Effect of External Supply of Growth Substances on Axillary Proliferation and Development in Dioscorea bulbifera

Bulbil development in cultured nodes of D. bulbifera proceededin the absence of growth substances from the medium. When IAAwas incorporated into the medium at the concentrations of 5mg l^–1 and 10 mg l^–1 the cultured nodes producedlarger bulbils than in its absences. When the concentrationof IAA was increased to 15 mg l^–1, however, the culturednodes produced a callus instead of a properly organized bulbil.The dry weight of bulbils increased when kinetin was added tothe medium at the concentrations of 0.05, 0.5, and 2.5 mg l^–1.The greatest increase was with 0.5 mg l^–1 kinetin. Onincreasing the concentration of kinetin in the medium to 5.0mg l^–1 the tissue produced had smaller dry weight thanthose produced in the absence of growth substances. Additionof different combinations of IAA and kinetin to the basal mediumresulted in the production of normal bulbils, roots, and shootsin some instances (suitable combinations) and in the productionof callus and abnormal shoots in others (non suitable combinations).     

Effect of kinetin on auxin uptake and distribution in normal and tumor-prone Nicotiana shoots

Stem segments of non-tumorous Nicotiana glauca and N. langsdorffiiplants and of their tumor-producing amphidiploid F₁ hybrid weretreated with 6-furfurylaminopurine (kinetin) prior to transporttests with applied labeled indoleacetic acid (IAA-2-¹⁴C). Kinetin-treatmentsincreased the uptake of IAA in non-tumorous shoots; the IAAuptake by N. langsdorffii segments was increased up to 3-fold.The auxin uptake in stem-segments of the tumor-forming hybrid,however, could not be increased significantly by kinetin. Theeven distribution of IAA-¹⁴C in segments of normal and tumorproneNicotiana shoots is stimulated by kinetin. Data are discussedin conjunction with previous results on auxin transport andtumorformation in Nicotiana. (Received August 8, 1972; )     

Low Temperature Treatments Induce an Increase in the Relative Content of Both Linolenic and {lambda}3-Hexadecenoic Acids in Thylakoid Membrane Phosphatidylglycerol of Squash Cotyledons

The effect of low temperatures on the fatty acid compositionof phosphatidylglycerol (PG) in thylakoid membranes, in particularon the ratios of nmol% 16:1(3t) (mg fresh weight)^–1 ofcotyledons and nmol 16:1(3t) (mg chlo rophyll)^–1 weremeasured during squash seedling growth. Plants were germinatedand grown for one day at 30°C then were either kept at 30°C(control plants) or trans ferred to low temperatures (18, 14or 10°C). When plant were transferred from 30°C to lowtemperatures, the increase in fresh weight was gradually limited.The lowe the temperature, the smaller was the fresh weight.In contrast, the relative content of 16:1(3t) and 18:3, as wella the ratios of nmol 16:1(3t) (mg chlorophyll)^–1 and mol%16:1(3t) (mg cotyledon fresh weight)^–1 increased indicatingthat the increase of fresh weight and chlorophyll was mor sensitiveto low temperature than PG desaturation in thyla-koid membranes.Furthermore, low temperatures inducei an increase in 16:1(3t)and 18:3 (the final products of PC synthesis) at the expenseof 16:0 and 18:1 (the initial products of PG synthesis). However,within a range of temperature from 10 to 18°C, the extentof these changes (nmol% of 18:3 or 16:1(3t) per day) was graduallylimited by lower temperatures. We therefore propose that lowtemperature inhibit both fatty acid synthesis and desaturationactivities. However, at low temperatures the fatty acid synthesisis likely to be more strongly inhibited than the desaturationactivities, thus explaining the observed increase in the relativecontent of PG-18:3 and PG-16:l(3t). Results an discussed interms of the mechanism which could be in volved in the metabolismof PG in squash cotyledons. (Received July 5, 1996; Accepted March 10, 1997)     

ROLE OF NUCLEIC ACID AND PROTEIN METABOLISM IN THE INITIATION OF GROWTH AT GERMINATION

When dry decotyledonized embryos of Raphanus are supplied withwater, a brief period of water absorption (phase A) is followedby a period of no fresh weight increase (phase B) which lastsfor 8 hr at 30°. In this period, embryos become ready toadvance into the period of fresh weight increase (phase C). When embryos were exposed to various concentrations of thiouracilor actinomycin D solution from 0 hr of water supply, increasesin fresh weight and in RNA content measured at 13 hr were inhibitedin parallel with each other. Chloramphenicol and puromycin inhibitedthe fresh weight increase without affecting the RNA increase.When embryos were exposed to thiouracil or puromycin for 2,4 and 6 hr, beginning at 0 hr of water supply, the start ofphase C delayed 2, 4 and 6 hr, respectively. When these drugswere given after phase B had progressed at least for 2 hr, thedelay of the start of phase C was shorter than the period ofthe drug treatment. If given at the end of phase B, thiouraciland actinomycin D inhibited the incorporation of ¹⁴C-uracilbut not the fresh weight increase, while chloramphenicol andpuromycin inhibited the latter without inhibiting the former. During phase B, protein content per dry weight of embryo didnot increase, but the rate of ¹⁴C-leucine incorporation increasedremarkably to reach the level in phase C. Incorporation of labeledleucine was inhibited if embryos were subjected to thiouracilor actinomycin D action during phase B, but not if the drugswere given when phase B had been completed. Puromycin and chloramphenicolinhibited the incorporation whenever they were given. The increase in respiratory activity during phase B was inhibitedrelatively little by the above mentioned four drugs. In conclusion syntheses of RNA and protein seem to be essentialfor the progress of phases B and C, protein synthesis havinga more direct effect. (Received September 17, 1965; )     

Studies on the stimulation of abscission by malformin on cuttings of Phaseolus aureus Roxb

White light irradiance required for complete and slight inhibitionof malformin-induced abscission by cuttings of Phaseolus aureuswas 13.5?10³ and 0.1?10³ ergs/cm^2. sec, respectively. Longerphotoperiods and higher irradiances were required to inhibitabscission by malformin-treated cuttings than by controls. Malforminstimulated dark abscission more rapidly, and at lower concentrations,than Ethrel or abscisic acid. The ability of light to inhibitmalformin-induced abscission diminished rapidly after 36 hrin the dark. Malformin accelerated chlorophyll and fresh anddry weight loss of leaves in the dark. The loss in fresh anddry weight, and perhaps chlorophyll, were inhibited by light.Hydroxyproline had little effect, but sucrose, hadacidin, kinetinand indoleacetic acid delayed malformin-induced abscission.Although puromycin, an inhibitor of protein synthesis, stimulatedabscission on controls, it inhibited malformin-induced abscission. (Received July 18, 1977; )     

Isolation, Culture, and Plant Regeneration of Protoplasts of Two Shrubby Oxalis Species from South America

Protoplasts were successfully isolated from internodal callustissues of both Oxalis glaucifolia and O. rhombeo-ovata whenthey were digested in a solution containing 0.1% (w/v) MacerozymeR-10, 0.5% (w/v) cellulase Onozuka R-10 and 0.3 mmol m^–3sucrose. Protoplasts proliferated to give cell colonies on Gamborget al.'s B5 medium supplemented with 0.3 mmol m^–3 mannitol,0.5 mg dm^–32, 4-D, and 2.0 mg dm^–3 kinetin. Calluswas produced upon transfer of cell colonies to Murashige andSkoog medium containing 2.0 mg dm^–3 l-naphthaleneaceticacid (NAA) and 0.1 mg dm^–3 kinetin for O. glaucifolia,or with 5.0 mg dm^–3 NAA and 0.5 mg dm^–3 6-benzylaminopurine,for O. rhombeo-ovata. Plants were regenerated from O. glaucifoliaprotoplasts on a medium containing 0.1 mg dm–3 NAA, 1.0mg dm^–3 kinetin and 1.0 mg dm^–3 gibberellic acid,but only vascular nodules were differentiated by O. rhombeo-ovataprotoplast-derived calli. Key words: Tissue culture, protoplasts, plant regeneration, Oxalis spp     

Effects of Cytokinin and Several Inorganic Cations on the Polyamine Content of Lettuce Cotyledons

Kinetin (4.7 x 10^–5 M) and 6-benzyladenine (2.22 x 10^–5M) were found to increase ca. 2-fold the putrescine contentin cotyledons of lettuce (Lactuca sativa L.) seedlings grownfor 3 days under fluorescent light. On the other hand, severalinorganic ions (K⁺, Na⁺, Ga⁺⁺, Mg⁺⁺) at a concentration of 3x 10^–2 M reduced the putrescine content. The combinationof kinetin with one of several inorganic ions at the same levelmarkedly increased the spermine content, but the putrescinecontent decreased; calcium and magnesium ions were less effective.The physiological significance of these findings is discussed. (Received July 4, 1982; Accepted November 6, 1982)     

EFFECTS OF CHLORAMPHENICOL AND KINETIN ON UPTAKE AND INCORPORATION OF AMINO ACIDS BY TOBACCO LEAF DISKS

The effects of chloramphenicol and kinetin on uptake and incorporationof ³⁵S-methionine and some ₁₄C-amino acids have been investigatedin leaf-disks of Nicotiana rustica in light and dark. Chloramphenicolin a concentration of 1 mg per ml inhibits the uptake of aminoacids from 30 to 60 per cent compared with the water control.The incorporation of amino acids into bulk protein is stronglyinhibited in light (40 to 70 per cent), but only to a smalldegree in dark (10 to 20 per cent), as revealed also by ¹⁴CO₂-photosynthesisof the disks and following treatment with chloramphenicol indark. The stimulating effect of kinetin on uptake and incorporationof amino acids is dependent upon its concentration (10^–5to 10^–6 M ; but 10^–4 M solution inhibits stronglyboth uptake and incorporation). The stimulation seems to influencemore incorporation than uptake processes. Possible interactionsof chloramphenicol and kinetin in the protein metabolism oftobacco leaves have been discussed. (Received April 27, 1964; )     

In vitro Propagation of Red Cabbage (Brassica oleracea L. var. capitata)

By manipulation of various growth regulators and physical conditions,plants have been regenerated from excised roots, stem segments,cotyledons, leaves, and callus cultures of red cabbage (Brassicaoleracea var. capitata) grown under in vitro conditions. Shootbuds were induced on isolated root segments (1 cm long) culturedon Murashige and Skoog's medium and the frequency of bud formationwas greatly enhanced by the addition of kinetin (0.5 part 10^–6).Callus obtained from the seeds, cotyledons, and hypocotyl segmentscultured on a medium fortified with 2,4-D (1 part 10^–6),kinetin (0.1 part 10^–6), and coconut milk (10%, v/v) hasbeen repeatedly subcultured. The callus is slow growing, andon transference to a kinetin (2 parts 10^–6) and IAA (2parts 10^–6) medium underwent morphogenesis to give riseto plants. The significance of the propagation of red cabbageby in vitro culture is pointed out.     

Effects of Cytokinins on the Nucleic Acids of Tobacco Pith

Cylinders of pith of Nicotiana tabacum var. Wis. 38 were asepticallyisolated and grown on a mineral-sucrose medium in the presenceand absence of either kinetin or zeatin. On medium containing kinetin (5x10⁶M) the increase in the residualdry weight of cylinders was greater than that on control mediumafter 2 d culture and this was maintained at 5 d. At 2, 5, and7 d there were increments in the DNA and RNA levels of cylindersdue to kinetin treatment and these increased progressively. A double-labelling method coupled with acrylamide gel electrophoresiswas used to study the effects of kinetin at 5 x 10^–6Mand zeatin at 10^–6 M on the incorporation of radioactiveprecursors into the RNA of cylinders given a 4-h label pulse.No effects of zeatin were observed after 1 d nor of kinetinat 2 d but after 4 d zeatin stimulated incorporation into ribosomal,transfer and poly-disperse RNA and kinetin did likewise after5 d. Incorporation measured at 7 d was reduced in cylindersfrom which kinetin had been removed at 5 d compared to thoseto which it had been supplied continuously. Scans at 260 run of the electrophoretic fractionations of RNAafter 2, 5, 7, and 9 d of culture showed that both in the absenceand in the presence of kinetin the proportion of 4S RNA increasedfrom about 20 per cent to over 50 per cent of the total between2 and 5 d of culture and after 5 d the ribosomal RNA gave aberrantscans apparently indicative of degradation. These aberrant scanspersisted in RNA extracted after 27 d culture in both the presenceand absence of kinetin.     

The Effects of Light Intensity and External Potassium Level on Root/Shoot Ratio and Rates of Potassium Uptake in Perennial Ryegrass (Lolium perenne L.)

Loliun perenne L. (cv.S. 23) was grown on vermiculite in winterin a heated greenhouse for 8 weeks under factorial combinationsof two potassium regimes (nominally 6 parts/10⁶ and 156 parts/10⁶in Hewitt's solution) and three densities of artificially supplementedvisible radiation flux (36.1, 7.3, and 2.2 W m^–2). Growthand potassium uptake were studied through the calculation ofvarious growth functions from fitted curves. There was little effect of potassium treatment but the experimentalmaterial responded markedly to light. Leaf-area ratio in thethree treatments showed extreme plasticity in increasing from2–3 x 10^–2 through 6 x 10^–2 to 8–9 x10^–2 m² g^–1 as light intensity decreased. Correspondingdecreases in unit leaf rate, however, caused over-all reductionsin relative growth rate. Specific absorption rates for potassium (A_K, dry-weight basis)were strongly reduced at the lower light intensities but alsodisplayed complex ontogenetic drifts. Values of the allometricconstant, k (the ratio of root and shoot relative growth rates),decreased from c. 0.7 at 36.1 W m^–2 through c. 0.3 at7.3 W m^–2 to a value not significantly different fromzero (P < 0.05) at 2.2 W m^–2. In material grown under the two higher light intensities a constantinverse relationship was found between the mass ratio of rootand shoot and the corresponding activity ratio. The resultsconform to this model: Mass ratio = –0.001+45.0 (1/activityratio) where activity ratio is expressed as specific absorptionrate for potassium (in µg g root^–1 h^–1)/unitshoot rate (rate of increase of whole-plant dry weight per unitshoot dry weight, in mg g shoot^–1 h^–1). The implicationsof this relationship are discussed.     

The Diurnal Pattern of Nitrate Uptake and Reduction by Spinach (Spinacia oleracea L.)

Spinach plants were grown in bowls of aerated nutrient solutionin a controlled environment chamber for 24 h, and harvestedevery 3·5-5 h to record their growth, nitrate and wateruptake, and plant nitrate concentration. Twelve such experimentsare described, either with a 14/10 h dark/light regime, or continuouslight or darkness. The irradiance was either 110, 320, or 510µmol m^-2 s^-1 (PPFD). All these regimes began at the endof the light period of a 14/10 h dark/light regime (510 µmolm^-2 s^-1) lasting approximately 2 weeks. Nitrate uptake rate per g of dry weight of plant continued almostunabated at about 17 µmol h^-1 through the initial 14-hdark period, and then fell away sharply if the light was notrestored, but increased slightly when it was. With continuouslight at 510 µmol m^-2 s^-1, uptake rate rose steadily forthe first 24 h of light, and then fell sharply for about 6 h.Shoot nitrate concentration increased about three-fold in thedark phase, and declined in the light at a rate which was positivelyrelated to the irradiance. Root nitrate concentration was severaltimes higher than that of the shoot: its diurnal change wassmaller (relative to the mean) than that of the shoot. Nitratereduction occurred to a small extent in the dark, and increasedrapidly as soon as the lights came on, to remain at a roughlyconstant rate (related to the irradiance) throughout the lightphase. Dry matter increase in the light was related to irradiance,but with little increase above 320 µmol m^-2 s^-1. Respiratoryweight loss in the dark was not detectable. Rate of fresh weightincrease was approximately constant throughout light and darkperiods. The results compare quite well with the predictions of a simplesimulation model, based on the pump/leak principle.Copyright1994, 1999 Academic Press Spinacia oleracea, nitrate, uptake, reduction, influx, efflux, diurnal, regulation, model, simulation     

Combined Effect of Some Growth Regulators on Growth and Gametangial Formation in the Liverwort Riccia gangetica Ahmad

The present work deals with the effect of IAA-kinetin, IAA-GA³and GA³-ABA interactions on growth and gametangial formationin Riccia gangetica in vitro. Inhibitory effect of high concentrationof IAA on vegetative growth is overcome by the co-addition ofkinetin. The best response in terms of fresh and dry weightyields of thalli is obtained by a combination of 10^–5mol dm^–3 kinetin+ 10^–7 mol dm^–3 IAA. Interactionof IAA and kinetin has an additive effect on archegonial formation.Co-addition of IAA and GA³ decreases production of archegoniaand antheridia as compared to those produced in response toIAA and GA³ alone, respectively. Combination of GA³ and ABAreduces vegetative growth, as well as the number of anthendiaand archegonia. Key words: Riccia gangetica, growth, growth regulators, gametangial formation     

Characterization of Senescence in Lemna gibba G3: A Determinate Growth System

Frond senescence in Lemna gibba G3 was characterized, and itscontrol by light, ABA and kinetin investigated. The plant exhibitsa determinate growth pattern with a frond producing a set numberof daughter fronds before undergoing senescence and death regardlessof whether or not it flowers. When a frond was cut in half,the distal half (half frond) which lacks any meristem underwentrapid senescence as compared with intact fronds. In both intactand half fronds, the onset of senescence was accelerated byABA and retarded by kinetin. Continuous white light acceleratedsenescence in both intact and half fronds over the dark controls.Under different photoperiodic light regime, the pace of daughterfrond production is accelerated in proportion to the lengthof light period. In half fronds, however, very short photoperiodiclight treatments (e.g. 1L: 23D or 3L: 21D) rather delayed senescenceover the dark controls. Two separate light control systems operatingin opposite directions in Lemana senescence appear to exist. ¹Present address: Department of Biology, Yonsei University,Seoul 120-749, Korea ²Present address: U.S. Department of Agriculture, Aero SpaceBuilding, Rm. 323, 901 D Street, S.W., Washington, D.C. 20251-2200, U.S.A. (Received July 13, 1989; Accepted May 8, 1990)     

Hormonal Control of Xylogenesis in Pith Parenchyma Explants of Lactuca

The time course of xylem differentiation was determined in explantsof lettuce pith parenchyma (Lactuca sativa L. cv. Romana) culturedon Murashige and Skoog (1962) medium using different concentrationsof auxin (IAA) and one cytokinin (zeatin or kinetin). Increasinglevels of auxin from I mg 1^–1 to 15 mg 1^–1 in thepresence of a constant level of a cytokinin (zeatin or kinetin)yielded up to 10 mg 1^–1 IAA, an increase in the numberof tracheary element formations. Cytokinin concentrations aboveand below o.1 mg 1^–1 interacting with an optimal xylogenicamount of auxin inhibited xylogenesis. The IAA (10 mg 1^–1)-zeatin(0.1 mg ^1–1) treatment produced the greatest number oftracheids, while kinetin compared to zeatin did not producesuch an effect. The different effectiveness of zeatin and kinetinin inducing tracheary element formations was not due to a differentcapacity of the two cytokinins to stimulate cell division butit seems likely that zeatin, because of interaction with IAA,is more active than kinetin in the determination of the dividingcells in a specific type of cytodifferentiation. The IAA (10mg 1^–1)-zeatin (0.1 mg 1^–1) treatment produced about6.9 per cent tracheids with respect to cell division while IAA(10 mg 1^–1)-kinetin (0.1 mg 1^–1) produced 4.2 percent. These results are discussed with reference to the problemsof hormonal control of xylem differentiation.     

Vegetable Plant Part Relationships. III. Modification of Carrot (Daucus carota L.) Root and Shoot Weights by Gibberellic Acid and Daminozide

Aqueous foliar sprays of N-dimethylaminosuccinamic acid (daminozide)at 2000 p.p.m. and gibberellic acid (GA) at 100 p.p.m. wereapplied 45, 59, 82 and 100 days after sowing to Chantenay carrotswith population densities of 244, 495 and 883 plants m^–2.The plants were harvested on ten approximately weekly occasions;fresh weights were determined and d. wt estimates were obtainedfor the separated shoots (s) and roots (r). Allometric linearregressions of the logarithm of s on that of r at each harvestseparately, clearly showed that GA always increased shoot: rootratio and reduced root yield (by approximately 35 per cent)but could sometimes also increase whole-plant weight. Daminozideincreased root yield (by approximately 7 per cent from 80 tonnesha^–1) and tended to have effects opposite to those ofGA. Daucus carota L., carrot, root weight, shoot weight, N-dimethylaminosuccinamic acid (daminozide), gibberellic acid     

Effects of Plant Growth Regulators on Grain-filling and Yield of Rice

Effects of three phytohormones (IAA₁, GA₃ and kinetin) on grain-fillingand the pattern of ³²P translocation from individual leavesto grains were studied at intervals of 7 days during the progressof reproductive development of rice (Oryza saliva L. cv. Jaya).The plants were sprayed with 100 µg ml^–1 aqueoussolutions of the hormones at 100 days, when the plants wereentering the reproductive stage. Kinetin produced a pronouncedeffect on grain-filling as well as on ³²P mobilization fromindividual leaf to grains and increased yield, possibly by increasingleaf longevity. GA₃ and IAA also increased the grain-fillingand ³²P mobilization significantly over control but the effectswere less marked than those of kinetin. Oryza sativa L., rice, grain yield, translocation, growth regulators, gibberellic acid, indol-3-yl acetic acid, kinetin     

Allocation of Photosynthate to Individual Tubers of Solanum tuberosum L.: III. RELATIONSHIP BETWEEN GROWTH RATE OF INDIVIDUAL TUBERS, TUBER WEIGHT AND STOLON GROWTH PRIOR TO TUBER INITIATION

Potato plants (Solanum tuberosum L.) were grown in water culture.About 14 d after tuber initiation no significant differenceswere found between apical and basal tuber parts in ¹⁴C-uptakeand partitioning into various fractions from ¹⁴C-labelled photosynthate.Thus, the fresh weight of these tubers could be used as a parameterfor the sink size. The ¹⁴C-content per tuber (sink strength)20 h after ¹⁴CO₂-supply to the foliage was significantly correlatedwith the tuber fresh weight. No correlation was found betweenthe ¹⁴C-concentration of the tuber (sink activity; ct. min^–g^– fr. wt.) and tuber fresh weight. Consequently, tuberfresh weight (sink size) per se must have been a factor whichinfluenced sink strength. Stolon parameters characterizing theirgrowth prior to tuber initiation (e.g. stolon volume) and theircapacity for photosynthate transport (diameter, length) weremeasured at the time of tuber initiation. Significant correlationswere found between these stolon parameters and subsequent growthof individual tubers. Anatomical studies on the proportion ofvarious tissues in the cross sectional area of stolons supportthe idea of a negative relation between growth of individualtubers and transport resistance in the phloem of the stolons.It is concluded that in the initial phase of tuber growth, mainlyfactors outside of the tuber determine its growth rate. In laterstages of tuber growth, when the sink strength increases, thecompeting strength of individual tubers for photosynthate isdominated mainly by factors within the tuber itself, such astheir sink size and sink activity. Key words: Potato tuber, sink size, tuber initiation, transport resistance     

Phytohormone-induced GABA production in transformed root cultures of Datura stramonium: an in vivo 15N NMR study

Primary nitrogen metabolism in transformed root cultures ofDatura stramonium was observed by in vivo ¹⁵N NMR. Treatmentof the root cultures with the plant growth regulators -naphthaleneaceticacid (NAA) and kinetin caused a de-differentiation of the roottissue, together with perturbation of primary and secondarynitrogen metabolism. The levels of newly-synthesized glutamineand glutamate during ammonium assimilation were depleted relativeto control cultures, whereas GABA biosynthesis was enhanced.Although GABA production could be stimulated by a decrease incytoplasmic pH (whether imposed artificially or induced by hypoxia),observation of the roots during phytohormone treatment by ³¹PNMR showed that the cytoplasmic pH remained stable, indicatingthat the perturbation of nitrogen metabolism in the de-differentiatedroots must be due to other causes. Key words: Datura, -aminobutyric acid, nitrogen metabolism, NMR, root cultures     

Uptake, transport and metabolism of cytokinin in moss protonema

Uptake, transport and metabolism of cytokinin in the protonemaof Funaria hygrometrica were studied using labelled kinetin(6-furfurylamino [8-¹⁴C]-purine). All cells of the protonema,chloronema and caulonema, were able to take up kinetin, whichwas carried in the symplastic transport system from cell tocell. Radioactivity was especially accumulated in growing cellsof the protonema. Kinetin was metabolized immediately afteruptake. While only very little kinetin (less than 1%) remainedas free kinetin and one part was immobilized in chromatographicseparation [e.g. attached to proteins and incorporated intonucleic acids (17)], most of the remaining kinetin was metabolizedto adenine derivatives. Exogenously supplied adenosine changedthe metabolism of kinetin. In the caulonema, adenosine reducedthe turnover of kinetin to other adenine derivatives and enhancedthe content of labelling in the start fraction. Thus adenosinecan stimulate cytokinin-dependent bud formation in moss protonema. (Received November 24, 1977; )