Metabolism of N-(purin-6-yl)glycine by Soya Bean Callus

The growth of cytokinin-dependent soya bean callus has beenshown to be accelerated by adding N-(purin-6-yl)glycine to themedium. Two biologically active peaks were detected when thecallus was cultured with N-(purin-6-yl)glycine. These two peaksco-chromatographed with 6-(2, 3, 4-trihydroxy-3-methylbutylamino)purineand zeatin respectively. When ¹⁴C labelled N-(purin-6-yl)glycinewas applied to the callus, radioactivity was found with boththese compounds irrespective of whether or not the N-(purin-6-yl)glycinewas labelled in the side chain or in the 8-position of the purinering. Small amounts of zeatin appear to be produced from N-(purin-6-yl)glycinewhich could explain why this compound stimulates the divisionof soya bean callus. N-(purin-6-yl)glycine, soya bean callus, metabolism, radioactivity, cytokinins     

Unusual features of respiration in mixotrophic green tobacco callus tissues

Respiratory activity of green tobacco callus tissue from thepith of Nicotiana tabacum var. Samsun was influenced by light.Interruption in the light period resulted in a decrease in respiratoryactivity after a lag period of about 2 hr. The respiration levelincreased on re-illumination and was restored to its originallevel after 2–3 hr. The light effect that increased respiratory activity was enhancedby sugar in the medium and by increasing the light intensity.However, the response to light was not affected by an inhibitorof photorespiration and was suppressed completely by an inhibitorof photosynthesis. (Received August 9, 1978; )     

Benzyladenine-Enhanced Cell Proliferation and -Suppressed Greening in Attached Young Bean Leaves

Changes in fresh weight, cell number, cell size and cell constituentswere studied during the growth of attached young bean (Phaseolusvulgaris L.) leaves after benzyladenine (BA) treatment. BA broughtabout the increase in DNA, RNA and protein contents and freshweight as well as the temporary inhibition of chlorophyll accumulationin growing leaves. After a lag period for about 12 hr, BA stimulatedcell division but not cell expansion. An increase in RNA contentoccurred during the lag period of BAinduced cell division growth. (Received November 5, 1980; Accepted March 10, 1981)     

Genotype Affects the Morphogenic Response in vitro of Epicotyl Segments of Citrus Rootstocks

The influence of light, hormones and explant orientation onin vitro regeneration in epicotyl cuttings was compared in fourCitrus species (C. aurantium, C. macrophylla, C. reshni andC.sinensis ) and the hybrid Troyer citrange (C. sinensis x Poncirustrifoliata). In all cases, explants planted vertically regeneratedshoots at the apical end by a process of direct organogenesiswithout callus formation. When the Troyer citrange explantswere incubated horizontally, regeneration at the apical endoccurred by an indirect organogenic pathway after callus formation.This change in the pathway of regeneration did not occur inany of the Citrus species, and incubation horizontally resultedin a reduction in the number of buds and shoots formed throughthe direct organogenic pathway. Shoot formation through thedirect organogenic pathway was inhibited by darkness, and thisinhibitory effect was counteracted by the cytokinin benzyladeninein Troyer citrange and, partly, in C. sinensis, but not in C.macrophylla. A non-organogenic callus formed at the basal endof most of the cuttings of C. reshni. InC. sinensis and C. aurantium,a non-organogenic callus formed only in a low proportion ofexplants. Troyer citrange formed an organogenic callus in whichbuds or roots differentiated depending on the auxin/cytokininbalance. C. macrophylla formed callus in the dark but not inthe light. Root formation occurred both in the presence of theauxin naphthaleneacetic acid or low concentrations (2.2 to 4.4µM) of the cytokinin benzyladenine, but no buds were formed.These qualitative and quantitative differences in the organogenicresponse indicate that the conditions for regeneration mustbe optimized for each genotype. Copyright 2000 Annals of BotanyCompany Benzyladenine, citrus, Citrus aurantium, Citrus macrophylla, Citrus sinensis, Citrus sinensis x Poncirus trifoliata, naphthaleneacetic acid, organogenesis, rooting, shoot regeneration, Troyer citrange     

Alteration of the respiratory function in chill-sensitive callus due to low temperature stress: Involvement of the alternate pathway

The diversion of electron flow to the alternate pathway in mitochondriaof chillsensitive callus of Cornus stolonifera was studied withreference to the immediate response of the cells to chilling.Temperatures below 15?C diverted the bulk of respiration tothe alternate path, proportionally as the temperature decreasedto 0?C. The alternate path, however, existed in cells in a suppressedform at temperatures above 15?C. In chill-resistant callus ofSambucus Sieboldiana, no alteration was noted in electron apportionmentbetween the cytochrome path and the alternate path. Thus, thereseems to be a marked difference in the mode of respiration betweensensitive and resistant plant cells at low temperatures. Therespiratory control ratio also markedly declined at temperaturesbelow 15?C in chill-sensitive callus, but a higher respiratorycontrol ratio was observed below 10?C in chill-resistant callus.From these results, an alteration in the regulatory system forelectron apportionment between the two paths is probably themost immediate response of chill-sensitive cells to low temperatures. ¹Contribution No. 2154 from the Institute of Low TemperatureScience. (Received June 6, 1979; )     

Endogenous light-on rhythm in respiration of a long-day duckweed, Lemna gibba G3

1. The rate of O₂-uptake of Lemna gibba G₃ changed with a dampeddiurnal rhythm under continuous illumination given after shortdays. The rhythm was started by a light-on stimulus with a 6hr lag period and is thought to be under the control of a biologicalclock. 2. The 6 hr lag period was replaceable with a 6 hr dark periodinterrupted twice (at 0 and 3 hr) by a brief illumination withred light. The effect of red light was removed by immediateexposure to far-red light. This effect of far-red was reversedby subsequent red light. The 6 hr lag may involve a phytochrome-mediatedreaction which may be preparatory to the induction of this rhythm. (Received December 13, 1969; )     

The Effect of Adenine and Mevalonic acid on the Endogenous Cytokinins of a Cytokinin-dependent Strain of Soya Bean Callus

The combined application of 10^–6 M adenine and 10^–6M mevalonic acid to soya bean callus accelerated its growth.Two biologically active compounds that co-chromatographed withzeatin and isopentenyl adenine were extracted from this callus.Studies with labelled adenine and mevalonic acid indicated thatthe cytokinin-dependent soya bean callus incorporated only avery small amount of the radioactive precursors into the biologically-activecompounds, making it extremely difficult to determine whetherthese compounds were synthesized de novo or whether they aroseas by-products of tRNA turnover. As cytokinins do not accumulatein rapidly-growing cytokinin-dependent soya bean callus culturedon kinetin as a source of cytokinin it seems as if biosynthesisde novo occurs when the callus is supplied with adenine andmevalonic acid. Glycine max (L.) Merrill, soya bean, callus culture, adenine, mevalonic acid, endogenous cytokinins     

Influence of Environmental Stress on the Germination of Anabaena vaginicola Akinetes

Germination of akinetes of Anabeana vaginicola v. fertilissimaPrasad in response to environmental stress was studied. Additionof nitrate to the medium induced early and maximum germination(96 per cent), whereas less than half of the akinetes germinatedwhen either nitrate or phosphate was omitted from the medium.The pH range over which germination occurred was 7.0–9.0.The desiccated akinetes after rehydration germinated after acertain lag period, depending upon the dehydration state. Thetemperature optimum for germination and vegetative growth wasthe same (25 °C) and germination did not occur at 5 °Cor above 35 °C. The limit of heat shock tolerated was 55°C for 4 min. In addition to white light, only the red partof the visible spectrum induced germination. Ultraviolet radiationreduced germination rate presumably by inducing thymine dimersin DNA. The photoreactivating system (s) in akinetes is certainlynon-photosynthetic. LD₅₀ photon flux densities were 300 Jm^–2for akinetes and 240 Jm^–2 for vegetative cells. Anabaena vaginicola, blue-green alga, akinete, germination, environmental stress     

Effect of Method of Agar Addition on Post-autoclave pH of the Tissue Culture Media

Tissue culture media (MS, GB-5 and N6) were gelled with agarby employing different methods When agar was dissolved directlyin media by autoclaving at 120 °C for 1 mm followed by sterilization,the media pH dropped markedly — more so at the lower concentrationsof agar On the other hand, when agar was first dissolved indistilled water and added to the culture media the pH loss wasminimized considerably pH measurements carried out as a functionof time showed a gradual decline in media pH The media supplementedwith Panax ginseng callus became more acidic than the mediawith no callus Tentative reasons for the post autoclave pH fallassociated with various methods of agar addition are described Culture media, agar addition, post-autoclave pH, Panax gingseng     

Vernalization in Lolium temulentum L.: Responses of In Vitro Cultures of Mature and Immature Embryos, Shoot Apices and Callus

Response of vernalization to low temperature (2C) was studiedin a winter-annual form of Lolium temulentum L., using imbibedseeds, excised mature and immature embryos, shoot apical meristemsand callus tissue. Excised embryos, as early as 5 days afteranthesis, and excised shoot apices could be vernalized as effectivelyas imbibed seeds. Cold treatment of developing embryos withinthe ear, however, appeared to have no vernalizing effect. Plantsderived from callus by somatic embryogenesis showed varyingdegrees of vernalization response. The vernalization response in L. temulentum, as in winter annualcereals, appears to be located in the shoot apical meristemand the vernalized condition can be transmitted to new axillarymeristems formed from it. Lolium temulentum L. darnel, vernalization, embryo culture, apical meristem culture, callus culture     

Effect of Ethylene and Culture Environment on Rice Callus Proliferation

Modifications to the gaseous envelope by callus during culturein Petri dishes were shown to reduce growth and promote necrosisof several rice (Oryza sativa L.) cultivars. Incubatingcallusunder a continuous flow of gas mixtures of known compositionsuggested that the inhibition of growth was caused by the accumulationof ethylene, the depletion of oxygen and, to a lesser extent,the accumulation of carbon dioxide. In order to evaluate theimportance of ethylene accumulation aminoethoxyvinylglycine(AVG), 1-aminocyclopropane-l-carboxylic acid (ACC and silvernitrate (AgNO₃), were added to the nutrient medium and ethylenemeasurements performed during callus culture. Ethylene restrictedcallus growth particularly under high (35 °C) as comparedto moderate (25 °C) temperatures and under illuminated ascompared to darkened incubation. Under illuminated incubationat 25 °C AVG (5 mmol m^–3) and AgNO°(50 mmol m^–3)significantly improvedcallus growth (100 and 60% respectively)while ACC (200 mmol m^–3) significantly decreased growth(40%). AVG and AgNO₃ were less effective under dark incubationat 25 °C where ethylene production was lower. Furthermore,callus growth was significantly better in large as comparedto small culture vessels since the ethylene concentration wasdiluted and more oxygen was available for respiration. Bettercontrol of ethylene and increased oxygen availability couldbe a way ofproducing healthy callus for the formation of embryogenictissues of otherwise recalcitrant cultivars of rice (e.g. IndicaIR42) and may be a way of improving manipulation of other cerealspecies. Key words: 1-Aminocyclopropane-1-carboxylic acid, aminoethoxyvinylglycine, callus, ethylene, Oryza sativa, silver nitrate     

A Corn Tissue Culture Cell Line with Altered Lipid Metabolism

A variant corn callus line derived from callus which originatedfrom etiolated leaves of Illinois High Oil corn (Zea mays L.)has been identified. The variant corn callus line had increasedlipid content concomitant with increased acetyl-CoA carboxylaseactivity and altered biotin-con-taining protein patterns relativeto the wild type callus. The variant callus line also had alteredfatty acid composition concomitant with decreased oleate desaturaseactivity compared to the wild type callus. The altered variantcorn callus line has been designated High Oil Callus (HOC). ¹Part of a dissertation submitted by Y.C.H. to the Universityof Illinois in partial fulfillment of the Ph.D. degree. Thispaper reports results of research only and the research wassupported in part by the University of Illinois, College ofAgriculture Fellowship awarded to Y.C.H. Mention of a trademark,proprietary product, or vendor does not constitute a guaranteeor warranty of the product (Received September 18, 1990; Accepted May 21, 1991)     

Studies on plant tissue cultures I. Relationship between inocula sizes and growth of calluses in liquid culture

1. 1. It was observed that lag of growth was longer in small inoculathan in large inocula using tobacco callus in liquid culture.
2. 2. These different growth responses between small and largeinocula were dependent on the ratio of inoculum to culture medium.
3. 3. The same result was obtained in a strain of carrot rootcallus.But the growth lag was very short in the carrot callus,whichwas subcultured for the shortest period among the 4 strainsused, even in small inocula. On the other hand, both small andlarge inocula of the strain, which were subcultured for thelongest period among the 4 strains, did not grow at all duringthe culture period; the longer the period of subculturing, thelonger the lag of growth.
4. 4. The longer lag of small inoculain tobacco callus was recoveredby gibberellin A₃ in the presenceof the acidic fraction ofcarrot root extract or vitamins suchas pyridoxine and thiamine.

(Received December 11, 1967; )     

Nuclear DNA Content as an Index Character Discriminating Taxa in the Genus Petunia sensu Jussieu (Solanaceae)

Nuclear DNA contents over the total range of the genus Petuniasensu Jussieu comprising 20 taxa of Petunia sensu Wijsman (2n = 2 x = 14) and 32 taxa of Calibrachoa(2 n = 2 x = 18) wereestimated by flow cytometry after staining the nuclei with propidiumiodide (PI) or 4',6-diamidino-2-phenylindole (DAPI). With respectto nuclear DNA content, taxa of Petunia sensu Wijsman seemedto be homogeneous (2C = 2.60 to 3.41 pg), but Calibrachoa taxawere clearly separated into two groups: (1)C. parviflora andC. pygmaea(1.56 to 1.91 pg); and (2) remaining members of Calibrachoa(2.84to 3.26 pg). Taxa of Petunia sensu Wijsman exhibited largerPI/DAPI ratios (relative fluorescence intensity with PI stainingto that with DAPI staining) than Calibrachoa species exceptC.parviflora and C. pygmaea. This suggests that Petunia sensuWijsman has nuclear DNA with more adenine-thymine rich regionsthan Calibrachoa. Copyright 2000 Annals of Botany Company Calibrachoa, 4',6-diamidino-2-phenylindole (DAPI), flow cytometry, nuclear DNA content,Petunia , PI/DAPI ratio, propidium iodide (PI), Solanaceae     

On mechanisms of removing astringency in persimmon fruits by carbon dioxide treatment I. Some properties of the two processes in the de-astringency

Carbon dioxide treatment of persimmon fruit (Diospyros KakiL., cv. "Hiratanenashi" astringent type) at 20?C for 24 hr,at 30?C for 12 hr, or at 40?C for 6 hr followed by storage inair at 30?C for 3 days produced de-astringent fruit of excellentquality without abnormal softening. The induction process inthe anaerobic atmosphere had a Q₁₀ of ca. 2.0 and the subsequentde-astringency process, which proceeded either in air or carbondioxide, had Q₁₀ of ca. 1.4. During the short gas treatment(at 40?C for 6 hr) the ethanol content increased rapidly andreached a maximum of 28.0 mg and the acetaldehyde content graduallyreached 0.443 mg per fruit, whereas the soluble tannin(s) contentdecreased rapidly to two-thirds of its initial level. Therewas a lag period of 3 hr in the decrease of soluble tannin(s).Dimedon and sodium bisulfite, as well as sodium fluoride, inhibitedde-astringency. The mechanisms of removing astringency in thisfruit are discussed. (Received June 3, 1976; )     

Hormones in Plants Bearing Nitrogen-fixing Root Nodules: Metabolism of [8-14C]Zeatin in Root Nodules of Alnus glutinosa (L.) Gaertn

The metabolism of [8-¹⁴C]zeatin, supplied via micropipettesover a 24 h period to root nodules of Alnus gliutinosa (L.)Gaertn., was investigated. The major metabolites were tentativelyidentified by means of chromatographic, chemical, and enzymictreatments as adenine, adenosine, trans-zeatin riboside, dihydrozeatin,trans-zeatin-O-ß-D-glucoside, and the O-ß-D-glucosideof dihydrozeatin. In addition, a prominent water-soluble peakof radioactivity was present. This did not appear to be a ribosidebut was biologically active in the soybean callus test. The number and nature of the metabolites formed in the noduleswas similar in both dormant and non-dormant plants.     

Growth and Differentiation of Plant Tissue Cultures III. The Initiation and Pattern of Cell Division in Developing Callus Cultures

The factors affecting the initiation and subsequent patternof cell division in the early stages of callus development havebeen investigated using cultured isolated explants from theJerusalem Artichoke (Helianthus tuberosus). The results obtainedhave been interpreted to explain the possible role played byproducts of autolysis in restricting almost all of the celldivisions to the periphery of the tissue. An attempt has alsobeen made to elucidate the factors which may determine the exponentialincrease in cell number which succeeds the initial lag phase.     

Effect of Folate Analogues on the Activity of Dihydrofolate Reductase and Callus Growth of Sunflower

The inhibitory effect of antifolate analogues in vitro and invivo on dihydrofolate reductase and on growth of sunflower callus,was tested. Aminopterin and trimethoprime proved to be the mosteffective inhibitors. The ID₅₀ values for these compounds werethe same as those previously shown for enzymes from rice andcarrot cells. Protein, DNA and RNA synthesis of sunflower callus was inhibitedby the analogues, the inhibition depending on the concentrationused. These results suggest that growth inhibition of sunflowercallus by these analogues is due to inhibition of dihydrofolatereductase. Key words: Antifolate, callus, dihydrofolate reductase, growth, sunflower     

Effect of inhibitors of nucleic acid and protein synthesis on the reappearance of "light interruption rhythm" in a long-day duckweed, Lemna gibba G 3

Effects of several inhibitors of DNA, RNA and protein synthesison the reappearance of a once faded-out light interruption rhythmin a long-day duckweed, Lemna gibba G 3, were studied. The reappearancewas not affected by inhibitors of RNA and protein synthesis;i.e., 2-thiouracil, 8-azaguanine, ethionine and chloramphenicol,but was suppressed by inhibitors of DNA synthesis; i. e., 5-fluorodeoxyuridine,5-fluorouracil and mitomycin C only when these were appliedduring the light period for perturbation. We concluded that synthesis of a new DNA species during thelight period was required for the recurrence of this rhythm. (Received September 25, 1968; )     

Physiological activity of a viridicatin derivative, 3-(4-phenylcarbostyriloxy) acetic acid

A carboxymethylene derivative (V-OCH₂COOH) of viridicatin (V-OH)promoted the root growth of rice and sesame seedlings. V-OCH₂COOHhad no known hormonal activities, per se, but did have an inhibitoryeffect on IAA and 2,4-D-induced growth of Avena coleoptile sectionsand of carrot root callus. However, inhibition by VOCH2COOHof 2,4-D-induced growth in carrot root callus was to some extentreversed by increasing the concentration of 2,4-D. V-OCH₂C0OHseemed to competitively inhibit IAA-induced elongation of Avenacoleoptile sections. (Received September 14, 1970; )