bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Azide on Photophosphorylation in Isolated Spinach Chloroplasts
Authors: HAMLIN LEIF , TILLBERG JAN‐ERIC , SUNDBERG INGRID
Published: April 2006

The influence of sodium azide on open‐chain and flavine mononucleotide mediated cyclic photophosphorylation in isolated spinach chloroplasts was investigated under anaerobic conditions. Open chain phosphorylation was completely inhibited with DCMU both in the presence and absence of sodium azide in the experimental medium. Flavine mononucleotide mediated photophosphorylation was only slightly inhibited by DCMU in the absence of sodium azide but inhibited in two steps by increasing amounts of DCMU when sodium azide was present in the medium. The first step can be explained as being mainly an effect of DCMU on an open chain electron transport, with water and H2O2 as electron donors and with flavine mononucleotide — kept in an oxidized state by sodium azide — as the electron acceptor. The second step, as well as the comparatively insensitivity to DCMU in the absence of sodium azide, depends on cyclic photophosphorylation mediated by flavine mononucleotide.
The Spectral and Photochemical Properties of Subchloroplast Membrane Particles from Pinus silvestris
Authors: ÖQUIST GUNNAR
Published: April 2006

Isolated chloroplasts from Pinus silvestris have been fractionated by a combination of digitonin and Yeda‐press treatment. Different subchloroplast particles have been isolated by differential centrifugation. The spectral and photochemical properties of the different fractions have been analysed. Photosystem I was enriched in the light particles (high Chl a/Chl b ratios, low Chl/P700 ratios, high F735/F685 ratios, high photosystem I activity and enrichment of long‐wavelength absorbing Chl a). The heavy fractions were enriched in photosystem II (low Chl a/Chl b ratios, high Chl/P700 ratios, low F735/F685 ratios and enrichment of short‐wavelength absorbing Chl a). The molar ratio Chl/P700 was about 1.5 times greater for Pinus than for Spinacia, and Pinus had relatively less long‐wavelength absorbing Chl a compared with Spinacia.
Multiphasic Uptake of Ammonium by Soybean Roots
Authors: JOSEPH R. ANTONI , VAN HAI TANG , LAMBERT J.
Published: April 2006

Uptake of ammonium by intact soybean (Glycine max Merr. cv. Amsoy) plants can be represented by 3 phases of a single, multiphasic mechanism in the range 1.78 × 10‐5‐3.57 × 10‐3M. Each phase covers a limited concentration range and obeys Michaelis‐Menten kinetics. The multiphasic pattern of NH4+ uptake is remarkably consistent at all stages of soybean growth (20, 40, 60 and 80 days).
Seasonal Changes in the Effects of Auxin on Rooting in Stem Cuttings of Ficus infectoria
Authors: ANAND V. K. , HEBERLEIN G. T.
Published: April 2006

Ficus infectoria stem cuttings were treated with 10 and 100 μg/ml each of IAA, IBA, 2,4, ‐D and NAA at monthly intervals and planted to study their rooting response after recording morphophysiological status and cambial activty of the parent branches. Attempts were also made to surgically expose the cambium before auxin treatment to determine the relationship of seasonal variation in auxin effectivity to cambial activity. The results show that: (1) there are two distinct phases in the sensitivity of Ficus infectoria stem cuttings to auxin‐induced rooting; (2) the high rooting phase coincides with renovation of growth and high cambial activity starting in March and lasting through August and the low rooting phase coincides with winter dormancy and low cambial activity; (3) roots emerge in longitudinal rows in slitted auxin‐treated cuttings; (4) slitted auxin‐treated cuttings root profusely in June when cambial activity is high but not in October when cambial activity is low suggesting a close correspondence of seasonal variation between the rooting activity of auxin and cambial activity.
Métabolisme du γ‐Aminobutyrate chez Agaricus bisporus
Authors: BALDY PIERRETTE
Published: April 2006

γ‐Aminobutyrate synthesis, the first step in this pathway, is catalysed by L‐glutamate‐1‐carboxy‐lyase (E.G. 4.1.1.15). The purification procedure and some of in vitro properties of this enzyme isolated from fruit‐bodies of Agaricus bisporus 19 Lge were investigated.

Glutamate decarboxylase has been partially purified from a homogenate by a combination of ammonium sulfate fractionation and hydroxylapatite column chromatography. All kinetic studies were carried out manometrically in a nitrogen atmosphere at 35°C by conventional Warburg technique.

The decarboxylase is a pyridoxal‐phosphate requiring enzyme. The pH optimum was found to be between 5.5 and 5.6 and the Km value for glutamate was calculated to be 4 × 10‐2M from a Lineweaver‐Burk plot. Of the amino acids tested the enzyme is specific for glutamate. γ‐Aminobutyrate is not carboxylated to form glutamate. Inhibition by malate, malonate, α‐ketoglutarate and NAD were found to be non‐competitive with respect to glutamate, and those by succinate to be uncompetitive. Fractionation of the subcellular components shows that the enzyme is localized in the hyaloplasm.

The results are discussed in relation to the γ‐aminobutyrate bypath, a probable shunt to the Krebs cycle.
Differential Reactivity in Epidermal Cells of Begonia rex Excised and Grown in vitro
Authors: CHLYAH AVERIL , VAN MARIE TRAN THANH
Published: April 2006

Thin explants composed of the epidermis and underlying collenchyma excised from leaf veins of Begonia rex and cultured in vitro are capable of neoformation of unicellular hairs, roots and buds. Unicellular hairs were formed over the entire surface of the explant when 10−6M indole acetic acid or 10−7M naphthaleneacetic acid (NAA) was added to the basal medium; each epidermal cell was potentially involved. The epidermis was most sensitive to a NAA treatment during the first few days of culture but 30% of the explants could still react after 4 days of culture without NAA. When NAA (5 × 10−7M) and a cytokinin, zeatin (10−7M), were added together, roots were formed from epidermal tissue after numerous divisions in the original cells. Their initiation was not related to particular cells. Buds were formed when a cytokinin (10−6M) was added to the basal medium; bud meristems were formed from small groups of cells surrounding basal cells of glandular hairs. Hair formation was inhibited by either high (32–27°C) or low (12°C) temperatures applied continuously. 32–27°C seemed to inhibit elongation of the hairs specifically, whereas 12°C inhibited earlier phases in hair formation. This hypothesis was supported by short temperature treatments applied at different times during hair formation.
Regulators of Cell Division in Plant Tissues
Authors: GORDON M. E. , LETHAM D. S. , BEEVER J. E.
Published: April 2006

The cytokinins, 6‐benzylaminopurine and kinetin, markedly enhanced the yield of both free and membrane‐bound 80S ribosomes per unit weight of radish (Raphanus sativus) cotyledon tissue. The response was observed only after the induction of growth by cytokinin; during the lag period preceding cytokinin‐induced growth, ribosome yields from both control and cytokinin‐treated cotyledons were below detectable levels. Mannitol depressed both growth and ribosome yield to the same degree. The enhanced ribosome yield appeared to be an indirect effect of cytokinin and was probably a consequence of cytokinin‐induced growth. The effect of 6‐benzylaminopurine on ribosome yield was not reflected in enhanced levels of cytoplasmic ribosomal RNA, while recently synthesized ribosomes were found to be more readily recovered from cytokinin‐treated tissue than from control tissue. It was concluded that cytokinin‐enhanced ribosome yield resulted from enhanced ribosome recovery or extractability and that ribosome yield is an unreliable indication of ribosome level in plant tissue.
Rubidium Absorption by Corn Root Tissue after a Brief Period of Water Stress and during Recovery
Authors: PARRONDO ROLANDO T. , SMITH RICHARD C. , LAZURICK KENNETH
Published: April 2006

Intact and excised samples of corn root tissue were subjected to water stress either by incubation in solutions of osmotica or by desiccation, after which they were transferred to CaSO4 solution for various time periods for recovery. Osmotic agents used were either mannitol or polyethylene glycol 6000 at concentrations adequate to depress rubidium absorption to less than 30% of that of controls. During 6 h following release from osmotic stress, rubidium absorption by samples from intact seedlings treated with mannitol increased to 44% of that of controls, while those treated with polyethylene glycol increased to 79% of that of controls. Recovery of root samples excised prior to stress was very nearly the same as that of samples from intact roots. When water stress was produced by desiccation, recovery was about the same as from polyethylene glycol, attaining a rate of 76% of that of controls after 8 h. Whereas desiccated samples almost completely regained their water content during recovery, none showed correspondingly complete recovery of ion absorption capacity. Finally, during the recovery period, the submerged controls, but not controls in humid air, showed an increase in ion absorption capacity with time, confirming that the widely observed “aging effect” or “washing effect” is due to submersion and not to time per se.
RNA Synthesis in Spring and Winter Wheat during Cold Acclimation
Authors: SARHAN F. , D'AOUST M. J.
Published: April 2006

Marked increases were obtained in the levels of ribosomal and soluble RNA fractions in winter wheat submitted to cold acclimation temperatures. In comparison, the change in the rRNA and sRNA of spring wheat, grown under similar conditions, were less pronounced.

With the cold acclimation treatment, sRNA accumulated by winter wheat shows an important change in its (G + C)/ (A +Ψ+ U) ratio, whereas no change in base composition is observed in the sRNA of spring wheat or the rRNA of both spring and winter wheat.

It is suggested that in winter wheat, cold acclimation temperatures potentiate increased synthesis of specific sRNAs, this possibly being part of the increased capacity for protein synthesis associated with cold acclimation.
The Use of the Pressure Chamber Technique for Measurement of the Water Potential of Transpiring Plant Organs
Authors: MEIRI A. , PLAUT Z. , SHIMSHI D.
Published: April 2006

The existence of water potential gradients in flowering shoots and leaves of roses (Rosa sp., cv. Baccara) and along flag leaves of wheat (Triticum aestivum L.) were studied by means of the Scholander pressure chamber. In roses grown in greenhouse, the water potential measured in transpiring shoots was higher than in leaves detached from these shoots, whereas the potential differences between leaf and shoot after equilibration in the dark were small or negligible. A progressive decrease in water potential was found upon repeated measurement on the same organ; this decline was steeper in leaves than in shoots. Extrapolating this decline to excision time resulted in water potential values which, in transpiring shoots, were 3 to 5 bars higher than in leaves. Detopping the flower bud did not alter this pattern, indicating that the highest water potential in the shoot was in the stem. In field‐grown wheat, the water potential measured in a whole flag leaf was about 6 bars higher than that measured in the apical one‐third of the leaf, and this difference disappeared after equilibrating the detached leaf for 1 h in the dark. These potential differences indicate the presence of resistances along the water path in the organ. The results obtained by the pressure chamber represent the highest water potential in the organ, rather than the average water potential.
Effect of Na+, K+, Mg2+ and ATP on the Relative Electrophoretic Mobility of Sugar Beet Membrane Particles with NaK ATPase Activity
Authors: KARLSSON JAN
Published: April 2006

Electrophoretic measurements on membrane coated particles were performed with a Zytopherometer. Tris‐HCl buffer 0.2 M pH 7.0 at 37°C with addition of different combinations of Na+, K+, Mg2+ and ATP was used as test medium. The membranes were of two types, an untreated preparation with low NaK ATPase activity and a deoxycholate treated preparation with high NaK ATPase activity. There was no marked difference in reaction between the two types of membranes. To both types of membranes Mg2+ gave a strong positive and ATP a slight negative addition to the membrane charge. In the presence of ATP Na+ gave a higher charge contribution than did K+ or a combination of Na+ and K+. This implies that K+ gives a higher affinity for ATP than Na+ does and or that ATP mediates a higher affinity for Na+ than for K+.
Growth Regulators and the Phytochrome‐Mediated Dormancy of Celery Seeds
Authors: THOMAS T. H. , PALEVITCH D. , BIDDINGTON N. L. , AUSTIN R. B.
Published: April 2006

Seeds of five celery (Apium graveolens L.) cultivars germinated at 15°C in the light or dark but at 22°C only in the light. This light requirement was overcome by treatment with a mixture of the gibberellins GA4 and GA7 (GA4/7) but interactions of cytokinins, daminozide, ethephon, EDTA and N‐phenyl‐N′‐4‐pyridylurea (NC5392) with GA4/7 were observed. Varietal differences in response to GA4/7 concentration and the requirement for cytokinins were related to the upper temperature limits for germination of the different cultivars. Seeds of cultivars responding to low concentrations of GA4/7 appeared to contain less natural inhibitor than those requiring either high concentrations of GA4/7 or cytokinin in addition to low GA4/7. The cytokinin requirement for germination was partially removed by leaching the seeds with water. Interaction studies with applied hormones indicated that in seeds incubated in the light inhibition by abscisic acid was partially alleviated by N6‐benzyladenine but not by GA4/7 application. The implications of these results are discussed in relation to the involvement of natural plant hormones in the dormancy mechanism of celery seeds.
Increased Germination Rates of Baldcypress and Pondcypress Seed Following Treatments Affecting the Seed Coat
Authors: MURPHY J. BRAD , STANLEY R. G.
Published: April 2006

The effects of seed‐coat removal, warm‐water soaking, cold stratification, dry‐cold storage and acid treatment on the germination of baldcypress (Taxodium distichum (L.) Rich.) and pondcypress (Taxodium distichum var. nutans (Ait.) Sweet) seed were studied.

Removal of the hard seed coat resulted in a prompt and high percent germination, indicating that there was no physiological embryo dormancy. Cold stratification, warm‐water soaking and acid treatment did not increase percent germination over the control after a 60‐day germination period. They did promote the rate of germination however, having a significantly higher germination at 30 days. Dry‐cold storage promoted the initial rate of germination, but resulted in a decreased percent germination below the control after 60 days.

The above results suggest that moisture, and not cold, was the crucial component of stratification. The improved germination rate following acid treatment further suggests that any treatment which rendered the seed coat more permeable or softened it was more effective in increasing the rate of germination of baldcypress and pondcypress seed.
The Effect of Several Protein Amino Acids and Some Inorganic Nitrogen Sources on the Growth of Sphagnum nemoreum
Authors: SIMOLA LIISA KAARINA
Published: April 2006

The nitrogen metabolism of a bog moss, Sphagnum nemoreum Scop., has been studied in aseptic cultures. The effect of several protein amino acids, especially those found in peat, has been investigated. NH4NO3 (1.25 mM) was the best nitrogen source but NH4+ ions were more effectively utilized than NO3− ions when given as the only nitrogen source. Some of the amino acids (2.5 mM) allowed fairly satisfactory growth (arginine and alanine) when given as the only nitrogen source, but some of them were not utilized at all (leucine, lysine, isoleucine and methionine). Given at low concentrations (0.001 and 0.25 mM) together with NH4NO3 (2.5 mM), most of the protein amino acids failed to reveal any growth‐promoting or ‐inhibiting effect. Only lysine (0.25 mM) clearly inhibited growth under these conditions. The nitrogen metabolism of Sphagnum nemoreum seems to be rather flexible and this species is more tolerant of organic nitrogen, especially hydroxyproline, than the higher plants.
An Evaluation of Some Parameters Required for the Enzymatic Isolation of Cells and Protoplasts with CO2 Fixation Capacity from C3 and C4 Grasses
Authors: HUBER S. C. , EDWARDS G. E.
Published: April 2006

Variable factors affecting the enzymatic isolation of mesophyll protoplasts from Triticum aestivum (wheat), a C3 gras, and mesophyll protoplasts and bundle sheath strands from Digitaria sanguinalis (crabgrass), a C4 grass, have been examined with respect to yields and also photosynthetic capacity after isolation. Preparations with high yields and high photosynthetic capacity were obtained when small transverse leaf segments were incubated in enzyme medium in the light at 30°C, without mechanical shaking and without prior vacuum infiltration. Best results were obtained with an enzyme medium that included 0.5 M sorbitol, 1 mM MgCl2, 1 mM KH2PO4, 2% cellulase and 0.1% pectinase at pH 5.5. In gerneral, leaf age and leaf segment size were important factors, with highest yields and photosynthetic capacities obtained from young leaves cut into segments less than 0.8 mm. To facilitate the cutting of such small segments, a mechanical leaf cutter is described that uniformly (± 0.05 mm) cuts leaf tissue into transverse segments of variable size (0.4–2 mm). Isolations that required more than roughly 4 h gave poor yields with reduced photosynthetic capacity; however, using the optimum conditions described, functional preparations could be roughly 2 h. High rates of light dependent CO2 fixation by the C4 mesophyll protoplasts required the addition of pyruvate and low levels of oxalacetate, while isolated bundle sheath strands and C3 mesophyll protoplasts supported CO2 fixation without added substrates. Rates of CO2 fixation by isolated wheat protoplasts generally exceeded the reported rates of whole leaf photosynthesis. Wheat mesophyll protoplasts and crabgrass bundle sheath strands were stable when stored at 4°C while C4 mesophyll protoplasts were stable when stored at 25°C.
Endogene Jahresperiodik der Blattbewegungen zweier Oxalis‐Arten
Authors: MÜLLER‐HAECKEL AGNES
Published: April 2006

Under natural light‐dark changes at the Arctic Circle special behaviour was observed in the leaf movement of Oxalis regnellii and Oxalis acetosella: (1) Advancing in the beginning of leaf rising. (2) Prolonging of the duration of day position. (3) Increasing positive phase‐andle differences. (4) Prolonging of the duratin of the daily moving‐time. From January to April all these features were running back. The winter behaviour has also been shown in artificial light‐dark changes (12:12), when plants were taken in the trial before mid winter. The reactions did not occur if the plants were put into artificial light conditions after mid winter. Criterions for an endogenous annual periodicity and its possible annual Zeitgebers under natural light‐dark changes are discussed. The positive correlation between the length of day position and the length of day‐time in the summer respectively the length of night‐time in the winter, as well as positive phase‐angle difference in spring and in autumn/winter, are judged as a criterion for a second oscillator.
Effect of Oxidized Nucleotide Coenzymes and Mercaptoethanol on Stabilization of Plant Dehydrogenase Activity in Crude Extracts
Authors: HAISSING BRUCE E. , SCHIPPER ARTHUR L.
Published: April 2006

Activity loss of 6‐phosphogluconate, glucose‐6‐phosphate, and glyceraldehyde‐3‐phosphate dehydrogenases occurs in crude plant extracts prepared with insoluble polyvinylpyrrolidone (PVP) and a reducing agent, such as mercaptoethanol. Oxidized nucleotide coenzymes (1 mM), in addition to mercaptoethanol (100 mM), in the extraction buffer stabilizes activity of these dehydrogenases in extracts from both woody and herbaceous plants. PVP and mercaptoethanol alone equally stabilize malate dehydrogenase from most species tested. The mercaptoethanol and coenzyme treatment has proven useful in quantification, purification, and characterization of dehydrogenases in physiological investigations.
Properties of (Sodium Potassium)‐Stimulated ATPases in English Ryegrass Roots and Implications in Ion Transport
Authors: NELSON P. V. , KUIPER P. J. C.
Published: April 2006

Maximum ATPase activities in the cell wall fraction of English ryegrass (Lolium perenne L.) roots were stimulated by foru discrete millimole ratios of (Na++ K+); 40:0, 35:5, 5:35, and 0:40. The optimal pH for stimlation was found to be 6.5. Contrary to data in the literature, Mg2+ inhibited all stimulatory ratios of (Na++ K+) when plants were cultured on an adequate nutrient solution. When grown on a dilute solution, Mg2+ enhanced (Na++ K+)‐stimulated ATPase activity in this membrane preparation. The single optimal combined concentration of (Na++ K+) for all stimulatory ratios was 40 MM. The ratios of (Na++ K+) which stimulated ATPase activity in the cell wall fraction varied with position along the root axis such that all rarely existed simultaneously nor did any exist in the terminal millimetre of the root. Both cell wall and microsomal fractions showed stimulation by (Na++ K+) at all the above ratios indicating the possible presence of plasma membrane fragments in both fractions. Only the 35:5 ratio was stimulations were found in the supernatant. Implications of ion‐stimulated ATPase involvement in ion transport were drawn from the appearance of ATPase activity at a 40:0 ratio of (Na++ K+) and the disappearance of stimulations at 35:5, 5:35, and 0:40 ratios when plants were moved from a strong (35 mM total concentration) to a dilute (0.75 mM) nutrient solution.
Comparative Study of β‐Glucosidase from Cotyledons and Fruits of Cucumber, Cucumis sativus
Authors: McCREIGHT J. D. , PHARR D. M. , LOWER R. L. , SOX H. N.
Published: April 2006

This study was conducted to compare the β‐glucosidase of cotyledons and fruits of Cucumis sativus L. cv. Chipper. The concentration of the enzyme was followed throughout the growth period of each organ. The greatest concentration of the enzyme did not correspond with the most rapid period of growth. Each enzyme was characterized kinetically. The Michaelis constant of the cotyledon β‐glucosidase for p‐NO2‐phenyl‐β‐D‐gluco‐pyranoside was 1.57 mM, and was 0.35 mM for the fruit enzyme. The enzymes from the two sources also differed in affinity for glucono‐1,5‐lactone, a competitive inhibitor of β‐glucosidases, susceptibility to inhibition by saccharides, and heat stability. The two organs apparently contain different forms of β‐glucosidase.
Changes in Chloroplast Lipids during the Development of Photosynthetic Activity in Barley Etio‐Chloroplasts
Authors: SELLDÉN GUN , SELSTAM EVA
Published: April 2006

The content of monogalactosyl diglyceride, digalactosyl diglyceride, sulfoquinovosyl diglyceride and phosphatidyl glycerol of gel‐filtrated etio‐chloroplasts isolated from greening barley seedlings was determined. The development of photosynthetic electron transport, measured as anthraquinone autooxidation, was simultaneously determined with an oxygen electrode.

During the first hour of irradiation of the etiolated seedlings the lipid content of the plastids decreased rapidly. The decrease is interpreted as a chlorophyll sensitized photooxidation of the fatty acids of the diglycerides.

With artificial electron donors an oxygen uptake was detected after 10 min of greening. With no donors added, a DCMU sensitive oxygen uptake was detected after 2 h. The level of DCMU inhibition increased as the plastid developed and total inhibition was obtained after 5 h.

Between 2 and 6 h of greening the lipid content of the plastids stayed constant. During this greening period there was a correlation between the appearance of a DCMU sensitive electron transport and the accumulation of the trans‐3‐hexadecenoic acid of phosphatidyl glycerol. The trans‐3‐hexadecenoic acid was present already in the dark‐grown seedlings but an increase in content did not occur until after 3 h.

The lipid content increased after 6 h of greening. This increase coincided well in time with the formation of grana. The fatty acid composition of the individual lipids, with the exception of phosphatidyl glycerol, and the monogalactosyl diglyceride to digalactosyl diglyceride ratios did not change fundamentally during the greening.
Étude des activités photochimiques des étiochloroplastes isolés de plantules verdies en lumière intermittente
Authors: MATHIEU YVES
Published: April 2006

Photochemical Activities of Etiochloroplasts Isolated from Plants Greened under Intermittent Light. I. Absorption of Oxygen.

Oxygen exchange by isolated etiochloroplasts from wheat leaves (Triticum sativum Lam. cv. Florence Aurore) has been studied with an oxygen electrode. The etiochloroplasts lack an oxygen evolving mechanism and show a light induced oxygen uptake with two components. One component, sensitive to 3‐(4‐chlorophenyl)‐1,1‐dimethylurea, results from electron flow through an active photosystem II and is suppressed by photosystem II electron donors. The other component is inhibited by quinones suggesting that it might represent some mechanism to trap and dissipate excitation energy from chlorophyll in competition with that produced by the presence of artificial traps. The results are discussed in order to explain the apparent lack of coupling between photosystem II, through which some electron flow is operating, and the active photosystem I present in these plastids.
Étude des activités photochimiques des étiochloroplastes isolés de plantules verdies en lumière intermittente
Authors: MATHIEU YVES
Published: April 2006

Photochemical Activities of Etiochloroplasts Isolated from Plants Greened under Intermittent Light. II. Photobleaching of Pigments.

Etiochloroplasts were isolated from wheat leaves (Triticum sativum Lam. cv. Florence Aurore) greened under repeated flashes with intervals of 15 min of darkness. These plastids are unable to evolve oxygen and show a light‐induced bleaching of chlorophyll and carotenoids. This bleaching is inhibited by 3‐(4‐chlorophenyl)‐1,1‐dimethylurea and partially results from the presence of an active photosystem II.

Pigment stabilization can be achieved after giving additional repeated flashes with short intervals of darkness (5 s) to the seedlings; but stabilization is then much lower than that obtained by continuous light when plastids with similar photochemical activity (Hill reaction) are compared.

Pigment bleaching in etiochloroplasts is thus not only due to their inability to use water as photosystem II electron donor but results also from other structural or functional deficiencies.
The Potassium Requirement for Growth and Embryogenesis in Wild Carrot Suspension Cultures
Authors: BROWN SUSAN , WETHERELL DONALD F. , DOUGALL DONALD K.
Published: April 2006

A requirement for potassium for growth and forembryogenesis in suspension cultures of wild carrot (Daucus carota L.) was demonstrated. The concentration of K+ required for maximal growth (1 mM) was less than that required for maximal embryogenesis (20 mM). Neither Na+ nor NH4+ could replace K+. Ammonium ion enhanced embryogenesis when K+ was present at suboptimal levels greater than 1 mM. Nitrogen sources strongly influenced growth and embryogenesis, but the effects of nitrogen were separable from those of K+. Subline differences were noted. Subline CSC‐29 produced nearly half the maximum embryo number in 1 mM K+ while CSC‐31 produced no embryos at that K+ concentration. Growth of CSC‐29 was slightly repressed by Na+, but no more than by similarconcentrations of K+. Growth of CSC‐31 in 1 mM K+ was strongly repressed by Na+. Embryogenesis in CSC‐29 was unaffected by Na+. In CSC‐31, Na+ repressed embryogenesis at lower concentrations of K+.
Anthurium andraeanum Plantlets Produced from Callus Tissues Cultivated in vitro
Authors: PIERIK R. L. M.
Published: April 2006

During the last 3 years a method has been developed to reproduce Anthurium andraeanum Lind. through callus cultures. The procedural sequence is as follows: callus induction on excised leaf fragments, callus subculture on solid and in liquid media, adventitious sprout formation in callus on solid media, and rooting of excised sprouts. Recently 20 adult genotypes were propagated by this method.
The Inhibitory Action of Cycloheximide on Respiration of Coleoptiles is Relieved by Light
Authors: DHEIDAH M. , BLACK M.
Published: April 2006

Concentrations of cycloheximide which are frequently used for the specific purpose of inhibiting protein synthesis also reduce oxygen uptake in Triticum and Avena coleoptiles in darkness by up to 50%. Except at high concentrations of the chemical diffuse daylight almost completely relieves this inhibitory effect provided the coleoptiles are not submerged. In darkness oxygen consumption is rapidly affected when cycloheximide is supplied to coleoptiles; the relief by light is also fast. These observations raise questions concerning the use of cycloheximide in studies with coleoptiles.
Photochromic Pigments from Blue‐Green Algae: Phycochromes a, b, and c
Authors: BJÖRN G. S. , BJÖRN L. O.
Published: April 2006

Aqueous extracts of blue‐green algae were fractionated by electrofocusing. In all algae investigated, fractions with iso‐electric points at or near 4.6 showed photochromic behaviour analogous to that of phytochrome, although they were sensitive to light of shorter wavelength. Three main types of photochromic pigments were found: Phycochrome a (in Tolypothrix distorta, Phormidium luridum, Nostoc muscorum 1453/12, and Anacystis nidulans) has one form absorbing maximally at about 590 nm (formed under red light) and one absorbing maximally at about 630 nm (formed under green light). Phycochrome b (in Tolypothrix distorta) has one form absorbing maximally near 510 nm and one form absorbing maximally at 570 nm (formed in yellow‐green and blue‐green light, respectively). Phycochrome c (in Nostoc muscorum A and probably in Tolypothrix tenuis) has one form absorbing maximally at 650 nm (formed under green light) and one absorbing very weakly in the green region (formed under red light). The conversion of Phormidium phycochrome a from its red‐absorbing form to its green‐absorbing form causes the same spectral change as if an f‐chromophore of phycocyanin were transformed into an s‐chromophore. The quantum yield for this conversion is estimated to be 0.1, while the quantum yield for the reversion is estimated to be 0.4 on the assumption that the absorption coefficients are those of f‐ and s‐chromophores. Phycochrome c is less light‐sensitive than phycochromes a and b.
Light‐Induced Absorption Changes in Etiolated Coleoptiles
Authors: WIDELL S. , BJÖRN L. O.
Published: April 2006

Blue (or green) light induced reversible and irreversible absorption changes in etiolated wheat (Triticum aestivum) coleoptiles. Immediately after a 10 s pulse of blue light there was an absorbance increase at 440 nm and a decrease at 420 nm. The absorbance at 440 nm returned to the original level in a biphasic way, with first‐order rate constants of 0.05 s−1 and 0.006 s−1 at 25°C. The change at 440 nm was partly, but not completely, inhibited by iodide. In the 500–600 nm region complex changes occurred, indicating the participation of at least two different cytochromes, one of which was oxidized during a 10 s light pulse and the other oxidized more slowly during the following dark period.
Seed Germination and Bolting in Red Beet as Affected by Parent Plant Environment
Authors: HEIDE OLA M. , JUNTTILA OLAVI , SAMUELSEN RAGNAR T.
Published: April 2006

Low temperature and long day regimes applied during seed development and maturation of red beet (Beta rulgaris var. rubra L.) increased the proportion of empty seed balls and reduced the germination ability of normally developed seeds. Low seed development temperatures also greatly increased the bolting susceptibility of seedlings grown at low temperatures or temperatures which are marginal for bolting, but were not able to bring about bolting under conditions which are not themselves inducive to flowering. In a field experiment a significant reduction of the root tuber yield was associated with these effects.
The Influence of 8‐Hydroxyquinoline on the Accumulation of Porphyrins in Dark‐Grown Wheat Leaves Treated with δ‐Aminolevulinic Acid
Authors: RYBERG MARGARETA , SUNDQVIST CHRISTER
Published: April 2006

Dark‐grown wheat leaves treated with δ‐aminolevulinic acid and 8‐hydroxyquinoline accumulated porphyrins, most of which were protochlorophyllide and magnesiumprotoporphyrin monomethylester. The ratio between these two components was dependent on the concentration of 8‐hydroxyquinoline. Small amounts of other porphyrins could also be detected. The treatment with 8‐hydroxyquinoline and the presence of large amounts of porphyrins other than protochlorophyllide did not influence the photoreduction of protochlorophyllide or the Shibata shift. 8‐Hydroxyquinoline caused an inhibition of protochlorophyllide biosynthesis, which could be reversed by rinsing the leaves several times with phosphate buffer. Magnesiumprotoporphyrin monomethylester was then converted to protochlorophyllide. The reversal induced by washing was increased if the buffer contained iron. The possible function of iron in the chlorophyll metabolism and its role in the inhibition reactions with 8‐hydroxyquinoline are discussed.
Gibberellin and Inhibitor Content during Iris Bulb Development
Authors: ALPI A. , CECCARELLI N. , TOGNONI F. , GREGORINI G.
Published: April 2006

Concentrations of gibberellin‐like substances and inhibitors were determined in different organs from Iris hollandica cv. Prof. Blaauw during cold treatment and during growth in the greenhouse. Barley‐aleurone, dwarf pea and Avena coleoptile straight growth bioassays were used to determine the activity. Developing bulblets contained the highest level of gibberellin activity followed by that in floral organs. During the development of the plants quantitative changes occurred both in the non‐acidic, free, and bound pools of gibberellins.

Two kinds of inhibitors, “acidic” and “non‐acidic”, have been found in the extracts. Most of the non‐acidic type were present in the roots. The acidic inhibitors were present in scales and sheath‐leaves and disappeared with cold treatment.
Glumatic‐Oxaloacetic Transaminase in Leaves of Phosphorus‐Deficient Citrus Plants
Authors: ACHITUV MIRIAM , BAR‐AKIVA A.
Published: April 2006

Phosphorus deficiency in citrus leaves resulted in reduced glutamic‐oxaloacetic transaminase (GOT) activity and low pyridoxal‐phosphate (PLP) content. GOT activity was estimated in crude enzyme extracts by spectrophotometry PLP content was detected colorimetrically in water‐alcoholic extracts.

K and Cu deficiencies increased; ‐N, ‐S and ‐Zn decreased and ‐Mg, ‐Fe and ‐Mn did not affect GOT activity in citrus leaves.

Experiments were conducted to restore enzyme activity either by direct addition of PLP to the reaction mixture or by infiltration of PLP or KH2PO4 to detached, intact leaves. The infiltration was carried out in vacuo and the leaves were incubated on wet paper for 26 h, after which enzyme activity was estimated. Transamination activity of ‐P leaves more restored by PLP than by KH2PO4 treatments. In zinc‐deficient leaves the enzyme activity was not restored by infiltration of KH2PO4.
Allelopathic Inhibitors in Seeds of Hevacleum laciniatum
Authors: JUNTTILA OLAVI
Published: April 2006

Biological inhibitors present in the dry seeds of Heracleum laciniatum Horn have been studied by means of thin layer chromatography and various bioassays. The ethylacetate fraction of methanol extracts contained three main groups of inhibitors having the following R values when chromatographed on silica gel with chloroform: (1) 0.60–0.80; (2) 0.20–0.40; (3) 0.0–0.10.

The group (1) inhibited lettuce seed germination and root growth, elongation of Avena first internode segments, growth of the fungus Cladosporium cucumerinum, and it caused leakage of betacyanin from red beet tuber slices. The groups (2) and (3) had no activity in red beet betacyanin leakage test, but they were inhibitory in the other bioassays used. The group (3) were generally less active than the group (2). The group (2) contained the furanocoumarins pimpinellin, bergapten, isobergapten and angelicin. Inhibitors present in the groups (1) and (3) have not been identified. Effects of five synthetic furanocoumarins (pimpinellin, bergapten, isobergapten, isopimpinellin, sphondin) on lettuce seed germination and Cladosporium growth were investigated. Pimpinellin was inhibitory to Cladosporium growth, and lettuce seed germination was inhibited by pimpinellin and sphondin.
Simultaneous Appearance of C‐550 and Cytochrome b559HP (High Potential Form) in Barley Leaves Greened under Intermittent Light
Authors: FARINEAU JACK
Published: April 2006

Cytochrome b559HP has been detected by spectrochemical assays in plastids of barley leaves greened under intermittent light (flashed leaves). The amount of cytochrome b559HP in these plastids was nearly 10‐fold lower than in normal chloroplasts when the results were expressed on plastid number. The amount of cytochrome b559HP phototransformable at ‐170°C was similar, on a C‐550 basis, in the plastids of flashed and normal green leaves. The appearance of the 2 components was simultaneous during the greening process under intermittent light and it is suggested that it was parallel to the increase of appressed regions in thylakoids.

The illumination of flashed leaves under continuous light for 5 minutes allowed the appearance of a normal Photosystem‐II activity, but had no effect either on the cytochrome b559HP content of the plastids or on the photoreactivity of this component at low temperature.
Wachstum und N‐Stoffwechsel sowie Anderungen des Isoenzymspektrums der Glutamatdehydrogenase (GDH) in batchvermehrten, licht‐ und dunkelkultivierten Zellsuspensionen von Pisum sativum
Authors: PRIESS H. HARMS. I. , PAHLICH E.
Published: April 2006

Growth, N‐metabolism and isoenzyme pattern of glutamate dehydrogenase in batch‐cultures of Pisum sativum cells under light and dark conditions.

Cell suspension cultures of Pisum sativum L. derived from root and shoot sections of seedlings have been prepared and cultured in defined nutrient medium. Both the cells and the media were analysed daily for the N‐fractions and carbohydrates during the growth period.

The data obtained indicate specific correlations between growth and nitrogen and carbohydrate metabolism. At the beginning of the growth cycle ammonia as compared to nitrate was favoured in uptake. An increased uptake of nitrate occurred at the end of the linear growth phase when carbohydrate in the media was depleted. The uptake of sucrose was rapid during the whole growth cycle, only in the range of the linear growth phase the uptake stagnated for 3 or 4 days. During increased biosynthesis of nitrogenous compounds at the beginning of the growth cycle up to seven isoenzymes of the glutamate dehydrogenase could be separated by polyacrylamide gel electrophoresis. The isoenzyme pattern changed during the stationary growth phase, especially when the carbohydrate content in the medium decreased. There is some evidence that the isoenzyme pattern is influenced by carbohydrate metabolism.
Extracellular Alkaline Phosphatase in Multicellular Marine Algae and Their Utilization of Glycerophosphate
Authors: WALTHER KRISTINA , FRIES LISBETH
Published: April 2006

The production of extracellular alkaline phosphatase by multicellular marine algae in axenic culture has been investigated. The algae studied were five species of Rhodophyta: Asterocytis ramosa, Goniotrichum elegans, Nemalion helminthoides, Polysiphonia urceolata and Rhodosorus marinus; and one species of Phaeophyta: Ecrocarpus confervoides. The extent of enzyme activity varies from one species to another. It also varies with the phosphorus conditions under which the alga is grown. The pattern of glycerophosphate utilization suggests that this type of compound is not taken up directly by the alga but split by the external enzyme before uptake of the phosphate‐ion only. The enzyme performs its action outside the organism and appears both associated with the cells and free in the surrounding water. Assays with culture filtrate of Asterocytis and Ectocarpus show that the enzyme is an unspecific phosphomonoesterase with optimum activity far to the alkaline side. It is activated by Zn2+.
Acetylcholine and Synthesis of Ethylene in Etiolated Bean Tissues
Authors: PARUPS E. V.
Published: April 2006

Acetylcholine chloride inhibited ethylene production in etiolated bean tissues and prevented to some extent the IAA‐promoted opening of the bean hypocotyl hooks. The results were interpreted on the basis of acetylcholine mimicking the effects of red light on auxin content and ethylene production.
Changes in the Reactivity of the Photosynthetic Apparatus in Heterotrophic Ageing Cultures of Scenedesmus obliquus
Authors: KULANDAIVELU G. , SENGER H.
Published: April 2006

Dark grown cultures of Scenedesmus aged for 2, 10 and 30 days, when transferred into light for 2 hours showed about 1.5, 10 and 80 fold increases, respectively, of their oxygen evolving capacity. The presence of Mg2+ and Mn2+ accelerated the reactivation; neither cell growth nor cell division was apparent during reactivation. An action spectrum for this reactivation process showed essentially the same absorption spectrum of that of chlorophyll in vivo which indicates the energy dependence of the process on photosynthesis. Kinetics of cytochrome f photo‐oxidation, 520 nm absorbance changes and fluorescence induction demonstrate that the immediate recovery of the photosynthetic capacity is mainly due to a reestablishment of a balanced electron transport system. Light periods as short as 30 minutes were found to be sufficient to reestablish an efficient coupling between the two photosystems.
Effect of Lincocin Treatment on the Greening Process in Bean (Phaseolus vulgaris) Leaves
Authors: SÁRVÁRI ÉVA , HALÁSZ G. , NYITRAI P. , LÁNG F.
Published: April 2006

The effect of lincocin (a plastid protein synthesis inhibitor) treatment on the greening process of bean (Phaseolus vulgaris L.) leaves have been studied.

In comparison with control leaves treated ones had a decreased rate of chloroplast development. They had a marked chlorophyll deficiency and a decreased chlorophyll a/b ratio. Some long and short wavelength forms of chlorophyll a were lacking as evidenced from the absorption spectra at 25°C and the fluorescence spectra at 77°K. The –14CO2 fixation was inhibited by 80–90% in treated leaves. The fluorescence induced by the measuring light was greater in the treated leaves than in the control ones, and the kinetics of the decline of the relative fluorescence intensity were also different. Electron microscopic studies showed macrogranum‐like structures and incomplete membrane vesicles in the treated plastids. After longer treatment a destruction of membranes was observed.

The results indicate some structural and functional membrane deficiencies and instability of the membranes.
Mineral Nutrition and Morphine Production in Papaver somniferum
Authors: COSTES C. , MILHET Y. , CANDILLON C. , MAGNIER G.
Published: April 2006

Mineral nutrition of poppy (Paparer somniferum L.) was studied in its effects on morphine production. Hydroponic cultures were carried out with nutritive solutions percolating over sand.

The anion NO3‐ is the most efficient form of nitrogen for the production of fresh matter, dry matter or total morphine; in the latter respect, it rates higher than the NH4NO3 form which, on the other hand, gives higher alkaloid contents, while both cation NH4+ and urea have depressive effects.

Phosphates have apparently little effect on the growth of the poppy, but solutions enriched with assimilable phosphate do stimulate flower proliferation and fruit development, without increasing markedly the total morphine output.

Mg2+ and Ca2+ are important factors; Mg deficiencies will bring about a marked elongation of stems and early flowering, without any notable decrease in morphine outputs; conversely, Ca deficiencies will cause a drop in alkaloid production, while more calcium in the solution will give stronger elongation, a larger number of capsules and a marked increase in the weight of dry matter and morphine outputs, without any marked change in content.

Sodium will favour poppy development (flowers and capsules) and will increase both the content and output of morphine. Na+ should therefore be introduced whenever possible in the fertilizing of poppy crops.
Chemical Forms of Manganese and Zinc in Phloem Exudates
Authors: VAN GOOR B. J. , WIERSMA D.
Published: April 2006

Investigations were performed to study the chemical form in which manganese and zinc are transported in sieve tubes. As a test plant Ricinus communis was used. From this plant phloem sap can be obtained in a rather pure state. The plants received labelled manganese or zinc. In the experiments on manganese translocation a radioactive phosphorus isotope was added to the nutrient solution to test if complex compounds of the cation contain also phosphorus. Components of the phloem exudate were determined by means of physicochemical separation methods.

Almost all zinc but only a part of the manganese were bound to organic compounds. The major part of the manganese was in ionic form. The molecular weight of the complexing com‐pound(s) of manganese was estimated to be between 1000 and 5000 and of zinc between 1000 and 1500. The complexes probably contain some phosphorus. The charge of the zinc complex is negative.
Adaptation to Water Stress in Wheat
Authors: SIMMELSGAARD S. E.
Published: April 2006

Three experiments were designed to investigate to what extent adaptation to water stress take place. Wheat (Triticum aestivum L. cv. Kolibri) was grown in water culture at constant temperature, air humidity, and light intensity. When the plants were 16 days old, the potential of the root medium (ψr) was lowered by 1 bar every second day by means of polyethyleneglycol 1500 down to −4 or −7 bar and then remained at these levels. As a control one experiment was grown at −0.7 bar. By regression it was found that when ψr was lowered by I bar, osmotic potential in leaf (ψπ) decreased 1.46 bar, and leaf water potential (ψt) 0.68 bar, which mean an increase of turgor of 0.78 bar. At the same time the leaf water content did fall 0.30 g per g dry matter. Specific transpiration rate increased significantly after ψr was kept constant, but the increase in area of fresh leaves was strongly reduced due to wilting of old leaves.

After an “adaptation” period during which ψr remained at −0.7, −4, and −7 bar, respectively, for at least 1 week. ψr was altered so as to cover the range from 0 to −14 bar and ψπ, ψr, transpiration and diffusion resistance in stomata (rs) were measured. The levels of ψπ and ψ1 were lower (more negative) and turgor potential higher in plants grown at low ψr. The transpiration in pre‐stressed plants showed less sensitivity to the alteration of ψr than in the non‐stressed plants. The values of ψr at which rs increased greatly, were found to be about −13, −15, and −18 bar for plants grown at −0.7, −4, and −7 bar, respectively.
Mechanism of Action of the Herbicide 2‐Chloro‐3(4‐chlorophenyl) Propionate and its Methyl Ester: Interaction with Cell Responses Mediated by Auxin
Authors: ANDREEV G. K. , AMRHEIN N.
Published: April 2006

Chlorfenprop‐methyl (the herbicidal component of BIDISIN®), and to a lesser extent the free acid, chlorfenprop, inhibit auxin mediated cell responses in coleoptiles of Avena sativa L. and Zea mays L., such as cell elongation, auxin‐uptake, ‐transport and ‐metabolism, acidification of growth media, and binding of naphthyl‐I‐acetic acid to auxin‐specific binding sites in homo‐genates of corn coleoptiles. Within a very narrow concentration range (1 to 2μM) chlorfenprop‐methyl arrests growth from 0 to 100% in sensitive cultivars. The compound displays neither auxin‐nor anti‐auxin‐activity, and only the l(—)‐enantiomer is active. The interaction of the herbicide with auxin at the level of membranes is proposed.