bluuebunny/crossref_metadata_2025 huggingface dataset:
The Importance of Cell Size in the Water Relations of Plants
Authors: CUTLER J. M. , RAINS D. W. , LOOMIS R. S.
Published: April 2006

Several structural changes in cotton (Gossypium hirsutum L.) leaves attendant on development under conditions of water deficit were examined. Cell size was less and cell wall thickness greater in the leaves of stressed plants than in leaves of well‐watered plants. A short review of the literature suggested that the lesser cell size is a fairly general observation and that it may contribute to plant resistance to moisture stress.

A simple model is developed to investigate the influence of the reduction of cell size on cellular water relations. The predictions which can be drawn from simulations with this model are that smaller cells should maintain turgor to lower values of water potential than larger cells. Rather large changes in cell water relations are predicted for small changes in cell size. These effects are related principally to the changing proportion of cell water which resides in the cell wall and is external to the plasmalemma and the osmotic adjustment system. This prediction is in agreement with several observerations on the behavior of stress‐hardened plants and supports the hypothesis that plants or tissues with the smaller cell size will be more tolerant of low water potential.
Rooting Substances in Water Extracts of Castanea sativa and Salix viminalis
Authors: GESTO M. D. V. , VÁZQUEZ A. , VIEITEZ E.
Published: April 2006

The rooting activity of water extracts of cuttings of chestnut (Castanea sativa Mill.) and willow (Salix viminalis L.) was studied throughout the year by the bean rooting test. The chestnut extract nullified the rooting activity of 10−5M IAA, but on the whole it did not modify the rooting pattern of the bean cuttings. The willow extract increased rooting and showed a rhythm in the content of endogenous growth substances. IAA was found at the time when the extract showed the strongest rooting activity. The extract from willow contained two synergistic root‐promoting fractions with the Rf's of 0.0–0.2 and 0.6–0.8 in isopropanol: ammonia: water. The latter one promoted rooting without added IAA. In this fraction a high amount of catechol was detected. No clear correlation was found between the ability to induce roots and the total phenol content in the two species.
Mise en Évidence d'un Effet Régulateur de la Proline Exogène sur le Cycle du Glycolate Chez Nicotiana tabacum cv. Xanthi
Authors: VALLEE J. C. , VANSUYT G. , PREVOST J.
Published: April 2006

Demonstration of a regulatory effect of exogenous proline on the glycolate cycle in Nicotiana tabacum cv. Xanthi n.c.

An exogenous proline supply in the light provokes an increase in free glycine concentration in apical tissues or leaf disks of vegetative Nicotiana tabacum cv. Xanthi n.c. The same phenomenon does not occur in the equivalent tissues of tobacco plants after floral induction, these being naturally rich in proline. Under different environmental conditions (light, dark, varying concentrations of CO2 and O2), the exogenous proline appears to modify one or more reactions of the glycolate pathway.
Change in Electrophoretic Pattern of Ribonuclease during Dormancy and Growth of Bird‐cherry Buds
Authors: EKELUND R. , PERSSON L.
Published: April 2006

Polyacrylamide gel electrophoresis of ribonuclease from buds of bird‐cherry (Prunus padus L.) revealed four different bands (I–IV). The activity of band I, which probably corresponds to an in vivo free ribonuclease, increased from October to January — most rapidly between December, when 69% of the buds were dormant, and January when 43% were in the dormant state — but did not change from January to March, when growth was resumed. Bands II–IV may represent ribonucleases which are structure‐bound in vivo. The activity of band II decreased from October to a minimum in January and then increased from January to March. The activities of bands III and IV were very low from October to February but were enhanced with acceleration of growth in March. The results may indicate that the separate ribonucleases have different functions.
Ethylene Requirement for Germination of Partly After‐ripened Apple Embryo
Authors: KEPCZYNSKI JAN , RUDNICKI RYSZARD M. , KHAN ANWAR A.
Published: April 2006

The effect and involvement of ethylene in germination of partially after‐ripened apple (Malus domestica Borkh. cv. Antonovka) embryos were studied. The requirement of ethylene for germination was shown by the use of a rhizobitoxine analog and 8‐hydroxy‐quinoline sulphate which are inhibitors of ethylene biosynthesis, and by mercuric perchlorate, a trap for endogenously produced ethylene. Excised apple embryos were found to produce progressively greater amounts of ethylene with increasing periods of after‐ripening. Inhibition of germination by rhizobitoxine analog or abscisic acid was accompanied by inhibition of ethylene formation in embryos. Thus ethylene appears to be required for the release of dormancy and germination of apple embryos.
Seasonal Changes in the Cytokinin Content of the Leaves of Salix babylonica
Authors: VAN STADEN J.
Published: April 2006

The young and old leaves of Salix babylonica contain at least four cell division‐inducing compounds which coeluted with zeatin, zeatin riboside and their glucosylated derivatives. During the course of the growing season quantitative changes in the cytokinin content of the leaves were observed. The cytokinin glucosides increased as the leaves aged. The compounds which co‐chromatographed with zeatin and zeatin riboside initially increased until early autumn and then decreased as the leaves senesced. It appears as though the cytokinins transported from the roots are metabolized in the leaves and are converted to their glucosides. Although it has been reported in the literature that Salix root exudate contains very small amounts of cytokinin in late summer and autumn, these compounds increase in the leaves for most of the growing season, suggesting that the leaves may not only obtain cytokinins from the roots but may well be an active site of cytokinin synthesis. It is, however, possible that cytokinins are also transported to the leaves via the phloem, thus accounting for their accumulation in these organs.
Pretreatment of Cell Suspensions as a Method to Increase the Protoplast Yield of Haplopappus gracilis
Authors: WALLIN ANITA , GLIMELIUS KRISTINA , ERIKSSON TAGE
Published: April 2006

A low yield of free protoplasts was obtained when fast‐growing cell suspensions of Haplopappus gracilis were treated with Driselase, an active mixture of cellulase and pectinase. If the cells in the suspension culture were pretreated by increased levels of auxin, reduced sugar concentration, addition of sulphur‐containing amino acids, or by the reducing agent mercaptoethanol, protoplasts were released from a higher proportion of the cells. These pretreatments did not adversely effect division of the protoplasts.
The Effects of Calcium and the Ionophore A23I87 on Modulation, Nitrogen Fixation and Growth of Soybeans
Authors: BLEVINS DALE G. , BARNETT NEAL M. , BOTTINO PAUL J.
Published: April 2006

The calcium ionophore A23187 was used to separate the processes of infection and nodule development from nitrogen fixation in soybeans. Seedlings of Glycine max (L.) Merr. cv. Williams were grown in solution cultures containing three concentrations of Ca2+ (0.1, 0.5 or 1.0 mM) with or without 0.5 μM ionophore A23187. Three weeks after inoculation with Rhizobium japonicum, strain B1. plants were harvested. Low Ca2+ (0.1 mM) significantly reduced nodule number and weight, acetylene reduction, fresh weight of roots and shoots and increased lengths of 2nd and 3rd internodes. There were no significant differences between 0.5 and 1.0 mM Ca2 in their influence on any parameters measured, except for Ca2+ concentration in the tissue. The ionophore A23187 significantly reduced nodule number and weight, and increased internode lengths, but it had no effect on acetylene reduction or fresh weight of roots and tops. The ionophore did not affect the Ca2+ concentration of roots, tops or nodules. Therefore, nitrogen fixation rate is partially independent of number and weight of nodules. The single most important result of this study is that the ionophore A23187 affected critical steps in the infection process or nodule development without influencing subsequent nitrogen fixation.
Effect of Galactose and Other Monosaccharides on IAA Movement in Bean Hypocotyl Segments
Authors: KRUL WILLIAM R. , COLCLASURE G. CRAIG
Published: April 2006

Galactose enhances the production of ethylene gas, and ethylene gas inhibits the movement of IAA in plant tissues. If galactose enhances ethylene production and ethylene inhibits auxin movement, then galactose should inhibit auxin movement. The above hypothesis was examined by observing the effects of d‐galactose, d‐inannose, d‐arabinose, d‐glucose, and d xylose on the uptake, presumed decarboxylation, efflux, velocity and metabolism of labeled indole‐3‐aectic acid in hypocotyl segments of Phaseolus vulgaris L. cv. Pinto. Galactose inhibited, arabinose and glucose enhanced, and mannose and xylose had no effect on partitioning of auxin between tissue and receptor. The reduction of auxin efflux by galactose was related to an increased presumed decarboxylation, reduced uptake and slower velocity of applied auxin. The relationship between galactose‐induced growth effects, ethylene production, and auxin migration are discussed.
The Physiology of the Lichen Peltigera aphthosa, with Special Reference to the Blue‐green Phycobiont (Nostoc sp.)
Authors: ENGLUND BIRGITTA
Published: April 2006

Variations in the morphology and physiology were noted when parts of the Peltigera aphthosa Willd. thallus differing in age were examined. The many small cephalodia on the growing apex of the lichen showed a lower heterocyst frequency (14%) than those on the rest of the thallus (21–22%), which was reflected in the nitrogenase activity. In contrast, highest levels of photosynthesis (14CO2 uptake and O2 evolution) were noted at the growing apex. while respiration rates were fairly stable over the thallus. The water‐holding capacity was greatest in the midparts.

Cephalodial biomass represented an average of 2.6% of total thallus biomass. while the number and size of these structures varied considerably. A minor part of the total carbon fixation (14CO2) and net oxygen evolution (O2 electrode) was performed by the blue‐green phycobiont (Nostoc) in light. A rapid excretion of ammonia from isolated cephalodia was noticed, which together with a comparatively constant C:N ratio throughout the thallus indicated a rapid transport of metabolites facilitated by close physical contact (electron microscopy).
Potassium Absorption by Rice at Different Levels of Organization
Authors: ERDEI LÁSZLÓ , TÓTH ILDIKÓ , ZSOLDOS FERENC
Published: April 2006

The effects of Ca2+ and K+ on the ATPase activities of microsomal fractions prepared from mature roots, cell suspension and callus cultures and redifferentiated roots of rice (Oryza sativa L. cv. Dunghan Shali) exhibit correlations with the effects of Ca2+ on the K+ influx rates. ATPase stimulated by Ca2+ and K+ and the stimulatory effect of Ca2+ on K+ influx are associated in mature roots of low‐salt status. Roots of high‐salt status also possess ATPase of this kind, but K+ influx is depressed by Ca2+. Cell suspension and callus tissue cultures do not possess K+ influx with a positive Ca2+‐response and the ATPase prepared from them is insensitive to the effects of Ca2+ and K+. Redifferentiated roots show similar transport characteristics and enzyme pattern as mature roots of high salt status. The specific transport function of the membrane, and the ATPase stimulated by Ca2+ and K+ are suggested to develop during diffrentiation.
Photosynthetic Capacities and Growth Characteristics of Nicotiana tabacum (cv. Xanthi) Cell Suspension Cultures
Authors: NATO A. , BAZETOUX S. , MATHIEU Y.
Published: April 2006

Photoheterotrophic growth of cell suspensions of Nicotiana tabacum L. (cv. Xanthi) in organic culture medium enriched in sucrose (30 g per liter) showed a classical sigmoid growth curve. The cells developed functional chloroplast structures during the exponential growth phase, when their chlorophyll content increased steadily. A limited drop (30%) in the chlorophyll amount and structural changes of the plastids (starch accumulation) were observed during the lag phase. The measurements of photosynthetic capacities (O2 evolution and CO2 fixation) during the growth cycle revealed changes in the photosynthetic ratio (O2/CO2), which was near 1 during the lag and stationary phases and near 2 during exponential growth. During exponential growth there was also a rapid NO3− uptake. Analysis of label distribution among the products of 14CO2 fixation showed that both CO2 assimilation pathways, linked to the ribulose‐biphosphate carboxylase (the autotrophic pathway) and to phosphoenolpyruvate carboxylase (the non‐autotrophic pathway) were operative with an important increase of the capacity of the latter during the exponential growth phase. Maximum rate of oxygen evolution, either endogenous or with p‐benzoquinone as Hill reagent, as well as the increased CO2 Fixation capacity via the non‐autotrophic pathway during the exponential phase were concomitant with a high cyanide inhibited O2 uptake.
In vitro Organogenesis in Explants from Different Cultivars of Begonia X hiemalis
Authors: WELANDER TORKEL
Published: April 2006

Petiole explants from 17 cultivars of Begonia X hiemalis were grown on a basal agar medium with different combinations of NAA and BA as well as on media lacking microelements or vitamins. The stock plants were kept either under short days (7–8 h of light perday) at 15°C or under long days (15–16 h of light) at 18–21°C. The day length during the in vitro culture was 20 h of light and the temperature 21°C.

Explants from short‐day treated stock plants did not show any differentiation. In explants from long‐day treated stock plants, the percentage of explants with shoot, root and with both shoot and root initiation were recorded after 55 days. Explants forming both shoots and roots were transferred to soil, and plantlet formation was observed after another 55 days. The percentage of explants with organ and plantlet formation differed between cultivars. With increasing NAA and decreasing BA concentrations, the percentage of explants forming only roots increased, whereas the percentage of explants with only shoots decreased. Plantlet formation was most frequent in explants from NAA: BA ratios of 2: 1 and 10: 1, and a variation was found between different cultivars. When the vitamin fraction was not added to the medium, this did not influence formation of shoots, roots and plantlets. When the microelements were omitted. shoots, roots and callus were formed, but no plantlets.
Blue Light‐Induced Phytochrome Increase in Mung Bean Hooks
Authors: TANADA T.
Published: April 2006

An “action spectrum” between 400 and 620 nm for the radiation‐induced phytochrome increase was obtained with mung bean hooks. A broad band between 410 and 480 nm was found to induce significant increases in phytochrome content. Radiation from 500 to 620 nm failed to promote any significant increase. Red irradiation immediately following far‐red treatment showed no reversal. These results and an earlier finding that far‐red irradiation promotes phytochrome increase suggest that the photoreceptor for the radiation‐induced increase is probably not phytochrome, but could be a related pigment if the phenomenon is due to one photoreceptor. The blue light‐induced increase in phytochrome content increases the possibility of the participation of phytochrome in blue light‐mediated high irradiance responses of plants.
The After‐Effect of Water Stress on Transpiration Rate and Changes in Abscisic Acid Content of Young Wheat Plants
Authors: BENGTSON CURT , FALK STIG OLOF , LARSSON STIG
Published: April 2006

Young wheat plants (Triticum aestivum L. cv. Weibulls Starke II) were exposed to water stress for 1, 2 or 3 hours by cooling the roots. The plants were subjected to a constant water stress during the stress periods. By this treatment the leaf water potential was lowered from −6.5 to −11.5 bars. Leaf water potential, transpiration rate and abscisic acid content were determined during the stress periods and during the recovery.

The water stressed plants showed an after‐effect on transpiration rate lasting for between 10 and 24 hours depending on the duration of the stress. The amount of water stress in the stressed plants compared with the controls is defined as the difference in leaf water potential between the controls and the stressed plants during the stress period integrated over time. The amount of after‐affect on transpiration is analogously defined as the difference in transpiration rate between the controls and the stressed plants during the recovery period integrated over time. There was a linear relationship between the amount of water stress and the amount of after‐effect on transpiration of the leaves.

The abscisic acid content of the leaves increased between 3.0 and 4.5 times the original content depending on the duration of the stress. However, during the recovery the abscisic acid content reattained the pre‐stress level within 3 hours for all three stress periods. There was thus no direct relationship between the after‐effect and the abscisic acid content of the leaf.
Effect of Treatments with Growth Retardant Chemicals on Petiole Abscission in Coleus
Authors: SEVERI ALDO , LAUDI GIANNINO
Published: April 2006

A bscission of debladed petioles of Coleus was observed following spray applications of growth retardant chemicals and particularly of Phosfon D to the foliage. Sprays were applied to some branches, which were left intact (inducing branches), or to adjacent branches the leaves of which were later debladed (induced branches). In all experiments two applications of growth retardant chemicals were made, after which the induced branches were debladed. Treatments on induced branches accelerated the petiole abscission relative to the controls. Treatments on inducing branches, instead, decreased abscission speed of debladed petioles. The evidence suggests that phosfon D affects abscission by interfering with the indoleacetic acid mechanism.
Nitrogenase Activity in the Lichen Stereocaulon paschale: Recovery after Dry Storage
Authors: HUSS‐DANELL KERSTIN
Published: April 2006

The effect of prolonged storage on nitrogenase activity in Stereocaulon paschale (L.) Fr. was studied. The thalli had a very low water content during the storage over silica gel at 4°C in the dark. For C2H2‐reduction measurements the lichen samples were remoistened and held at 15°C in the light for 1–36 h before the addition of C2H2. With the longest pre‐incubation time preceding the nitrogenase activity measurements there was no significant decrease in nitrogenase activity during 75 weeks of storage. The method of storage was simple and inexpensive and the nitrogenase activity characteristic of each lichen batch, due to seasonal variation, was well preserved during the storage.
A Comparison of the Endogenous Hormone Levels in Stolons and Sprouts of the Potato Solanum tuberosum
Authors: DIMALLA G. G. , VANSTADEN J. , SMITH A. R.
Published: April 2006

Whereas the gibberellin and inhibitor levels of potato (Solanum tuberosum L. cv. BP‐1) sprouts and stolons differ, their auxin and cytokinin levels apparently remain more or less unchanged. The levels of gibberellin in the sprouts is higher than that of the stolons; however, with regard to inhibitor levels the reverse is true. It would appear as if an internal balance of different hormones controls whether or not tuberization will occur. High gibberellin and low inhibitor levels (sprouts) may favour cell elongation and at the same time limit cell division. Decreased gibberellin and increased inhibitor levels (stolons) seems to favour cell division. As cell division is not retarded despite high inhibitor levels, it would appear as if the effect of the inhibitor is mainly directed at countering the gibberellins.
Uptake of Amino Acids by Barley Leaf Slices: Kinetics, Specificity, and Energetics
Authors: LIEN RAGNVALD , ROGNES SVEN ERIK
Published: April 2006

Uptake of 14C‐labelled L‐lysine. L‐arginine, L‐glutamic acid, L‐aspartic acid, and glycine was studied in 0.75 mm wide barley (Hordeum vulgare L. cv. Lise) leaf slices. After an initial period (10 min) of rapid accumulation amino acid uptake proceeded at a steady, lower rate for several hours. Uptake was stimulated by 10−4M Ca−2+ ions. Uptake was strongly pH dependent with the following optima: aspartic acid pH 3.5. glutamic acid pH 4.1. glycine pH 5.8, lysine pH 6–7, and arginine pH 5–8 (a broad plateau). The optimal temperature was about 30°C. and the temperature coefficient in the range 0–20gGC was 2.3–2.5. Concentration‐dependence data gave uptake isotherms which appeared to be multiphasic for all the amino acids used. The amino acids inhibited each other in a competitive fashion, indicating that they were all transported by a single carrier system. Uptake of lysinc was strongly inhibited by 10−4M 2.4‐dinitrophenol. Lysine uptake was not stimulated by light under aerobic conditions. However, it was much reduced in the dark under anaerobic conditions. This reduction was almost compensated for by light. The light‐stimulation of uptake under anaerobic conditions was abolished by 10−5M 3‐(3,4‐dichlorophenyl) 1.1‐dimethylurea.
Variations among Woody Angiosperms in Response to Flooding
Authors: PEREIRA J. S. , KOZLOWSKI T. T.
Published: April 2006

Effects of flooding on young Populus deltoides, Salix nigra, Eucalyptus camaldulensis, E. globulus, Ulmus americana, Quercus rubra and Fraxinus pennsylvanica plants were studied. Flooding variously induced several sequential physiological disturbances, with stomatal closure among the earliest responses. Subsequent responses included inhibition of root growth, alterations in root and stem morphology, formation of adventitious roots, and leaf senescence. In amphistomatous species (Populus deltoides, Salix nigra, Eucalyptus camaldulensis) flooding rapidly induced stomatal closure on the adaxial leaf surface. It also significantly induced stomatal closure on the abaxial epidermis of Populus deltoides but not that of Salix nigra or Eucalyptus camaldulensis. In hypostomatous species (Eucalyptus globulus, Ulmus americana) flooding significantly induced stomatal closure on the abaxial surface within 3 days. Stomatal responses to flooding were not correlated with leaf water stress. In both long‐ and short‐term experiments, flooding did not significantly increase plant water stress. These results deemphasized the importance of plant water stress in inducing plant responses to flooding. The importance of various hormones in inducing flooding symptoms is discussed.
Atractyloside Inhibition of Adenine Nucleotide Translocation in Mitochondria from Hypocotyls of Vigna sinensis cv. Seridó
Authors: LIMA M. SILVA , DENSLOW N. D. , de MELO D. FERNANDES
Published: April 2006

The translocation of adenine nucleotides into mitochondria isolated from hypocotyls of Vigna sinensis (L.) Savi cv. Serido was examined as a function of oxidative phosphorylation. Mitochondria membrane integrity was assessed by respiratory control and ADP:O ratios.

A kinetic analysis of the translocation of adenosine diphosphate into the mitochondria revealed that the mechanism of translocation obeys classical Michaclis‐Menten kinetics with a Km of 25 μM for adenosine diphosphate. At moderate ratios of atraetyloside to adenosine diphosphate (lower than 0.03), atractyloside appears to be a competitive inhibitor of the translocation process, with a Ki of 0.4 μM. However, non‐linear kinetic parameters are observed with ratios higher than 0.06. A concentration of 2.5 μM atractyloside is sufficient to reduce the translocation of 100 μm ADP by 50%. This represents a higher level of sensitivity to atractyloside than reported for other plants.
Changes in Photosynthetic Activity and Related Processes Following Decapitation in Mulberry Trees
Authors: SATOH M. , KRIEDEMANN P. E. , LOVEYS B. R.
Published: April 2006

Physiological responses to decapitation, in combination with bud removal or bud retention, were followed for 45 days in mature leaves of potted mulberry trees (single shoot with 24 to 28 leaves) held in a greenhouse. Mature leaves, whose photosynthetic activity had already attained a maximum, initially increased and subsequently maintained their rates of gas exchange after decapitation. Equivalent leaves on intact trees showed a gradual decline in photosynthesis together with other changes generally associated with early senescence viz. loss of chlorophyll, increased starch, and accumulation of one category of cytokinin‐like material presumed to be a glucose ester. Maintenance of physiological activity following decapitation, especially when combined with bud removal, was associated with greater chlorophyll content, mesophyll cell enlargement (palisade cells appeared more elongate), lower starch, and alteration in foliar levels of cytokinin‐like substances. Internal constraints on CO2 assimilation, i.e. residual resistance (rr), rather than stomatal factors, appeared to be the major influence on gas exchange. The higher photosynthetic activity of leaves on decapitated trees relative to control trees of the same age was attributed to lower r, but was also associated with higher chlorophyll content (leaf area basis) so that CO2 assimilated per unit chlorophyll was not substantially altered by treatment.
The Water Relations of Pinus sylvestris
Authors: HELLKVIST JERK , PARSBY JAN
Published: April 2006

The water potential (β) in ten‐year‐old Scots pine trees (Pinus sylvestris L.) from four different latitudinal provenances ranging from 57° N to 67° N, growing in close proximity to each other, was measured in a pressure chamber during five selected periods between May 1972 and March 1973. Diurnal and seasonal patterns of φ are presented in relation to irradiance, air temperature and vapour pressure deficit (D) for one cloudy and one clear day in each experimental period.

The largest daily amplitude in φ was found at the beginning and end of summer, indicating a larger resistance to water flow from soil to needles. As the soil water potentials (measured as pre‐dawn values) were, at the same time, the highest for the year, it is suggested that these changes in resistance from period to period mainly take place in the trees.

Plots of φ against D during clear days, showed marked hysteresis as the result of the simultaneous influence on φ of several environmental factors. Close linear relations resulted when φ was plotted against potential evaporation rate (calculated from the Pennman‐Monteith formula). The slopes of these regression lines, essentially the flow resistance, showed marked seasonal variations, with the largest resistance found at the beginning and end of summer.

In most periods the water relations of the trees from different provenances were strikingly similar. A continuous change in the water relations of the remote provenances towards the situation for the “home‐provenance” is indicated by the experimental results. It is concluded that trees from different latitudes after ten years of growth have about the same chance as the home provenance to survive periods during which their water balance might become critical.
The Fate of L‐Tyrosine‐UL−14C in Shoot‐Forming Tobacco Callus
Authors: HASEGAWA PAUL M. , MURASHIGE TOSHIO , MUDD J. BRIAN
Published: April 2006

Tobacco callus fed L‐tyrosine‐UL−14C was sampled at 3‐day intervals for 15 days, homogenized and studied with respect to distribution of incorporated radioactivity. The supernatant obtained by centrifuging of the homogenates at 270 g contained the bulk of the radioactivity although significant activity was also detected in the pellet. Sucrose density gradient centrifugation of the supernatant showed over 90% of the recovered label to be associated with a fraction designated as “less dense than mitochondria”, with the remainder being found in the fraction identified as “mitochondria”. During tissue culture, virtually all of the radioactivity in the fraction “less dense than mitochondria” was recovered in the supernatant obtained by centrifugation at 100,000 g. From 4 to 18% of the labeling in the 100,000 g supernatant fraction was attributable to tyrosine‐containing protein, and the rest to free tyrosine and unidentified anionic constituents. The highest proportions of radio‐activity in the 270 g pellet were associated with substances extractable with NaCl, pronase, 4.6 N NaOH, and acetolyzing reagent. Low but substantial labeling characterized the extracts obtained with Triton X‐100 and 1 N NaOH. The final unextractable residue contained 20% of the 270 g pellet radioactivity.
Effects of Pargyline on Mitochondrial Amine Oxidase Activity, Indoleacetic Acid Synthesis and Growth of Crown‐Gall Tumor Callus
Authors: DAVIES FREDERICK S. , McDANIEL ROBERT G.
Published: April 2006

Vinca rosea L. crown‐gall tumor callus tissue cultures treated with N‐benzyl‐N methyl propargylamine (pargyline) exhibited a decrease in the level of endogenous indoleacetic acid from 0.42 μg/mg of protein to less than 0.30 μg/mg of protein. A simultaneous decrease in the specific activity of mitochondrial amine oxidase from 3000 units to less than 250 units at 1.0 μM, 0.01 mM, 0.1 mM and 1.0 mM pargyline, suggested a relationship between amine oxidase function and indoleacetic acid synthesis. Tryptamine incorporation into indoleacetic acid was also decreased at these concentrations. Pargyline inhibited tumor callus growth significantly (based on fresh weight measurements) at the highest concentration, 1.0mM.

These data support the hypothesis of a coordinate metabolic system linking mitochondrial amine oxidase activity and indole acetic acid synthesis. Inhibitory action of pargyline on the enzyme is reflected in reduced indoleacetic acid levels and, ultimately, in reduced callus growth rates.
Utilization of Photosynthates for Growth, Respiration, and Storage in Tops and Roots of Lolium multiflorum
Authors: HANSEN G. K.
Published: April 2006

Lolium multiflorum L. was grown in pots in controlled environments. CO2‐exchange rates were continuously measured on two pots during 46 and 52 days, respectively, separating between tops and roots. After 20 days, the plants were entirely defoliated and the plants were then followed during the regrowth period. During the experiment, alternating 2–3 day periods of high and low irradiance were applied. Analogously treated plants were frequently harvested to obtain the distribution of assimilates between tops and roots. From integration of CO2‐exchange rates, diurnal photosynthesis and respiration were obtained, and utilization of assimilates was analysed.

The respiration associated with the synthesis of new structural material (growth respiration) was dependent on assimilates originating from both the current and the preceding 24 h diurnal cycles. The amount of new structural material synthesized during the current 24 h diurnal cycle was estimated from the relative contribution of assimilates accumulated from the preceding and the current 24 h and diurnal cycles to growth respiration of the current 24 h. From this approximation, the respiratory components connected to synthesis of new structural material and to maintenance of already established material were found.

Growth and maintenance respirations of the tops were alike during the predefoliation and the regrowth periods. For the roots, however, growth respiration was higher and maintenance respiration lower in the regrowth period. The difference between daily integrated CO2‐exchange and the amount converted into new structural material was assumed to be the daily change in assimilates stored. On the first day of a period of high irradiance, the assimilation per unit leaf weight was higher than on the following day of high irradiance, and an accumulation of storage material took place. On the first day of a period of low irradiance, the assimilation per unit leaf weight was lower than on the following day of low irradiance, and there was a depletion of assimilates stored. These effects were most pronounced during the regrowth period, indicating a change in the metabolic sink demand. This indicates a strong feedback mechanism between sources and sinks, in the sense that accumulation of products will inhibit assimilation.
Localization of Adenyl Cyclase in Meristems of Young Pea Hypocotyls
Authors: HILTON GARY M. , NESIUS KNEELAND K.
Published: April 2006

Electron micrographs of Pisum sativum L. hypocotyl tips treated to localize adenyl cyclase revealed discrete deposits on the internal membranes of cytoplasmic vacuoles which correspond to previously localized enzymes described as acid phosphatases. It remains to be determined whether the specificity of the substrate, adenylyl‐imidodiphosphate, used in the present study is such as to exclude all phosphatase activity other than adenyl cyclase. The acid phosphatase localized in earlier studies by other investigators may be an adenyl cyclase. In the differentiated cells of the root cap, lead precipitate was localized in distinct areas bound to the smooth endoplasmic reticulum.
Ionic Balance of Root‐Shoot Nitrate Transfer in Dwarf Bean
Authors: BRETELER HANS , CATE CHARLOTTE H. HÄNISCH TEN
Published: April 2006

The Dijkshoorn‐Ben Zioni model about potassium recycling in higher plants proposes a stoichiometric coupling between the upward transport of nitrate and potassium, and therefore a 1:1 ratio of these ions in the xylem sap. Phaseolus vulgaris grown in media with different NO3: K+ ratios, however, only rarely showed equimolar concentrations of the two ions in the bleeding sap. Ratios between 0.2 and 11 were observed and the ratios between concentrations of the ions in the exudate and in the external solution were positively correlated. An analysis of the major inorganic constituents of the exudate revealed an ionic balance that requires negligible amounts of charges from organic molecules.
Connection between the Synthesis of Differentiation Specific Proteins and the Capacity of Cells to Respond to Cytokinin in the Moss Funaria
Authors: BOPP MARTIN , ERICHSEN UTA , NESSEL MANFRED , KNOOP BERND
Published: April 2006

The differentiation stage of the caulonema in Funaria hygrometrica protonema is distinguished from the chloronema stage by three additional protein bands (CSP) in the soluble protein fraction. During the change of caulonema to chloronema, which is induced by isolation of single filaments (regeneration), the CSP disappear. This is not the consequence of an accelerated degradation or turnover but of a gradual termination in the de novo synthesis of CSP during regeneration as demonstrated by pulse‐chase experiments with l‐[4,5–3H] leucine. Cytokinin inhibits the termination of the synthesis of CSP. The decrease in synthesis parallels the decrease in ability of the isolated caulonema cells to respond to cytokinin via bud formation. It is therefore concluded that the CSP are involved in the competence of caulonema cells to respond to cytokinins.
A Comparative Anatomical Study of Organogenesis in Cultured Tissues of Maize, Wheat and Oats
Authors: CURE W. W. , MOTT R. L.
Published: April 2006

Five cereals and two related grasses were tested for adventitious shoot production from tissue cultures using methods concordant with those reported to be successful for cereals. The five cereals I wheat (Triticum aestivum L.), oats (Avena sativa L.), and maize (Zea mays L.) Pioneer hybrid 3369A, the Bolivian race Pororo and the Equadorian race Chococenõl were all found to proliferate in culture through an aberrant root‐like mechanism of growth which had the external appearance of callus. Two related species, teosinte (Zea mexicana Reeves and Mangelsdorf) and tripsacum (Tripsacum dactyloides L.), were less successful in culture, but grew in the same way. Oats, and probably Pororo and Chococeño, initiated presumptive shoot meristems directly from root vascular tissues within this root‐like growth. Hybrid maize and wheat initiated no shoot meristems and produced only roots. The occasional shoot production observed in wheat was discounted as simple carryover of existing shoot apices from the primary embryo cultures. This study suggests that the incidence of shoot regeneration in cultures of these cereals may be related more directly to adventitious bud formation on roots than to any controlled de novo organogenesis from undifferentiated callus.
The Effect of Phosphorus and Potassium Deficiencies on Transpiration in Tea (Camellia sinensis)
Authors: NAGARAJAH S. , RATNASURIYA G. B.
Published: April 2006

The effect of phosphorus and potassium deficiencies on transpiration in tea (Camellia sinensis L. Clone DT 1) was studied. The plants were grown in sand culture, and measurements were made after the plants showed phosphorus or potassium deficiency symptoms. The overall growth of plants was reduced by potassium deficiency but not by phosphorus deficiency. Both deficiencies reduced stomatal aperture and increased leaf water potential. Stomatal density decreased in phosphorus deficient leaves and it increased in potassium deficient leaves. The transpiration of whole plants was reduced by both deficiencies. The relative sensitivity of transpiration to water stress was increased by potassium deficiency but not by phosphorus deficiency.
Levels of Growth Regulating Substances during Vernalization of Winter Wheat
Authors: REDA FATMA , LARSEN† POUL , RASMUSSEN OLE S.
Published: April 2006

Seeds of winter wheat (Triticum vulgare L.) cultivars Fema and Ferto, were vernalized at 3°C in the dark. Samples were taken 9, 18, 27, 36 and 45 days after the start of vernalization, and extracts were analysed for auxins, gibberellins and growth inhibiting substances. As vernalization progressed the levels of auxins and gibberellins increased whereas the levels of growth inhibitors decreased. The pattern of growth regulator changes was almost similar in both the cultivars. Vernalization seemingly controls the balance between growth promoting and growth inhibiting substances in winter wheat.
Cytokinin Activity of Benzoylaminodeazapurines, Pentanoylaminodeazapurines and their Corresponding Purine Analogs in Five Bioassays
Authors: MATSUBARA SATOSHI , SUGIYAMA TAMIJI , HASHIZUME TAKESHI
Published: April 2006

Cytokinin activities of 6‐benzoylamino‐1, 6‐benzoylamino‐3‐, 6‐pentanoylamino‐1‐ and 6‐pentanoylamino‐3‐deazapurines and their corresponding purine analogs, 6‐benzoylaminopurine and 6‐pentanoylaminopurine, were examined using five bioassay systems, tobacco callus growth, bud formation on tobacco callus, lettuce seed germination, fresh weight increase of radish cotyledons and retardation of chlorophyll degradation in radish cotyledons. 6‐Benzoylamino‐ and 6‐pentanoylamino‐1‐deazapurines showed stronger cytokinin activity than their corresponding purine analogs in all bioassays used. In tobacco callus growth, 6‐benzoylamino‐1‐deazapurine was nearly as active as zeatin, one of the most active adenylate cytokinins. On the other hand, 6‐benzoylamino‐ and 6‐pentanoylamino‐3‐deazapurines were as active as or less active than corresponding purine analogs.
Effects of Nutrients and Light on Growth and Root Formation in Pisum sativum Cuttings
Authors: ELIASSON LENNART
Published: April 2006

Cuttings obtained from seedlings of Pisum sativum L. were rooted in water solution. Shoot growth continued after excision and shoot length increased considerably before roots emerged. Increase in dry weight was strongly dependent on light supply. Continued growth was dependent on supply of mineral nutrients to the rooting solution.

Mineral nutrients had no or slight influence on the number of roots formed on cuttings from stock plants grown in fertilized soil, but the growth in length of the roots was dependent on the presence of calcium in the solution. Root formation was dependent on photosynthetic products formed after excision. No roots were formed on cuttings kept in the dark. The number of roots increased with increasing irradiance given to the leafy part of the cutting. At a low level of irradiance sucrose supply through the rooting medium increased the number of roots. Light given to the basal part of the cuttings had a strongly inhibitory effect on the number of roots formed. It is concluded that the carbohydrate level easily becomes a limiting factor for root formation in growing pea cuttings. Availability of mineral nutrients influences in the first place the growth of the shoots.
Diurnal and Seasonal Changes in Water Balance of Acer saccharum and Betula papyrifera
Authors: PEREIRA J. S. , KOZLOWSKI T. T.
Published: April 2006

Diurnal and seasonal changes in plant water potential, leaf diffusion resistance, and stem radial changes of Acer saccharum and Betula papyrifera trees were studied in northern Wisconsin during the 1974 and 1975 growing seasons. Water potential decreased during the day, following relatively high values in the morning, and increased in the late afternoon and evening. Diurnal patterns and actual values of water potential varied with species, soil water availability, and factors influencing transpiration (e.g., solar radiation, vapor pressure deficit, and transpiration flux density). When plant water deficits were not severe, leaf resistance of both species was rather stable during the day. During severe droughts, however, leaf resistance increased (stomata closed) during the day when light intensity was high. Leaf resistance at high light intensity was higher in Acer than in Betula. Stomatal closure with decreasing light intensity varied between species and among Acer trees. Tree stems of both species shrank during the day, as internal water deficits developed, and they expanded as trees rehydrated during the night. Stems of Acer shrank more than those of Betula. The amount of daily stem shrinkage increased as the season progressed if the trees were not under severe water deficits. During severe droughts the amount of diurnal stem shrinkage decreased. Shrinkage of stems lagged behind water potential changes by 1 to 2 h in Acer and less than 1 h in Betula. The relationship between stem radius and leaf water potential was not constant throughout the growing season.
Regeneration of Mesophyll Protoplasts Isolated from Dihaploid Clones of Solanum tuberosum
Authors: BINDING H. , NEHLS R. , SCHIEDER O. , SOPORY S. K. , WENZEL G.
Published: April 2006

Protoplasts have been isolated from leaves of shoot cultures of six dihaploid clones of Solanum tuberosum L. (2n = 2x = 24). In the KM medium (Kao and Michayluk 1975), sustained cell divisions were obtained in up to 50% of the plated protoplasts of four clones, whereas only a few divisions occurred in the other two clones. The first mitosis appeared 2–8 days after plating, dependent on the clones. In the clones showing sustained cell divisions, a protoplast titre of about 5 × 103 per ml turned out to be optimal. The culture conditions for protoplasts of one of the poorly growing clones, clone H2 140, have been improved using modified KM media, plating at a concentration of as high as 5 × 104 cells per ml, and subsequent diluting at intervals 5 days. The dilutions were carried out with media containing 0.25% agar. Up to 60% of the plated protoplasts underwent divisions within 10 days under these conditions. After about 15 days, the regenerants were transferred onto media inducing organogenesis. Shoots and roots were formed on modified media MS (Murashige and Skoog 1962) and B5 (Gamborg et al. 1968). Plants have been regenerated in four of the investigated clones. Countings of chromosomes revealed a satisfactory stability of the karyotype in shoot culture and protoplast regeneration.
The Effect of Abscisic Acid (ABA) on the Respiration and Uptake of Inorganic Phosphate by Potato Pith Discs
Authors: HEMBERG TORSTEN
Published: April 2006

Abscisic acid (ABA) stimulates the oxygen uptake and inhibits the uptake of inorganic phosphate of discs of potato pith. It is assumed that ABA acts as an uncoupler of the oxydative phosphorylation in agreement with what was shown earlier for β inhibitor from resting potato peelings. The effect is probably not directly related to growth phenomena.
Cytokinin Activity in Lupinus albus
Authors: DAVEY J. E. , VAN STADEN J.
Published: April 2006

The cytokinin content of the root exudate and leaves of fruiting white lupin plants (Lupinus albus L.) was investigated at 2 weekly intervals after anthesis of the lowest flower on the primary inflorescence. Up to 8 weeks after anthesis the level of cytokinins in the root exudate increased. However, at 10 weeks after anthesis insufficient sap was produced for analysis. Cytokinins co‐eluting with zeatin and zeatin riboside were detected in the root exudate after fractionation on Sephadex LH‐20. The cytokinin levels in the mature leaves steadily increased up to 8 weeks after anthesis and thereafter remained relatively constant. Three peaks of activity, co‐eluting with zeatin, zeatin riboside and the glucoside cytokinins were recorded in the leaf extracts. The level of glucoside cytokinins in the leaves was high at 8 and 10 weeks after anthesis. Paper chromatography of extracts of fruits collected at 2 weeks after anthesis indicated that as fruit development proceeded there was a build up of cytokinin in this region of the plant. It is suggested that, in the white lupin, the cytokinins translocated to the shoot are accumulated in the leaves and in the fruits and that it is only later when there is a considerable decrease in sap (10 weeks after anthesis) production that a decreasing supply of cytokinins leads to shoot senescence.
Cytokinin Activity in Lupinus albus
Authors: DAVEY J. E. , VAN STADEN J.
Published: April 2006

The cytokinins in the pod wall and seeds of the white lupin (Lupinus albus L.) were investigated at 4, 6 and 8 weeks after anthesis. The level of cytokinin in the pod walls increased up to 8 weeks after anthesis, but then declined at 10 weeks. Fractionation on Sephadex LH‐20 shows that during the early stages of pod development cytokinin activity was associated mainly with substances co‐eluting with zeatin and zeatin riboside. However, in the later stages of pod wall growth an increase in activity was noted not only in these cytokinins but also in the cytokinins co‐eluting with the glucoside cytokinins. The level of cytokinin activity in the seeds decreased over the 10‐week experimental period. After fractionation on Sephadex LH‐20 four peaks of cytokinin activity were recorded in extracts of 6‐week‐old seeds. Two of these peaks co‐eluted with zeatin and zeatin riboside. The remaining peaks co‐eluted with the nucleotide and glucoside cytokinins. Only two peaks of activity co‐eluting with zeatin and zeatin riboside on Sephadex LH‐20 were recorded in 10‐week‐old seeds. Dihydrozeatin and its riboside also appear to be present in the seeds extracts. The significance of the quantitative and qualitative changes in the cytokinins of the seeds and pod walls is discussed.