bluuebunny/crossref_metadata_2025 huggingface dataset:
Respiration and NADH‐Oxidation of the Roots of Flood‐Tolerant and Flood‐Intolerant Senecio Species as Affected by Anaerobiosis
Authors: LAMBERS HANS
Published: April 2006

Respiration was measured under anaerobiosis in the roots of two Senecio species: S. aquaticus Hill, which is flood‐tolerant, and S. jacobaea L., which is flood‐intolerant. NADH‐oxidation under anaerobiosis was measured in roots of S. aquaticus, S. jacobaea and S. vulgaris L., which is also flood‐intolerant.

Protein content of S. aquaticus was about 15% higher under anaerobiosis. At 20°C respiration of the roots of S. aquaticus was 50% inhibited under anaerobiosis, while an almost complete inhibition occurred in the roots of S. jacobaea. The activities of nitrate reductase, glutamate dehydrogenase and lactate dehydrogenase were considerably higher in the roots of S. aquaticus grown under anaerobic conditions than in roots grown under aerobic conditions. In S. jacobaea glutamate dehydrogenase activity was lower and in S. vulgaris nitrate reductase was lower and glutamate dehydrogenase activity was higher in roots grown under anaerobic conditions. The possible role of these enzymes for metabolism under anaerobic conditions by oxidizing a surplus of NADH is discussed.

Since oxidative phosphorylation is 50% inhibited under anaerobiosis, ATP has to be generated in a different way. It is argued that maintenance of the ATP‐level may be compensated by way of the enzymes mentioned above, in combination with a modified glucose utilization.
Effects of Ethylene and 2,4‐D on the Activity of Cellulase Isoenzymes in Abscission Zones of the Developing Orange Fruit
Authors: GOREN R. , HUBERMAN M.
Published: April 2006

The role of ethylene and 2,4‐D in the abscission process, and the induction of cellulase isoenzymes in the abscission zones of Citrus fruit at two physiological stages of fruit development, were studied using a new staining technique for the detection of cellulase isoenzymes in polyacrylamide gels following electrophoretic separation. Four to seven isoenzymes were detected in the shoot‐peduncle (zone A) and peduncle‐fruit (zone C) abscission zones; at least two of them could be detected at excision time, and of these at least one could not be connected with abscission. In the young fruit, ethylene enhanced and 2,4‐D delayed both abscission and the formation of several isoenzymes. In the older fruit, ethylene enhanced and 2,4‐D delayed the formation of isoenzymes at a time where no abscission occurred any more in zone A. A slower but significant increase in most of the isoenzyme activity detected was also observed in abscission zone A of untreated older fruit explants after excision. These results fully agree with those reported earlier in relation to total cellulase and polygalacturonase activity (Greenberg et al., Physiol. Plant. 34: 1, 1975) tested at the same stages of fruit development. It is suggested, that the generality of the concept that a rise in hydrolytic enzymes in the abscission zone is necessarily followed by separation of the organ should be re‐evaluated.
Calcium Ions Protect Beet Root Cell Membranes against Thermally Induced Changes
Authors: TOPROVER YOCHEVED , GLINKA Z.
Published: April 2006

The initial heat induced increase in permeability of beet (Beta vulgaris L.) root cell membranes, as measured by betacyanin efflux, is reversible. The leakage of betacyanin stopped when tissue held for 90 min at 45°C was transferred to 27°C.

Stronger heat treatments, 10 min at 60°C or 150 min at 45°C, resulted in a continuous release of betacyanin indicating an irreversible change in membrane structure.

Calcium ions inhibited the heat induced betacyanin efflux only if this was due to a reversible increase in permeability.
Hormonal Control of Germination under Saline Conditions of Three Halophytic Taxa in the Genus Suaeda
Authors: BOUCAUD JEAN , UNGAR IRWIN A.
Published: April 2006

The interaction between hormones and salinity on seed germination of three halophytic taxa in the genus Suaeda: S. maritima (L.) Dum. var. flexilis Focke and var. macrocarpa Moq., and S. depressa (Pursh) Wats, was studied. Exogenous applications of kinetin and gibberellic acid (GA3) were applied in order to determine if either of these growth‐promoting hormones would promote germination in the two dormant taxa, Suaeda depressa and S. maritima var. flexilis and to see if osmotically induced dormancy by NaCl could be alleviated. Our results indicate that gibberellic acid is capable of breaking dormancy in these species with dormant seeds, but kinetin proved to be ineffective. A seed dormancy that was induced by osmotic stress could also be alleviated by treatments with gibberellic acid. Endogenous concentrations of both cytokinins and gibberellins were measured in seeds exposed to osmotic stress (0.85 M NaCl), and we found a reduction in cytokinin activity in these three taxa. Gibberellin‐like activity was reduced in S. depressa when seeds were soaked in 0.85 M NaCl.
Water Flow in Wheat Seedlings after Small Water Deficits
Authors: NORDIN ÅSA
Published: April 2006

Transpiration and water uptake were measured simultaneously using a micro‐wave hygrometer and a recording potometer. Wheat seedlings (Triticum aestivum L. cv. Weibulls Starke) were kept with the roots at +1°C in nutrient solution and with the shoots in air at 20°C for 24 h, a treatment which induced a decrease of about 2% in relative water content of the leaves. The induced deficit rapidly disappeared after returning to normal root temperatures (20°C).

The treatment produced after‐effects on steady rates of water absorption and transpiration in light, whereas the times taken for transient changes in transpiration brought about by changes in light conditions were not affected. The after‐effects were not completely eliminated 24 h after removal of stress. The magnitude of the after‐effects varied with the leaf water content, though some contribution of root cooling to the after‐effects cannot be excluded. The decreased water flow through the plant after removal of stress can be attributed mainly to increased stomatal resistance and not to effects on root conductivity. The increased stomatal resistance appears linked to increased membrane permeability rather than to a decrease in the active mechanism for ion uptake.
Modifications du rythme de fructification de Coprinus congregatus par le dépôt de carpophores mûrs exogènes à la surface des cultures
Authors: MANACHERE G.
Published: April 2006

Changes in Fruiting Rhythm of Coprinus congregatus by Addition of Exogenous Mature Sporophores on the Surface of Cultures.

Researches were performed over the regulating effect of mature sporophores on the fruiting rhythm of Coprinus congregatus Bull. ex Fr. Placing exogenous mature fruit‐bodies on the vegetative mycelium before the accomplishment of the first flush gives an abundant and perfectly synchronized fructification for this flush. But the fruiting rhythm is then disturbed: compared to control cultures, less sporophores are produced in the following flushes, and, in most cases, the cultures are finally characterized by fewer flushes than the controls. The nature of the substance(s) hypothetically produced by mature sporophores, which may regulate the production of other fruit‐bodies, and, correlatively, the fruiting rhythm, is as yet unknown.
Uptake and Transport of Calcium and Phosphorus in Lolium perenne in Response to N Supplied to Halves of a Divided Root System
Authors: BARTA A. L.
Published: April 2006

The uptake and transport of Ca2+ and HPO42− from roots of Lolium perenne L. was studied using variable N nutrition supplied to halves of a divided root system. Plants were grown for 4 weeks in solution containing 0.11 mM NO3−–N; then one‐half of the root system was supplied with either 4.0 mM NO3−–N or 0.28 mM NH4+–N while the other half of the root system remained in low‐N solution.

Uptake and transport of Ca2+ increased and uptake of HPO42− declined in root halves supplied with high NO3−–N for 16 h. After supply of high NO3−–N or NH4+–N to half the root system for 6 days, the roots supplied with high‐N exhibited significantly higher rates of uptake and percentage transport to shoots of both Ca2+ and HPO42−–. However, in neither the 16‐h nor 6‐day treatment did Ca2+ or HPO42− uptake of the root half supplied with low N differ significantly from the control (low N supplied to both halves of the root).

Significantly higher N concentrations were found in low‐N supplied roots (compared to the control) as a result of internal translocation of N from high‐N supplied roots to low‐N supplied roots. Although N concentration in the low‐N supplied roots increased, uptake rates of Ca2+ or HPO42− did not change implying that external N concentration may be the important factor which influences or governs N mediated uptake responses. This would further suggest that the site of uptake regulation for Ca2+ and HPO42− exists on the outer plasma membrane which is in direct contact with the external solution.

Transport of Ca2+ and HPO42− to the shoot was generally increased in low‐N root halves after 6 days of high‐N supply to the other half of the root. This implies that plant growth demand may be a major factor in regulating rates of Ca2+ and HPO42− transport from roots to the shoot. It also reinforces the hypothesis that uptake and transport of ions out of the root are separately controlled or regulated in the plant.
Effect of Prolonged Geo‐stimulation and Presence of 32P on the Elongation of Lateral Shoots of Decapitated Pea Seedlings
Authors: HUSAIN SYED MUSHTAQ
Published: April 2006

The effects of prolonged geo‐stimulation and presence of 32P on 3‐leaf decapitated pea (Pisum sativum L. cv. Alaska) seedlings were studied with regard to lateral bud elongation as well as accumulation and recovery of isotope.

Prolonged geo‐stimulation favoured the dominance of basally located, upwardly directed buds and suppressed the elongation of subapical bud — a gravimorphic response similar to the one shown by intact geo‐stimulated branches of woody plants. Basal bud 2 was an exception as it dominated both in the above‐ and below‐axis position.

Accumulation of 32P in buds was the result of their own growth, whereas in the other parts of the seedlings accumulation of isotope was not necessarily related to growth.

Geo‐stimulation affected 32P recovery in redistribution experiments, whereas it had no effect in distribution experiments. In the former, the decrease in the isotope level in the seedling suggests a loss of 32P.

Prolonged presence of 32P in the seedlings had a deleterious effect on bud elongation.
The Content of Elements of Mineral Nutrition in Leaf Parts of Different Colour in Plants of the variegata Type
Authors: SARIĆ M. R.
Published: April 2006

The contents of some elements in green and whitish yellow parts of the leaves of Hedera helix and Acer negundo were examined. The contents of N, P and K were considerably higher in whitish yellow parts of the leaves compared with the green ones, and contrary to Ca in both plant species. Mg behaved like N, P and K in Hedera but like Ca in Acer. The same results were obtained in the leaves which were completely green or whitish yellow. The metabolic activities in different parts of the leaves were evaluated on the basis of the content of the individual elements. Differently coloured parts of the leaves of variegata type show differences not only in morphology and structure but also in their metabolic activity.
Hydraulic Resistance of Rough Lemon Roots
Authors: RAMOS CARLOS , KAUFMANN MERRILL R.
Published: April 2006

A pressure chamber technique was used to estimate hydraulic root resistance in rough lemon (Citrus jambhiri Lush.) seedlings. The effect of previous water stress on hydraulic root resistance was evaluated. A factorial 3 × 3 design with four replications was established with potted rough lemon seedlings in a growth chamber. Three water‐stress treatments were applied by watering at intervals of 1, 2 and 3 days, and root resistance measurements were made after 6, 12 and 18 days of treatment. Plants that had experienced mild and severe water stress (irrigation interval of 2 and 3 days, respectively) had higher hydraulic root resistances after several drying cycles than those plants irrigated daily. Additional cycles had no significant effect. The increase in root resistance was not due to decreased root growth but apparently to changes in the permeability of the root cell membranes or to increased suberin deposition in the cell walls of the cortical cells. In a short‐term experiment (1 h), temperature strongly affected water flow through rough lemon roots in the range 5 to 35°C. Temperature influenced root membrane permeability, since reduced blow could not be explained by changes in water viscosity.
Activities of Enzymes Relating to Starch Synthesis and Endogenous Levels of Growth Regulators in Potato Stolon Tips During Tuberization
Authors: OBATA‐SASAMOTO HAMAKO , SUZUKI HIROSHI
Published: April 2006

Changes in contents of starch and protein, and activities of enzymes involved in starch synthesis were studied during tubcrization of stolon tips of Solanum tuberosum L. cv. Irish Cobbler. Starch content and activities of phosphorylase and granule‐bound starch synthctase based on fresh weight increased rapidly in the early phase (stage I, the stolon tips just before swelling; stage 2, the swelling tips; stage 3, young tubers of 0.2–0.5 cm diameter), and they all remained nearly unchanged in the later phase (stage 3 to stage 6, young tubers of 3.5 cm diameter). The content of soluble protein based on fresh weight remained unchanged. Activities of soluble starch snythetase and ADP‐glucose pyrophosphorylase were not detected at stage 1 and 2, but increased at later stages.

Endogenous levels of auxin, cytokinin and gibberellin were assayed for the materials at the corresponding developmental stages. Auxin content was high at stages 1 and 2, and lowered at later stages. Cytokinin content increased abruptly at stage 6. Gibberellin content was low at all stages.

The internal conditions for starch deposition and tuberization in potato were discussed in regard to regulation of enzyme activities by growth regulators.
Uptake of Nitrate by Mutants of Arabidopsis thaliana, Disturbed in Uptake or Reduction of Nitrate
Authors: DODDEMA HENK , TELKAMP G. P.
Published: April 2006

The uptake of nitrate by wildtype plants and chlorate‐resistant mutants of Arabidopsis thaliana (L.) Heynh. was studied by intermittent or continuous measurement of the nitrate concentration of the ambient solution. The uptake rate in the wildtype and the nitrate reductase‐less mutant B 25 showed a dual‐phase relation ship with concentration. Each phase showed Michaelis‐Menten kinetics although multiphasic patterns within each phase could not be excluded. A dual‐phase relationship was also found in the uptake mutant B I. Here, however, phase II did not follow Michaelis‐Menten kinetics and uptake rate of nitrate in the phase II concentration range was considerably lower in the B 1 mutant than in the wildtype. It is concluded that the mutation in B I has disturbed phase II of the nitrate uptake, without affecting phase I, which leads to the suggestion that uptake of nitrate in Arabidopsis is mediated by at least two independent uptake mechanisms.

The nitrate uptake rate showed an optimum at pH 8, and it was not stimulated by the presence of calcium. Ammonium had different effects on nitrate uptake: a direct effect, when it was present during the uptake of nitrate, resulting in a release of nitrate and a reduced rate of uptake, and an indirect inhibitory effect, possibly caused by assimilation products of ammonium, which is most pronounced after growth on ammonium as the sole nitrogen source or in long‐lasting uptake experiments in the presence of ammonium. Chlorate also showed a multiple effect, an inhibiting one which proved to be competitive and, at very low concentrations of chlorate, a stimulating one. Evidence was obtained that chlorate and nitrate arc taken up by the same carrier.
Isolation of Mesophyll Protoplasts of Nicotiana rustica and Their Regeneration into Plants Flowering in vitro
Authors: GILL RAVINDER , RASHID A. , MAHESHWARI S. C.
Published: April 2006

Protoplasts were isolated from leaves of in vitro grown plants of Nicotiana rustica L. by the one step enzymatic method. With 3% cetlulase in 0.5 M mannitol at 25°C and pH 4.6, within 10–12 h about half the total cells were transformed into protoplasts. The enzyme activity had two pH maxima, one at pH 3.5 and the other at pH 6.5, indicating the presence of isoenzymes. A time‐course study at different temperatures indicated that ai 30°C the protoplasts’ liberation was quicker but it resulted in their subsequent bursting. The protoplasts were cultured in liquid as well as on agar‐jelled medium of Ohyama and Nitsch (1972) supplemented with 2.4‐D and benzylaminopurine, each at I mg/1. and 14% sucrose. Regular divisions could be seen only on agar‐jelted medium. Colonies on transfer to Murashige and Skoog (1962) medium, containing IAA and kinetin, differentiated into plantlets. These plants, within 2 months, flowered in vitro and set seed of which about 20% germinated.
The Effect of Photosynthetic Enhancement on Photorespiration in Sinapis alba
Authors: NILSEN STEIN , HAUGSTAD MAY , HOLMEN AASE T.
Published: April 2006

In Sinapis alba, the Emerson enhancement effect, measured as CO2 uptake, was significantly lower in an O2‐free atmosphere than in normal air. Photorespiration, when measured as 14CO2 release after a period of 14C‐photosynthetic labeling in white or monochromatic light, was reduced during photosynthetic enhancement. The 14C‐glycolate pool and the 14C‐labeled amino acids associated with the glycolale pathway (glutamate, glycine and serine) decreased during photosynthetic enhancement when Pholosyslem I was ‘overexcited’. This demonstrates that photosynthesis and photorespiration are oxygen dependent and that photorespiration is wavelength dependent in Sinapis alba. The effect of oxygen on pholosynthetic enhancement and photorespiraion, as well as the effect of wavelength on these processes suggest that light is involved not only in the production of glycolate, but also in its further metabolism. It seems that Photosystem I is a key factor in the regulation of glycolate metabolism. Furthermore, the product from the consumption of glycolate in a reaction associated with Pholosystem 1 does not seem to be metabolized via the glycolate pathway.
Influence of Aryl Esters of Indole‐3‐acetic and Indole‐3‐butyric Acids on Adventitious Root Primordium Initiation and Development
Authors: HAISSIG BRUCE E.
Published: April 2006

Synthetic aryl esters of indole‐3‐acetic acid (IAA) and indole‐3‐butyric acid (IBA) greatly enhanced adventitious root primordium initiation in bean (Phaseolus vulgaris L. cv. Top Crop) and jack pine (Pinus banksiana Lamb.) cuttings, respectively. Bean cuttings produced 95 to 154% more macroscopically visible root primordia in 2 days when treated with phenyl indole‐3‐acetate (P‐IAA), in comparison with an equal concentration of IAA. Substantial but lesser increases occurred when treatment was done with 3‐hydroxyphenyl indole‐3‐acetate (3HP‐IAA). On a molar basis, either P‐IAA or 3HP‐IAA were 10 or more times as efficient as IAA in inducing adventitious root primordium initiation in bean cuttings. Methyl indole‐3‐acetate was no more effective than IAA in these tests.

Phenyl indole‐3‐butyrate (P‐IBA) consistently enhanced the number of rooted jack pine seedling cuttings by 11 to 12% in comparison with a 27% higher concentration of IBA.

The number of elongated roots (2 mm or more) after 5 days was 165 to 276% greater for P‐IAA than for IAA‐treated bean cuttings. Similar but lesser increases occurred as a result of 3HP‐IAA treatment. P‐IBA in comparison with IBA treatment did not influence either the number of roots or length of the longest root per rooted jack pine cutting.

Enzymes in bean and jack pine cuttings hydrolyzed the aryl esters. However, check experiments showed that initial integrity of the esters was required for enhanced activity in inducing root primordium initiation. Treatment of bean cuttings with hydrolysates of P‐IAA, or with IAA and phenol, alone or combined, did not influence root primordium initiation or development in a manner different from treatment with IAA alone.
Importance of Time Constants in an Open Flow System: Mathematical Correction of Fast Ethylene Kinetics in Physiological Studies
Authors: DE GREEF J. A. , VEROUSTRAETE F. , VAN WIEMEERSCH L. , FREDERICQ H.
Published: April 2006

A mathematical analysis for fast changes of ethylene concentration in an open flow system (non‐steady‐state conditions) is presented and experimentally tested. In this way it becomes possible to determine true values of ethylene production in the minute range following physiological and environmental changes which influence ethylene evolution. By this procedure ethylene kinetics can also be compared in absolute values independent of flow rate and plant chamber volume.
Time‐course of Nitrate Uptake and Nitrate Reductase Activity in Nitrogen‐depleted Dwarf Bean
Authors: BRETELER HANS , HÄNISCH TEN CATE CHARLOTTE H. , NISSEN PER
Published: April 2006

The rate of nitrate uptake by N‐depleted French dwarf bean (Phaseolus vulgaris L. cv. Witte Krombek) increased steadily during the first 6 h after addition of NO3 ‐After this initial phase the rale remained constant for many hours. Detached root systems showed the same time‐course of uptake as roots of intact plants.

In vivo nitrate reductase activity (NRA) was assayed with or without exogenous NO3‐ in the incubation medium and the result ing activities were denoted potential and actual level, respectively. In roots the difference between actual and potential NRA disappeared within 15 min after addition of nitrate, and NRA increased for about 15 h. Both potential and actual NRA were initially very low. In leaves, however, potential NRA was initially very high and was not affected by ambient nitrate (0.1–5 mol m‐3) for about 10 h. Actual and potential leaf NRA became equal after the same period of time. In the course of nitrate nutrition, the two nitrate reductase activities in leaves were differentially inhibited by cycloheximide (3.6 mmol m‐3) and tungstate (1 mol m‐3). We suggest that initial potential NRA reflects the activity of pre‐existing enzyme, whereas actual NRA depends on enzyme assembly during NO3‐ supply.

Apparent induction of nitrate uptake and most (85%) of the actual in vivo NRA occurred in the root system during the first 6 h of nitrate utilization by dwarf bean.
Temperature Sensitivity of Daily Respiratory Patterns Entrained through Phytochrome Action in Lemna paucicostata Strain 6746
Authors: HILLMAN WILLIAM S.
Published: April 2006

The respiration rate of heterotrophic Lemna paucicostata Hegelm. 6746 cultures at 26–27°C and given a brief pulse of red light, assumes patterns with properties dependent on the nitrogen source supplied. In a search for conditions specifically affecting features of those patterns expressing photperiodic timing, their amplitudes have been measured as relative peak height (RPH) — the increased height at the daily peak as a proportion of the average daily minimum — at both 21°C and 28°C. On nitrate, ammonium or aspartate medium, RPH is reduced roughly 70% at 21°C as compared to 28°C, but on nitrogen‐deficient medium the reduction is only 20–30%. Yet growth and the actual intensity of respiration are not differently temperature sensitive on NO3 and N‐deficient media. Nor does RPH itself correlate with growth rate.

Previous evidence indicates that patterns on NO3 and NH4 media reflect photoperiodic timing and that those on aspartale and N‐deficient media do not; hence the temperature sensitivity of RPH does not correlate with whether or not a pattern reflects photo‐periodic timing. However, different daily patterns arc elicited by pulses of red or far‐red on NO3. NH4 and aspartale media but not on the N‐deficient. Hence the temperature sensitivity of RPH does correlate with the degree to which the patterns distinguish between red and far‐red, which is to say between high anti low levels of Pfr‐phytochrome. This suggests that high temperature sensitivity in RPH reflects a reaction limited by N assimilation and saturating only at relatively high levels of Pfr.
Imaging by Delayed Light Emission (Phytoluminography) as a Method for Detecting Damage to the Photosynthetic System
Authors: BJÖRN L. O. , FORSBERG A. S.
Published: April 2006

An improved apparatus for obtaining luminescence (delayed light emission) images of plants is described. It consists of a phosphoroscope equipped with an imaging lens and an electronic image intensifier. It is also equipped with light‐sources for obtaining images with reflected light and fluorescence light.

It is shown that damage to the photosynthetic system caused by virus, insects, high or low temperature, ultraviolet radiation, or herbicide, and also chioroplast senescence as part of a normal developmental process, can be followed by this non‐destructive method. In many cases changes which are not visible in fluorescence images are clearly seen in luminescence images.
Epicuticular Wax and Cuticular Resistance in Rice
Authors: O'TOOLE J. C. , CRUZ R. T. , SEIBER J. N.
Published: April 2006

High leaf cuticular resistance has been reported as a component adaptation of plants to drought prone regions, Experiments were conducted to evaluate and characterize the role of epicuticular wax as a component of cuticular resistance to water vapor loss from rice (Oryza sativa L.) leaves. This information is necessary to determine the applicability of including higher cuticular resistance in an upland rice breeding program and to evaluate potential selection methods.

Diffusion porometry, electron microscopy, and gas liquid chromatography were employed. Measurement of cuticular resistance by leaf diffusive resistance porometry after stomatal closure by exposure of rice leaves to pure CO2 for 15 min was found sufficient to induce complete stomatal closure regardless of light level, and was superior to dark acclimation for this purpose.

Removal of epicuticular wax from rice leaves by chloroform dip significantly reduced the cuticular resistance. Stressed plants were observed to increase cuticular resistance, illustrating the responsive nature of this characteristic.

Gas liquid chromatography (GLC) of the chloroform leaf dip proved to be an expedient method of characterizing both quantitative and qualitative differences in the epicuticular wax of rice cullivars. The porometry and GLC techniques may be useful in selecting parents, spot checking in a pedigree program, or checking lines reaching the yield testing stage, but ate not well suited lor mass screening early generation progeny.

Significant differences were found in the two rice cultivurs, ‘63–83′, an upland adapted rice from West Africa, and “IR20′, bred and selected in submerged paddy culture in ihc Philippines, by tlie above methods of characterizing cuticular resistance and epicuticular wax. These results are of ecological significance to plant breeders.
Inhibitory Action of Blue and Far‐Red Light in the Flowering of Lemna paucicostata
Authors: OHTANI TAKESHI , ISHIGURI YOSHIO
Published: April 2006

In a new strain of short‐day duckweed (Lemna paucicostata T‐101), blue and far‐red light‐induced inhibition of flowering was investigated. Flowering of this strain failed to be induced under a short‐day photoperiod of blue and far‐red light, although it responded as a typical short‐day plant in red and white light. When the short‐day photoperiod of blue or far‐red light was terminated by a 15 min red light pulse, flowering recovered completely. This inducing effect of red light was reversed by subsequent exposure to far‐red light. Furthermore, it could be demonstrated that 30 min of blue light completely reversed the flowering inductive effect of 5 min red light and vice versa. Evidence is presented suggesting that the inhibitory action of blue and far red light may be due to the lowering of phytochrome Pfr levels below those required to start the dark reactions which lead to flowering. These results are discussed in relation to the time measurement system of photoperiodism.
The Different Components of the Movement and the Areas of Retention of Labelled Molecules after Application of [3H]‐ indolyl‐acetic acid to the Apical Bud of Vicia faba
Authors: BOURBOULOUX ANDREE , BONNEMAIN JEAN‐LOUIS
Published: April 2006

After application of [3H]‐auxin (0.8 nmol) to a young leaf of Vicia faba L. cv. Aguadulce. about 6% (1.1 × 10‐2 nmol) of applied IAA enters the stem during the first 6 h of transport. This corresponds to a [3H]‐auxin flux which is probably not very different from the endogenous flux. A wave of [3H]‐ auxin moves down to the roots mainly among preferential pathways situated in the vascular bundle. This movement is accompanied and followed by certain events: (I) In the upper part of the stem, some radioactive molecules leave the pathways of polar transport and enter the young leaves near the donor leaf. (2) In other parts of the stem, the auxin transport is highly polar. As the peak of the wave approaches and passes a node with an axillary bud. and for a few hours afterwards, there is no clearly detectable radioactivity in this bud, although the nodal tissues are very radioactive. (3) A retention of labelled molecules often occurs in the nodes. (4) Retention of label is regularly seen in the basal part of the first internode and in the hypocotyl, which together form that part of the axis where Ifle highly inhibited cotyledonary buds are found. This retention is still manifest a week after the downward transport of [3H]‐auxin. (5) After 48 h. a high proportion (about 45%) of the [3H]‐auxin exported by the donor leaf is found in the roots. (6) Subsequently, a part of the label returns to the upper parts of the plant, and especially to the leaves, where it normally appears to be immobilized. (7) As time goes on some labelled molecules, probably coming from different areas, enter the axillary buds.
14CO2 Fixation and Compartmentation of Carbon Metabolism in a Recombined Chloroplast‐ ‘Cytoplasm’ System
Authors: LARSSON CHRISTER
Published: April 2006

The Compartmentation of 14CO2 fixation and concomitant metabolism of l4C‐iabelled products in a recombined system, composed of isolated intact spinach (Spinacia oleracea) chloroplasls and a ‘cytoplasm’ fraction, has been studied. Addition of ‘cytoplasm’ to chloroplasts fixing 14CO2 increased the label in hexoae monophosphates outside the chloroplasts at the expense of excreted dihydroxyacetone phosphate. The label in ammo acids was increased both inside and outside the chloroplasts. The results support the view that chloroplasls are not able to make 2‐oxoacids for amino acid synthesis directly from fixed CO2, but have to co‐operate with the cytoplasm and other organelles. The results also show that recombined systems can be useful for studies on the compartmen tation of carbon metabolism in pholosynthesizing plant tissues.
Self inhibition of the Agaricus bisporus Spore by CO2 and/or γ‐Glulaminyl‐4‐hydroxybenzene and γ‐Gtutaminyl‐3,4‐benzoquinone: A Biochemical Analysis
Authors: RAST DORA , STÜYSSI HANS , ZOBRIST PETER
Published: April 2006

Chemical and enzymological analyses have been carried out to study the mode of action of CO2, in inhibiting germination in Agaricus bisporus and to test the suggestion (Vogel and Weaver, 1972. Exp. Cell Res. 75: 95, Vogel et at, 1974. Am. J. Pathol. 76: 165) that γ‐glutaminyl‐4‐hydroxybenzene (GHB) and/or γ‐glutaminyl‐3,4‐benzoquinone (GBQ) would inhibit the succinate dehydrogenase (SDH) in the mushroom spore and thus represent the causal agent(s) of its dormancy. Evidence is presented that the impairment of SDH is brought about by Ihe CO, fixation product oxaloacelate which is formed in the pyruvate carboxylase reaction, and a mechanism is proposed for the release of the SDH inhibition when activating the spores. These are almost devoid of GHB, whereas fruit bodies of all developmental stages contain considerable amounts of the phenol. GBQ is absent in the spore, and its occurrence in mushroom fruit body extracts appears to be an artifact of extraction. Apart from these analytical results, theoretical reasons are given that vouch against the involvement of the phenolics in the inhibition of SDH in vivo.
Effects of Brassin‐Complex on Auxin and Gibberellin Mediated Events in the Morphogenesis of the Etiolated Bean Hypocotyl
Authors: YOPP JOHN H. , COLCLASURE G. CRAIG , MANDAVA NAGABHUSHANAM
Published: April 2006

The excised, hooked bean hypocotyl was the system used to determine wheiher the ‘auxin‐ and gibberellin like’ effect of the lipoidal pollen extract, Brass in‐complex (Br), were mediated through, or independent of, auxin and gibberellin. The morphogenetic events of hook opening and hypocotyl elongation in this system are regulated by auxin and gibberellin, respectively.

Brassin complex, like IAA, elicited a book closure in (he dark and retarded its opening in red light. This effect was synergized by T1BA, IAA and the presence of the auxin‐producing organs, the epicotyl and cotyledons. Br‐elicited hook closure was inhibited by the antiauxin. PCIB.

Both GA3 and Br totally reversed the light inhibition of hypocotyl elongation. The GA3‐effect, but nol the Br elicited elongation, was overcome by Ancymidol. Hypocotyl elongation was partially inhibited by TIBA and PCIB. suggesting a possible auxin involvement also in this effect of Br.

Br may elicit its growth responses through an effect on endogenous auxin levels, In this way it is different from other lipoidat growth regulators, such as the oleanimins which require the presence of exogenous growth regulators for activity.
Genetic Analysis in Wood‐Decaying Fungi I. Genetic Variation and Evidence for Allopatric Speciation in Pleurotus ostreatus using Phenoloxidase Zymograms and Morphological Criteria
Authors: PRILLINGER HANSJÖRG , MOLITORIS H. PETER
Published: April 2006

Using electropherograms (zymograms) of the phenoloxidase laccase and characteristics of mycelial growth and fruit body production, a distinct morphological and biochemical differentiation of two geographically isolated (allopatric) populations of the wood‐rotting basidiomycete Pleurotus ostreatus became evident. No limitation in their outbreeding ability was observed, however. A specific secretory mechanism for an extracellular laccase, genetically different in the two geographical races, could be detected. An approximately 1: 1 segregation of this laccase band in the F1 generation indicates that specific secretion of this enzyme is controlled by one gene only, Different degrees of genetic variation as shown by differences in the respective laccase spectra were found in the two geographical races. Only one enzyme band out of nine multiple laccases was found to be specific for fruit bodies. The value of zymograms for chemotaxonomic purposes, for the understanding of microevolution and for determination of genetic variation in fungi is critically discussed.
Secondary dormancy (skotodormancy) in seeds of lettuce (Lactuca sativa cv. Grand Rapids) and its release by light, gibberellic acid and benzyladenine
Authors: BEWLEY J. DEREK
Published: April 2006

Lettuce seeds (Lactuca sativa L. cv. Grand Rapids) imbibed in darkness at supra‐optimal temperatures (23 ± 1°C) develop a secondary dormancy, termed skotodormancy. The seeds first lose their ability to be promoted to germinate by gibberellic acid, and then lose their ability to be promoted by red light. A combination of red light and gibberellic acid will break skotodormancy for longer than either alone, but red light and benzyladenine together are much more effective. Desiccation of skotodormant seeds does not diminish their dormancy. Embryos dissected from skotodormant seeds will germinate, and are as capable of radicle expansion in the osmoticum polyethylene glycol as are newly‐imbibed seeds. Hence skotodormancy is a whole seed dormancy and does not reside within the embryo as an inherent block to germination processes, but as an inability to respond to the stimulation of red light or to hormone.
Cadmium cytotoxicity and variation in nuclear content of DNA in Euglena gracilis
Authors: BONALY J. , BARIAUD A. , DURET S. , MESTRE J. C.
Published: April 2006

Cultures of Euglena gracilis (strain Z from French CNRS collection) can be made cadmium resistant if grown in a medium with 5x10‐4M cadmium chloride. This resistance is reflected by the appearance of a second exponential growth phase. The development of this resistance was studied at the cellular level by determining the relative content of DNA at different stages of the cell cycle in an asynchronously grown culture. The culture was followed until the second, cadmium resistant, growth phase had reached its stationary state.

During the first exponential growth phase, cells were mostly in the late period of DNA synthesis (stage S of the cell cycle), or in the gap preceding mitosis (stage G2 of the cell cycle). In addition, some cells contained high multiples of the normal amount of DNA. In the beginning of the second exponential growth phase, a few cells were again in G1 (the post mitotic stage of the cell cycle preceding DNA synthesis). These G1 cells were predominant at the end of the second growth period. During the second stationary phase the DNA content of the cadmium treated cells was similar to the stationary phase of the control culture. Cells had stopped growing in G1 with an unreplicated genome. The implications of these data are discussed.
Hormonal factors controlling the initiation and development of lateral roots
Authors: WIGHTMAN FRANK , SCHNEIDER ELNORA A. , THIMANN KENNETH V.
Published: April 2006

The decapitated primary root of 3‐day‐old Alaska pea seedlings has been used as a test system to determine the activities on lateral root formation of six auxins, six cytokinins and several other naturally‐occurring compounds. Their effects were assessed on (1) the initiation of lateral root primordia, (2) the emergence of visible lateral roots, and (3) the elongation of these laterals.

All the auxins, at the optimum concentration of 10‐4M, promoted the initiation of lateral root primordia, and all except 3‐indolylpropionic acid inhibited the elongation of the resulting lateral roots. Their effects on the emergence of laterals were small and varied. All the cytokinins, at 10‐6M and above, inhibited both the initiation and the emergence of lateral roots, zeatin being the most powerful inhibitor. The emergence process was about twice as sensitive as the initiation of primordia to the presence of cytokinins. The cytokinin ribosides were generally less active than the free bases. Abscisic acid and xanthoxin inhibited both emergence and elongation, the concentration for 50% decrease of emergence being about 10‐4M. Gibberellic acid had little clear effect on any of the three criteria. Nicotinic acid and thiamine at 10‐3M promoted both the initiation of primordia and their emergence: pyridoxal phosphate stimulated both emergence and elongation but did not influence the initiation of primordia. Adenine and guanine had little effect but decreased root elongation some 25%.

The strong inhibiting effect of the cytokinins may well be the basis for the marked inhibition exerted by the root‐tip on lateral root formation, while the promoting effects of auxins may explain the previously observed promotion of lateral root formation by the young shoot and cotyledons.
The effect of salinity on lipid composition and on activity of Ca2+‐ and Mg2+‐stimulated ATPases in salt‐sensitive and salt‐tolerant Plantago species
Authors: ERDEI LÁSZLÓ , STUIVER BEP (C.E.E.) , KUIPER PIETER J. C.
Published: April 2006

Lipid composition of the roots and the shoot of the salt‐sensitive Plantago media L., the salt‐tolerant P. maritima L. and the less salt‐tolerant P. coronopus L. was followed under saline conditions. In the roots of P. media the level of phospho‐, galacto‐ and sulpholipids decreased strongly with increased NaCl concentration, indicating decreased control of permeability of the root cell membranes. In the roots of the two salt‐tolerant species the level of most lipid classes was maintained or even raised up to 75 mM NaCl, and a decrease was noted only at higher NaCl concentrations. In P. maritima, a species from relatively nutrient‐rich habitats, decreased lipid levels in the roots and shoot were observed with increasing salinity in combination with a low nutrient availability. The Ca2+‐ and Mg2+‐stimulated ATPase activities of the microsomal fraction of the roots of P. maritima was decreased at a salinity level in excess of 150 mM, while in P. coronopus they were decreased at all NaCl levels tested. The obtained results are discussed as part of the adaptation of the species to salinity.
Some effects of humidity on the light reaction of photosynthesis in the lichens Cladonia impexa and Collema flaccidium
Authors: SIGFRIDSSON BJÖRN
Published: April 2006

Luminescence and fluorescence were measured at different relative humidities in the lichen Cladonia impexa Harm. Both parameters showed a constant value at relative humidities lower than 80%: thereafter they increased. Low relative humidity was found to decrease energy transfer from chlorophyll b to chlorophyll a. inhibit electron transport, lower electron holding capacity on the reduced side of photosystem two and impair far‐red‐induced afterglow, reflecting photophosphorylation. In Collema flaccidium Ach. Ach. energy transfer from the accessory pigments phycocyanin and phycoerythrin to chlorophyll a was only possible at high relative humidity. The results are interpreted as due to conformational changes caused by changed water content in the lichen.
Effect of benzyladenine on RNA and protein synthesis in intact bean leaves at various stages of ageing
Authors: Nailo Kunihiko , Nagumo Sigeru , Furuya Koichi , Suzuki Hiroshi
Published: April 2006

Primary leaves of intact bean plants (Phaseolus vulgaris L.) were treated with benzyladenine (BA) at different stages of ageing, BA promoted the synthesis of RNA, and soluble and insoluble proteins. The effects of BA stimulation differed depending on the age at which the leaf received the hormone treatment. In leaves attached to the plant, BA appeared to stimulate the rate of synthesis more than the rate of decomposition of RNA and protein, resulting in a net increase in RNA and protein. Both chloroplast and cytoplasmic ribosomes were still observed in intact yellowish green leaves. Polysomes in the cytoplasm increased remarkably when BA treatment was begun at late stages.
Gibberellin enhancement of the enzymic release of Pisum root cell protoplasts
Authors: Landgren Craig R.
Published: April 2006

Cultivar differences have been reported in the protoplast yields from Pisum sativum root cortical explants treated with preparations of commercial cellulase and pectinase. The presence of intracellular starch significantly influenced these protoplast yields. The application of gibberellin before or during the enzymic wall‐degradation increased the protoplast yields from two of the five cultivars tested. For tissues of‘Little Marvel’ pea roots, 10 mg 1−1 of gibberellin most effectively increased the release of protoplasts when the hormone preceded the enzyme incubation. One mg 1−1 of gibberellin was most effective at increasing the protoplast release when the tissues were treated with the hormone simultaneously with the wall‐degrading enzymes. Mitotic activity was significantly reduced in protoplasts derived from gibberellin‐treated tissues.
Soperoxide dismutase activity in ripening cucumber and pepper fruit
Authors: Rabinowitch Haim D. , Sklan David
Published: April 2006

Superoxide dismutase (SOD, EC 1.15.1.1) was identified from ripening cucumber (Cucumis sativus L.) and pepper(Capsicum annuum L.) fruits, Gel filtration revealed the presence of two major peaks of SOD with molecular masses of about 32 000 and 40 000. Peroxidase activity was observed mainly in material with a molecular mass above 70 000. SOD activity was inhibited by cyanide but not by chloroform‐ethanol, indicating a cupro‐zinc enzyme. SOD activity levels were high in immature‐green fruits of both species, declining in cucumbers to a minimum during the mature‐green stage and in peppers during the mature‐green and breaker stages. SOD levels increased again until peppers became orange and cucumbers turned yellow, and finally decreased with ripening. The possible connection between SOD activity and tolerance to sunscald is discussed.
High flexibility in growth and polyamine composition of the crucifer Pringlea antiscorbutica in relation to environmental conditions
Authors: Hennion Françoise , Frenot Yves , Martin‐Tanguy Josette
Published: April 2006

Although polyamine (PA) metabolism in plants responds to abiotic stresses, few studies have investigated this response in plants under natural conditions. Using high‐performance liquid chromatography, we studied the amine composition of the subantarctic crucifer Pringlea antiscorbutica R. Br. both in the field (Crozet and Kerguelen Islands) and under controlled temperatures in the laboratory. Plants collected from different sites showed a large variability of amine composition and contents. The aliphatic and acetylated amine composition of leaves allowed to statistically identify two groups. The first group, composed of Kerguelen coastal plants, was characterized by high levels of acetylspermidine and acetylspermine, showing the presence in P. antiscorbutica of this uncommon regulation pathway. PA acetylation may be induced in P. antiscorbutica under conditions of low water availability. The second group, composed of plants from Kerguelen altitude sites and plants from Crozet sites, showed high levels of free spermidine (Spd). In these plants, the ratio Spd/putrescine did not positively correlate with plant size as was found in developmental studies, suggesting that free Spd may be devoted to other aims, such as cold tolerance. Some differences between Crozet and Kerguelen plant responses suggested the possibility that different regulations of amine metabolism could take place in plants from these two islands. Agmatine accumulation pattern was diverse and suggested this amine to be sensitive to combinations of environmental factors. Studies on amine variation patterns in P. antiscorbutica provide insights into the roles of rarely reported amines, such as acetylated amines, in plant metabolic adaptation to abiotic stresses.
Measuring transpiration responses to summer precipitation in a Mediterranean climate: a simple screening tool for identifying plant water‐use strategies
Authors: Burgess Stephen Stewart Oakley
Published: April 2006

Rainfall utilization by vegetation is a complex function of the timing and magnitude of rain events, soil properties, evaporative demand and aboveground and belowground plant functioning. Understanding these interactions is highly relevant to a number of ecological problems, including salinization of cleared agricultural land in southern Australia. Ameliorative revegetation efforts require information on plant water‐use strategies; we used sap‐flow recordings to screen a range of species and identify four types of response to a large summer rainfall event: (1) no response, (2) delayed response, (3) small, rapid response and (4) large, rapid response. Proteaceous shrub species (e.g. Isopogon gardneri) rapidly increased transpiration up to five‐fold. Other shrubs such as Allocausarina campestris (Casuarinaceae) only increased transpiration two‐fold due to partial summer dormancy. Deep‐rooted Eucalyptus species (Myrtaceae, e.g. E. wandoo) were sufficiently reliant on antecedent soil water that they did not respond to summer precipitation. One hemi‐parasite species Nuytsia floribunda (Loranthaceae) required over 2 weeks to fully respond to rainfall, possibly due to water storage and changes to the hydraulic pathway. We discuss these results in terms of the ‘threshold‐delay’ model and the role of this screening method in assisting revegetation strategies.