hill-activity is reached after 8 to 10 days (values of 55 to 50 micron mol O2/mg chlorophyll X h). 2) Chloroplasts from plants treated with IAA or kinetin not only exhibit higher plastoquinone levels 1,2, but also a higher P700-content and a higher Hill-activity. The promotion effect is more pronounced with kinetin (+36 tb 40%) than with IAA (+12 to 17%). 3) Gibberellic acid has a different effect on composition and activity of chloroplasts. In younger seedlings the Hill-activity appears to be somewhat stimulated, without promotion effect on plastoquinone 2 or P700 concentration. After 10 days GA3-treated plants show signs of chlorosis combined with a strong decrease in photosynthetic activity. 4) The data clearly demonstrate that the composition and activity of the photosynthetic apparatus are under phytohormone control. IAA and even better kinetin promote the light induced formation of pigment systems and electrontransport chains. GA3 seems to block the rebuilding of the photosynthetic apparatus under steady state conditions.

Influence of Seed Pretreatments on Salt Tolerance of Cotton during Germination1

Abstract: One factor which limits crop production in the arid Southwest is the high salinity of soils and irrigation waters; especially during germination and early growth. The purpose of this study was to determine if salt-conditioning seed pretreatments would be effective in increasing the salt tolerance of cottonseed. Effects of 11 seed pretreatments on cotton (Gossypium barbadense L.) germination under saline and nonsaline conditions were studied in the laboratory to determine their usefulness in increasing relative salt tolerance. Salts, phytohormones, and adenosine monophosphate were used in seed pretreatments and their effectiveness was tested by germinating the pretreated seeds in single and mixed salts of NaCl and CaCL. Several pretreatments hastened germination under salinity by at least 1 day over nontreated controls. However, soaking in distilled water enhanced germination under saline conditions as much as any other pretreatment. Using original seed weight to determine drying time of seeds after pretreatment was inadequate because of gains or losses of solute during the soaking cycle. Additional index words: Gossypium barbadense, Gibberellic acid, Kinetin, Indole acetic acid, Adenosine monophosphate. L ONG-STAPLE cotton (Gossypium barbadense L.) is an important crop in many hot, arid environments where saline irrigation water is used. We conducted this study to determine it various seed pretreatments, such as have been described with wheat (4, 11), could effectively increase the salt tolerance of a commercial variety of long-staple cotton. Cotton pretreatment has not been studied as extensively as that of wheat and, whereas grains are very salt tolerant during germination and more sensitive during seedling and later growth stages, cotton is sensitive during germination and more tolerant during the later growth stages (2). Sometimes, costly management practices can minimize soil salinity problems during early plant growth but in some areas saline irrigation waters make salt stress unavoidable. Thus, the potential value of pre1 Contribution from [he U. S. Salinity Lab., ARS, USDA P.O. Box 672, Riverside, CA 92502. Received 8 Aug. 1976. 2 Research agronomist and agronomist, respectively. conditioning seeds to increase germination and seedling development is apparent. Typically, soil salinity delays normal development of root and shoot extension at germination (1). Prolonging this critical growth period increases chances of seedling damage by pathogenic or environmental factors. Furthermore, critical storage reserves within the seed are slowly depleted, causing decreased seedling survival and vigor. A beneficial and desirable consequence of seed pretreatment would be to maintain normal germination rate in the presence of salt. In 1883, Will and de Saussure (as cited in 17) used soaking and drying as a seed pretreatment before planting to increase drought tolerance. This technique was applied to increase salt tolerance by pretreating seeds in salt solutions (9). Since these early studies, soaking seeds in solutions that contain salts (4, 10), phytohormones (7) and other chemicals (10) has had many effects on germination and subsequent plant growth and development. Among the beneficial effects noted have been increased germination (4, 10), more rapid radicle elongation (17), more extensive root systems (7), increased yields and greater drought (8), cold (5, 6), and salt resistance (11). In 1924, Toole and Driimmond (19) described prewetting of cottonseed for improving germination in dry climates or of hard seed. They did not dry the seeds and they attributed better germination to a higher seed moisture content. Genkel (8) reported that seed treatment with 3% NaCl (0.5 N) increased yields of wheat and cotton 15 to 30% when grown in chloride-salted soils. Similar results have been reported for CaCl2 pretreatments in increasing wheat germination in NaCl medium (4). At low salinities, germination improved even when seeds were dried after pretreatment (11). This is important and essential because seed usually must be dry to be sown by mechanical planters and drills. MATERIALS AND METHODS A commercial lot of long-staple 'Pima S-4' cottonseed was used for all experiments. The acid-delinted, fungicide-treated seed tested 85% germination based on official germination methods. Germinat ion tests were made on blotters soaked in the appropriate solutions and then placed under and over the seeds Published July, 1977

The effect of kinetin on stomata of the grass Anthephora pubescens Nees

Abstract: Transpiration from excised leaves of Anthephra pubescens Nees was enhanced by 1 and 10 mmol m-3 kinetin. Stomatal opening in isolated epidermal strips of A. pubescens under CO2-free air and in the absence of K+ was enhanced by 10 mmol m-3 kinetin.

Establishment and growth characteristics of a cell suspension culture of Marchantia polymorpha L. with high chlorophyll content

Abstract: A green-pigmented cell suspension culture of Marchantia polymorpha was established using the medium of Murashige and Skoog with addition of organic acids of the tricarboxylic-acid cycle, vitamins and sugars plus sugar alcohols, exclusion of kinetin, and replacement of sucrose with glucose. In continuous light, the cells grew exponentially for ca. 10 days; in the dark, they grew only to a slight extent. The light-grown cells contained well-developed chloroplasts, and chlorophyll content reached almost twice that of the intact gametophyte.

Short-Term Metabolism of Radioactive Kinetin during Lettuce Seed Germination

Abstract: Exogenously applied 8-14C-kinetin is rapidly taken up by seeds of lettuce (Lactuca sativa L. cv. Grand Rapids). Radioactive metabolites were extracted and purified by solvent fractionation, column and paper chromatography. The primary metabolite was identified as the 9-riboside-5′-monophosphate. As germination proceeds, some kinetin is released from this bound storage form, giving a maximum level of free kinetin at 12 hours after imbibition. After this time the concentration of ribotide increases while the concentration of free base decreases. Other metabolites are the 9-riboside, AMP and IMP. It is suggested that a required amount of free base cytokinin is necessary by 12 hours after imbibition. This concentration of free cytokinin may act as a physiological trigger for later events during germination.

A Simplified Medium for the Growth of Maize (Zea mays) Endosperm Tissue in Suspension Culture

Abstract: In vitro cultures of maize (Zea mays L) endosperm derived from the dent inbred A636 have been maintained in liquid culture using Straus' medium for over six years We have studied the growth of this tissue in four basic media and various modifications of the organic constituents of these media Auxins and kinetin did not improve growth rate or degree of cell dispersion and thiamine (04 mg/l) was the only vitamin required by this tissue Growth equal to that in the standard Straus medium and improved cell separation was obtained in a medium containing only inorganic salts, sucrose, and thiamine Although asparagine was not required when high quantities of NH4NO3 and KNO3 were included, more rapid growth was obtained when 2 g/l of asparagine was added The simplified medium reported in this paper should facilitate the use of maize endosperm tissue in various studies of metabolism, hormone biosynthesis, etc