bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of canavanine on IAA‐ and fusicoccin‐stimulated cell enlargement, proton extrusion and potassium uptake in maize coleoptiles
Authors: COCUCCI M. C. , ROSA S. DALLA
Published: April 2006

In maize coleoptiles (Zea mays F1 XL 640A, cv. Dekalb) canavanine and cycloheximide strongly and simultaneously inhibit cell elongation, H+ extrusion and K+ uptake, induced by IAA. They inhibit also, although to a much lesser degree, the same phenomena induced by fusicoccin. Cycloheximide severely depresses the incorporation of leucine into proteins, while canavanine leaves leucine incorporation almost unchanged. The data confirm that elongation, H+ extrusion and K+ uptake can be regarded as correlated processes; they also support the view that normal protein synthesis is essential for IAA‐induced growth, while this requirement is only partial in growth stimulated by fusicoccin.
Fractionation by centrifugation of leaf proteins from Brassica napus, Brassica oleracea, Helianthus annuus and Atriplex hortensis as a function of pH and temperature
Authors: LUNDBORG TOMAS
Published: April 2006

Chlorophyll‐free leaf protein concentrates for human consumption can be produced after separation of the chlorophyll‐associated protein from the rest of the leaf protein. This protein separation was studied in four plant species using heat fractiona‐tion. Press juice was prepared on a laboratory scale from field grown Atriplex hortensis, Brassica napus. Brassica oleracea and Helianthus annuus. Some further experiments were made with greenhouse grown plant material. After adjustment of pH to values between 4.0 and 8.0 the press juice was heated in water baths at 20, 35, 40, 45, 50, 55 and 60°C with or without 20 min holding time at appropriate temperature. Thereafter the juices were briefly centrifuged at 2500g. The protein content of the sediment was determined and the colour of the supernatant was observed.

The species showed different protein sedimentation patterns, especially at neutral and weakly alkaline pH. Brassica napus had rapidly sedimenting proteins, low temperature was sufficient for complete sedimentation of chlorophyll‐associated proteins and gave a high percentage of the total press juice protein as chlorophyll‐free protein. Atriplex hortensis had slowly sedimenting proteins irrespective of temperature, required high temperature for complete sedimentation of chlorophyll‐associated proteins and gave a low percentage chlorophyll‐free proteins. Brassica oleracea and Helianthus annuus showed intermediated properties. Reasons for these differences among the species are discussed.
Light effects on root formation in aspen and willow cuttings
Authors: ELIASSON LENNART , BRUNES LAILA
Published: April 2006

The effect of light on rooting of leafy cuttings of aspen (Populus tremula × tremuloides) and a willow hybrid (Salix caprea × viminalis) was investigated under controlled conditions in water culture. Two levels of irradiance were used, 40 and 8 W m−2. The lower level gave the best rooting of aspen cuttings, both when applied to the stock plants before the cuttings were taken and when given to the cuttings during the rooting period. Irradiation of the cutting base during the rooting period inhibited rooting almost completely in aspen and decreased the number of roots formed in the Salix hybrid.

Net photosynthesis in the cuttings of Salix decreased considerably after excision and increased again after formation of roots. Indirect evidence indicated that photosynthesis was even more affected in aspen cuttings. The possible roles of carbohydrates and inhibitors in the light effects are discussed.
Galactose, aspartate crossway and rhythm inhibition in Aspergillus niger
Authors: JEREBZOFF STEPHAN , JEREBZOFF‐QUINTIN SIMONE
Published: April 2006

When the glucose/K+ balance in the medium is favourable to rhythm expression in Aspergillus niger Van Tieghem, galactose has an inhibitory effect on amplitude but not on period length of the rhythm. Galactose is active when its level reaches 1/10 of that of glucose.

On liquid media a small quantity of glucose is necessary to start growth on galactose. Under these conditions U14C‐galactose is rather slowly metabolized. After 6 h of feeding on the labelled galactose medium, this sugar is converted into glucose, which is used both for the synthesis of compounds derived from C3 and C4 units and for synthesis of polysaccharides and perhaps small peptides. The labelling of the macromolecules always remains low. The insoluble carbohydrates of the mycelium are little affected by the type of sugar supplied to the fungus.

The metabolism on galactose differs from the metabolism on glucose mainly in a decrease of the free asparagine pool and a simultaneous equivalent increase of the free aspartate pool; such an effect could not be correlated with an increase of the aspartate aminotransferase activity. Supply of aspartate but not of gluta‐mate into the agar medium inhibits the rhythm amplitude. So, the damping effect of galactose on the rhythm might be at least partly due to its effect on the regulation of the aspartate cross‐way.
Spectral properties of a long‐wavelength absorbing form of protochlorophyll in seeds of Cyclanthera explodens
Authors: SUNDQVIST CHRISTER , RYBERG HANS , BÖDDI BÉLA , LÁNG FERENC
Published: April 2006

The in vivo absorbance spectrum of the inner seed coat of Cyclanthera explodens Naud. showed a main peak in the red region at 671 nm and a weak shoulder at about 640 nm. The pigments were extracted with acetone. separated by paper chromatography and analysed spectrophotometrically. The only detectable pigment was protochlorophyll. The in vivo fluorsecence emission spectra had two main peaks, one at 632 and one at 691 nm. The relation between the two peaks was changed when the exvcitation wavelength was altered from 440 to 460 nm. Excitation at 420 nm gave an additional fluorescence emission peak at 595 nm. These data indicate the presence of at least three forms of protochlorophyll in the Cyclantera seed coat. The spectrum of circular dichroism had a very intence and characteristic signal in the red region with a negative asymmetrical Cotton effect (664 (+), 669 (0) and 687 (−) nm). This indicates that at least one of the protochlorophyll forms is present in a more or less crystalline form.
Effects of cordycepin on IAA‐ and fusicoccin‐stimulated cell enlargement, proton extrusion and potassium uptake in maize coleoptiles
Authors: COCUCCI M.C. , ROSA S. DALLA
Published: April 2006

In maize (Zea mays F, XL 640 A, DEKALB) coleoptiles, cordycepin (3′‐deoxyadenosine) is very active in preventing the cell elongation. H+ extrusion and K+ uptake induced by IAA and, to a much lesser degree, the same phenomena induced by fusicoccin (FC). Cordycepin, while depressing uridine incorporation into RNA, does not decrease the ATP level or significantly influence the pyruvate level and leucine incorporation into proteins in this material. These results support the hypothesis that one or more proteins. whose synthesis is dependent upon short half‐life mRNAs, are essential for a full response to IAA. while this requirement is only partial in FC‐stimulation of growth. They also confirm the view that auxin‐ or FC‐induced activation of H+/K+ exchange plays an important role in mediating the effects of these compounds on cell enlargement.
Fractionation by centrifugation of leaf proteins from varieties and cultivars of Helianthus annuus and Helianthus debilis as a function of pH and temperature
Authors: LUNDBORG TOMAS
Published: April 2006

In order to select plant material for obtaining a high proportion of chlorophyll‐free protein from Helianthus species by heat fractionation, leaf extracts from 11 field grown cultivars of H. annuus and H. debilis were investigated. In addition, press juices from H. annuus cv. Kinesisk were supplied with salts or urea before heat treatment in order to increase the proportion of chlorophyll‐free protein during heat fractionation.

The extracts were adjusted to pH 5.0, 6.0 and 8.0; then left for 20 min at 20°C, 50°C or 60°C and centrifuged at 2,500 g. The highest percentage chlorophyll‐free protein of the total protein in the extract, more than 10%, was obtained for H. debilis cv. fl.pl. Sun Gold, H. annuus cv. Giganta, H. annuus cv. uniflorus and H. debilis cv. Stella, at pH 6.0 and 50°C.

The low percentage chlorophyll‐free protein obtained could be explained by the fact that a considerable part of the chlorophyll‐free protein sedimented at original pH, low temperature and low centrifugation speed. This sedimentation at low temperature was probably due to interactions of phenolics. Besides, if the chlorophyll‐associated membranes were highly fragmented during the disintegration of the plant material, the high temperature required to precipitate them completely led to further aggregation and thus to loss of chlorophyll‐free proteins.

Salts or urea present during heat treatment (pH 6.0/55°C for 20 min) did not considerably increase the proportion of chlorophyll‐free proteins obtained.
Effects of ultraviolet–B irradiances on soybean
Authors: TERAMURA ALAN H.
Published: April 2006

Soybean [Glycine max (L.) Merr. cv. Hardee] and wheat (Triticum aestivum L. cv. Jori) were grown from seed under four ultraviolet‐B irradiances and four levels of photosynthetically active radiation in a factorial design. The effects of ultraviolet‐B radiation on leaf number and area, total dry matter production, dry weight of component organs, and plant height were compared between soybean and wheat. Ultraviolet‐B radiation effects were dependent upon the level of photosynthetically active radiation incident during growth. Wheat and soybeans were both affected by low ultraviolet‐B radiation flux densities; however, they differed markedly in their growth responses and biomass allocation patterns. Substantial interactions between ultraviolet‐B and photosynthetically active radiation indicate a need for the measurement of longer wavelength radiation when evaluating the effects of ultraviolet‐B radiation on plant growth in natural conditions.
Effect of photoperiod and temperature on apical growth cessation in two ecotypes of Salix and Betula
Authors: JUNTTILA OLAVI
Published: April 2006

Apical growth cessation as affected by photoperiod and temperature has been studied in seedlings of two latitudinal ecotypes of Salix and Betula. The critical photoperiod for apical growth cessation at constant temperatures of 15 and 21°C was about 22 h for a northern (69°C39′N) and about 15–16 h for a southern (59°C40′N) ecotype of Salix pentandra. Fluctuating day/night temperatures (21°C/9°C, 15°C/6°C) induced apical growth cessation in northern ecotypes even at 24–h photoperiod. Disagreements in critical photoperiods found in various studies are discussed.
The effect of detergent treatment on methylene blue sensitized cytochrome b photoreduction in fractions from corn coleoptiles
Authors: WIDELL SUSANNE
Published: April 2006

It was previously demonstrated that photoexcited methylene blue can act as electron donor in red light induced reduction of a particulate b‐type cytochrome in fraction from etiolated corn coleoptiles (Zea mays L. WF 9 × Bear 38). It was postulated that the same cytochrome as the one active in blue light photoprocesses was involved. This study describes the effect of detergents upon such red light induced reductions in corn coleoptile preparations fractionated after differential centrifugation into 9 KP, 21 KP and 50 KP (500–9000 g pellet, 9000–21,000 g pellet and 21,000–50,000 g pellet, spun for 20, 20, and 45 min, respectively). Both Triton X‐100 (more effective) and deoxycholate (less effective and somewhat destructive) could be used as solubilizers if concentrations above the critical micellar concentration were chosen. Tween 40 was ineffective and dodecyl sulphate affected the cytochrome so that it lost its accessibility to electrons from photoexcited methylene blue. The recovery, measured as the ratio between light induced absorbance change (LIAC) in the Soret region after and before solubilization, was highest in 9 KP (70%) and lower in 21 and 50 KP fractions (50% and 43% respectively). The band in the Soret region in light minus dark spectra had its peak at longer wavelengths compared to the dithionite reduced minus no addition absorption difference band, whether the sample was solubilized or not. Similar results were obtained when the material was separated on a discontinuous sucrose gradient (15/28/33/45% w/w sucrose). In such a separation, the distribution of LIAC between fractions (collected at the interfaces) was about the same after solubilization as before (solubilization brought about a slight shift towards heavier fractions). The ratios of LIAC to the dithionite reduced minus no addition absorbance difference decreased upon detergent treatment. The LIAC still had its peak at longer wavelengths compared to the peak obtained upon dithionite reduction.

The usefulness of detergents in the purification of the particulate b‐type cytochrome is discussed.
Enzymatic, isoelectric, and molecular‐weight characterization of water‐soluble maize‐pollen proteins
Authors: ORTEGA E. I. , BATES L. S.
Published: April 2006

Maize (Zea mays L. cv. Kansas Drought Synthetic) pollen proteins were fractionated via a continuous tandem cascade ultrafiltration system into three molecular‐weight classes. Proteins from the whole extract and each fraction were further separated by polyacrylamide gel electrofocusing in the pH 5 to 9 range and characterized by their enzymatic activity and isoelectric point.

Twenty‐one protein bands were detected with Fast Green FCF staining. Esterase, peroxidase, leucine aminopeptidase, catalase, and amylase activities were located in 16 bands. Five bands remained unclassified. All the enzymes assayed, except amylase, were polymorphic. The extractions, fractionations and zymograms were reproducible and indicated that several protein bands contained at least two different enzymes with very similar molecular weight class and isoelectric point for each enzyme and protein band
Dichlorophenyl dimethylurea (DCMU) induced increase in chlorophyll a fluorescence intensity – An index of photosynthetic oxygen evolution in leaves, chloroplasts and algae
Authors: KULANDAIVELU G. , DANIELL H.
Published: April 2006

Dichlorophenyl dimethylurea (DCMU) treatment in photosynthetic samples resulted in an increase in the level of steady state chlorophyll a fluorescence at room temperature which was directly proportional to the photosynthetic efficiency. The applicability of this method for the rapid determination of the efficiency of oxygen evolution in leaves, algae, mesophyll cells and chloroplasts has been investigated. Especially reliable values with less than 5% error were obtained if the fluorescence measurements were made under low excitation intensities with a sample chlorophyll concentration below 1.0 μg/ml.
Varietal variation in uptake and utilization of potassium (rubidium) in high‐salt seedlings of barley
Authors: JENSÉN PAUL , PETTERSSON SUNE
Published: April 2006

Seedlings of eleven varieties of barley (Hordeum vulgare L.) showed differences in utilization of K+ from a full nutrient solution containing 3.0 mM K+. The K+ content of both roots and shoots was proportional to the fresh weights and dry weights after a week in the nutrient solution. The K+ use‐efficiency ratio, which indicates the efficiency of nutrient utilization (mg dry weight produced per mg K+ absorbed), differed significantly among the varieties. There was no correlation between influx of Rb+ and the content of K+. It is suggested that there are wide varietal differences in such genetically‐determined properties as ion influx and efflux and net ion transport to the shoot. Further‐more, the influx of Rb+ was closely linked to transpiration, probably due to a variety‐specific non‐metabolic part of Rb+ influx. Varietal differences in influx of Rb+ were more pronounced in high‐K+ roots than in low‐K+ roots with maximum rate of Rb+ uptake, but the rank of varieties was the same in each case. – Criteria for the selection of K+ use‐efficient varieties of barley are discussed.
Diurnal variation of root respiration rates and nitrate uptake as influenced by nitrogen supply
Authors: HANSEN G. K.
Published: April 2006

Root respiration rates of Lolium multiflorum supplied with nitrate or ammonium were measured continuously during several days (Exp. A). Net uptake rate of nitrate was similarly measured by an ion selective nitrate electrode in a system of flowing nutrient solution (Exp. B). Diurnal variation of in vitro nitrate reductase activity and nitrate content of tops and roots were determined (Exp. C). Two levels of irradiance were applied throughout, with day:night of 16:8 h.

Root respiration rates showed diurnal patterns, most pronounced in the nitrate treatment, with two peaks appearing about 6 and 16 h after commencement of the photoperiod. Respiration rates were highest in the nitrate treatment and at high irradiance. Respiration rates fell after removal of nitrogen, particularly in the nitrate supplied plant and at high irradiance. Net uptake rate of nitrate exhibited diurnal patterns, often with two peaks occurring at the same times as those of respiration rates. In vitro nitrate reductase activity of tops increased steeply 16 h after commencement of the photoperiod and remained at the high level during the following 8 h of darkness. Nitrate content of tops was highest during the 8 h dark period and fell at the start of the photoperiod. Possible controlling systems of the apparent coincidences of diurnal variation rates, net nitrate uptake and nitrate reduction are discussed.
Ammonium influence on nitrogen assimilating enzymes and protein accumulation in suspension cultures of Paul's Scarlet rose
Authors: MOHANTY BIBEKANANDA , FLETCHER JOHN S.
Published: April 2006

The influence of NH4+ on protein accumulation was examined by growing suspension cultures of Rosa cv. Paul's Scarlet on two defined media. Both contained 1920 μmol of NO3− but only one contained 72.8 μmol of NH4+. At the conclusion of a 14‐day growth period, cultures grown with NH4+ possessed twice as much protein as cultures grown without NH4+. The influence of NH4+ did not appear to be a substrate effect, since the amount of NH4+ provided accounted for only 10% of the nitrogen recovered in protein.

The provision of NH4+ in the starting medium increased the activity (μmol substrate. h−1· g−1 fr wt) of glutamate dehydrogenase and glutamate synthase, and reduced the activity of glutamine synthetase. A comparison of the total activity per culture for each of these enzymes with the rate of nitrogen incorporation into protein showed that the enzymatic potential of glutamine synthetase and glutamate dehydrogenase greatly exceeded the actual in vivo rate of nitrogen assimilation through the respective pathways. Thus it was concluded that the availability of either of these enzymes does not limit nitrogen assimilation in rose cells and the fluctuations in their level brought about by NH4+ was of no physiological importance.

The activity of glutamate synthase per culture approximated the rate of nitrogen incorporation into protein during early stages of growth, and for that reason may have limited nitrogen assimilation or caused a diversion of nitrogen through the alternative pathway to glutamate catalyzed by glutamate dehydrogenase.
Enzymatic activities of starch synthesis in potato tubers of different sizes
Authors: TSAY J. S. , KUO C. G.
Published: April 2006

The objective of this study was to determine the relationship between tuber weight and enzymatic activities involved in tuber starch synthesis. As tuber weight increased, the activities of sucrose synthetase, UDPG pyrophosphorylase, and granular starch synthetase escalated, whereas the activities of soluble starch synthetase and ADPG pyrophosphorylase stayed constant and that of phosphorylase declined. This suggests that when samples are taken to determine specific enzymatic activities, the sampling procedure should ensure that results do not vary because of differences in the tuber weight or size distribution.
Sucrose metabolism in Sorghum vulgare at ripening
Authors: SHARMA K. P. , BHATIA I. S.
Published: April 2006

Enzymes associated with sucrose metabolism in root, stem, leaf and grain of Sorghum vulgare Pers. (cv. JS 263) were studied at the ripening stage. Sucrose phosphate synthetase was dominating in the leaf and sucrose synthetase in the grain. Invertases were more active in leaf, root and stem tissues than in grains. The maximum activities of ADPG pyrophosphorylase and UDPG pyrophosphorylase were found in grains and leaves, respectively. Sucrose synthetase from grains catalyses both synthesis and cleavage of sucrose but the two activities differed in their responses to the effect of temperature, pH and type of buffer. The Km values of the enzyme for UDPG, ADPG, GDPG, TDPG and CDPG were 8.5, 5.3, 16.8 2.2 and 10.7 mM, and for UDP and ADP they were 17.2 and 55.0 mM respectively.
Nitrate assimilation in leaf blades of wheat of different age
Authors: POKHRIYAL T. C. , SACHDEV M. S. , GROVER H. L. , ARORA R. P. , ABROL Y. P.
Published: April 2006

A field experiment on wheat (Triticum aestivum L.) ev. Shera grown at 120 kg N ha−1 was conducted. Half of the dose of fertilizer N was applied at the pre‐sowing stage and the other half when the seedlings were one month old. The leaf blades were examined for their NO3− content and NO3− assimilatory activity at various stages of growth and development. Soil nitrate level at 50 cm depth was determined throughout the wheat growing season in terms of cencentration (μg/ml) and total amount (kg ha−1). The upper leaf blades were examined for their capacity to assimilate NO3−. Highly significant correlation between NR (nitrate reductase) activity and NO3− content in the leaf blades. NR activity and soil NO3−, and between soil NO3− and leaf blade NO3− was observed. Findings on low soil NO3− status during the reproductive phase and the capacity of the upper leaf blades to assimilate additional amounts of NO3−, point to the need for developing a programme of soil fertilizer application whereby all the leaf blades can utilize the NO3− optimally and thus result in greater N harvest.
Determination of 4‐chloroindole‐3‐acetic acid methyl ester in Lathyrus, Vicia and Pisum by gas chromatography – mass spectrometry
Authors: ENGVILD KJELD C. , EGSGAARD HELGE , LARSEN ELFINN
Published: April 2006

4‐Chloroindole‐3‐acetic acid methyl ester was identified unequivocally in Lathyrus latifolius L., Vicia faba L. and Pisum sativum L. by thin layer chromatography, gas chromatography and mass spectrometry. The gas chromatographic system was able to separate underivatized chloroindole‐3‐acetic acid methyl ester isomers.

The quantitative determination of 4‐chloroindole‐3‐acetic acid methyl ester in immature seeds of these three species was performed by gas chromatography – mass spectrometry using deuterium labelled 4‐chloro‐indole‐3‐acetic acid methyl ester as an internal standard. P. sativum contained approximately 25 mg kg‐1, V. faba 1–2 mg kg‐1 and L. latifolius 2 mg kg‐1 dry weight.
Ethylene as an endogenous inhibitor of root regeneration in tomato leaf discs cultured in vitro
Authors: COLEMAN WARREN K. , HUXTER TERRY J. , REID DAVID M. , THORPE TREVOR A.
Published: April 2006

We examined ethylene effects on root regeneration in tomato leaf discs cultured in vitro. Applied ethylene or Ethephon did not stimulate rooting in the leaf discs. In the presence of indoleacetic acid. 5 × 10‐6M, these substances significantly inhibited root formation. Ethylene production (nl C2H4· (24 h)‐1. flask‐1) was positively correlated with increased IAA concentrations at various times during the culture period and, as a consequence, with the rooting response after 168 h. However, separate testing of equimolar concentrations of seven different auxins and auxin‐like compounds showed no positive correlation between the rate of ethylene production and subsequent rooting response. Aeration of gas‐tight flasks containing leaf discs and absorption of ethylene evolved from the discs by mercuric perchlorate in gas‐tight flasks or pre‐treatment of leaf discs with AgNO3 significantly enhanced IAA induced root regeneration. Thus, these studies indicate that ethylene is not a rooting hormone per se. Furthermore, ethylene (whether applied externally or synthesized by the tissue) does not appear to account for the ability of auxin to stimulate rooting.
The utilization of organic nitrogen for growth of algae: physiological aspects
Authors: NEILSON ALASDAIR H. , LARSSON TOMMY
Published: April 2006

The ability of 27 algae belonging to 11 taxonomic divisions to grow at the expense of organic nitrogen was tested in axenic culture. Experiments were carried out in buffered media: morpholine propanesulphonic acid (MOPS) was used successfully for all fresh water strains except diatoms. It was not used as a nitrogen source by any strain examined but served as a good source of sulphur for four strains. The range of substrates used was extensive and included amino acids, urea, acetamide, urate and some nucleosides. Growth rates varied widely but growth yields were generally comparable to those attained with nitrate or ammonia except for substrates containing more than one utilizable nitrogen atom. Limited experiments were carried out in the dark, and it was found that a given substrate was equally suitable for both dark heterotrophic and photolithotrophic growth. Levels of chlorophyll a were measured during growth of two algae with nitrate, glycine and urate. With nitrate, levels of specific chlorophyll a declined some ten‐fold during growth: with poor substrates supporting only slow growth, levels were more uniform but were only 10–15% of those attained during growth with good substrates. One strain grown with MOPS as sole source of sulphur produced cultures with levels of chlorophyll a about half those found in sulphate‐grown cultures. Tolerance of sodium chloride was examined in a few strains and even putatively fresh water strains were found to be appreciably tolerant.
Modification of stress tolerance by dehydration pretreatment in winter rape hypocotyls
Authors: SHCHERBAKOVA ANNA , KACPERSKA‐PALACZ ALINA
Published: April 2006

Dehydration of isolated rape hypocotyls (Brassica napus L. var. oleifera L. cv. Górczański) to a water saturation deficít of about 60% resulted in increased tolerance to subsequent desiccation and to prolonged immersion in water. Dehydration pretreatment followed by restoration of tissue turgidity, caused a decrease in leakage of electrolytes, ultraviolet‐absorbing materials and ninhydrin‐reactive substances from the desiccated or water immersed hypocotyl tissue. A hardening effect of tissue dehydration is supposed to be related to an improved stability of cell membranes.
Gibberellin‐like substances and indole type auxins in developing grains of normal‐ and high‐lysine genotypes of barley
Authors: MOUNLA M. A. KH. , BANGERTH F. , STORY V.
Published: April 2006

Changes in gibberellin‐like activity and content of indole type auxins were investigated during grain development of the two high‐lysine barley (Hordeum vulgare L.) genotypes Sv 73608 and Risø 1508, and their corresponding normal cultivars Mona and Bomi.

A peak in gibberellin‐like activity was found in developing grains of the normal cultivars about 18 days after anthesis, whereas the grains of the high‐lysine genotypes showed a two to five times higher maximum about 3–4 days later.

The auxin content of the cultivar Bomi showed a maximum between the 22nd and the 29th day after anthesis, whereas, throughout their development the grains of the mutant Risø 1508 exhibited only about 1/10 of the maximum level of auxin found in the grains of Bomi. The normal cultivar Mona also displayed higher contents of auxin than the high‐lysine genotypes Sv 73608, particularly at the later stages of grain growth, but the differences in concentration were considerable smaller than for the pair ‘Bomi’—‘Risø 1508’.

It is suggested that auxins play an important role in the development of barley grains.
Changes in diffusion resistance of apple leaves undergoing rapid fluctuations in leaf temperature
Authors: WEST D. W. , GAFF D. F.
Published: April 2006

Transpiration was measured in apple leaves (Malus sylvestris Mill.) which were enclosed in a leaf chamber and subjected to rapid changes in leaf temperature. Fluctuations in leaf temperature produced parallel fluctuations in transpiration. The change in transpiration rate with change in temperature was found to be less than the theoretical value calculated from the change in water vapour density gradient from leaf to air. The results suggest the presence of a small and rapidly varying resistance to water vapour loss from the leaf. The magnitude of this additional resistance increased to a maximum value of approximately 1.5 s cm‐1 as the magnitude of the temperature change increased to a maximum of approximately 12°C.
Time course of uptake of 14C‐abscisic acid by Lemna gibba in relation to growth
Authors: TILLBERG ELISABETH , ELIASSON LENNART , ERICSSON TOM
Published: April 2006

The time course of growth of Lemna gibba L. in low concentrations of abscisic acid (ABA) and of uptake of 14C‐labelled ABA into the plants was followed for up to 15 days. Fresh weight increase was arrested when the plants were transferred to ABA solutions. This inhibition was greatest during the first days after which a marked recovery took place. Dry matter production was only slightly affected by ABA.

On a culture basis, the uptake of ABA was almost linear with time during the experimental period. The rate of uptake on a fresh weight basis was highest during the first two days but decreased rapidly from the third day. Most of the applied 14C remained in the culture solution throughout the experiments. Plants transferred to a solution without ABA retained most of their accumulated 14C. Possible explanations for the decrease in rate of ABA uptake and restoration of growth are discussed.
Biochemical changes in the developing seeds of Cuscuta campestris
Authors: CHARLES DENYS J. , SINGH MADHAV , SANWAL G. G.
Published: April 2006

Abstract Metabolic changes in developing Cuscuta campestris Yunck seeds were studied with respect to TCA‐soluble phosphate fractions, nucleic acids and the enzymes, viz, acid and alkaline phosphatase, neutral and alkaline FDPase, starch phosphorylase, α‐amylase ribonuclease, deoxyribonuclease and phytase. RNA and DNA contents increased steadily, and then remained stationary during the last two stages. The activities of all the enzymes studied increased with development with a sharp fall in the final stage. Interestingly, α‐amylase was present throughout the seed development. Phytic acid (16% of the total P) does not seem to function as phosphate reservoir, instead orthophosphate (13% of the total P) and nucleic acids (30% of the total P) may serve this function.
Effects of auxin and irradiance on the rooting of cuttings of Pinus sylvestris
Authors: STRÖMQUIST LARS‐HELGE , HANSEN JÜRGEN
Published: April 2006

Abstract Seedlings of Pinus sylvestris L. were grown under controlled conditions (temperature 20°C, photoperiod 17 h) at two irradiances, 8 or 40 W m‐2. Hypocotyl cuttings were excised and rooted at different irradiances in tap water solutions of indolebutyric acid (IBA). The fastest rooting and highest rooting percentage were obtained with cuttings from stock plants grown at 8 W m‐2 and treated with 10‐5M IBA for 21 days. The concentration of 10‐4M IBA inhibited root formation. In comparable treatments rooting was always better in cuttings from stock plants grown at 8 W m‐2 than in cuttings from stock plants grown at 40 W m‐2. The irradiance during the rooting period had only a minor influence on rooting. When cuttings from plants irradiated with 40 W m‐2 were treated with 10‐5M IBA for 21 days the rooting percentage almost reached the same level as in untreated cuttings from stock plants given 8 W m‐2. In cuttings treated with IBA during the whole rooting period, rooting was depressed in comparison to untreated cuttings. Aeration of the 10‐4M IBA solution increased the rooting percentage, but aeration had no effect on untreated cuttings and on cuttings treated with lower IBA concentrations.
Separation and analysis of steryl and wax esters from Dicranum elongatum
Authors: KARUNEN PIRJO , MIKOLA HEIKKI , EKMAN RAINER
Published: April 2006

Abstract Complete separation of the steryl and wax esters in the subarctic moss Dicranum elongatum was achieved on MgO thin‐layer plates without any notable alteration of the acyl and alkyl moieties of the esters. Gas chromatography‐mass spectrometry of the hydrolyzed fraction showed that the sterols (campesterol, stigmasterol, sitosterol, cycloartenol, 24‐methylene cycloartanol and an unidentified sterol) were primarily esterified with unsaturated fatty acids 18:2 ω 6, 18:3 ω 3 and 20:4 ω 6. In contrast, the wax alcohols (l‐octadecanol, phytol and geranylgeraniol) were mainly esterified with saturated fatty acids with 16:0, 18:0 and 20:0 as major components. No great differences were found in the fatty acid pattern of the steryl esters between different portions of the shoot. Slight differences, however, were found in the proportions of ω 3 and ω 6 fatty acids. In the wax esters a clear decrease was found in the proportions of 18:0 and 20:0 acids with increased shoot age accompanied by a slight increase in the proportions of 14:0, 20:4 ω 6 and phytenic acid.
Propagation of Hedera helix: Influence of irradiance to stock plants, length of internode and topophysis of cutting
Authors: POULSEN ALICE , ANDERSEN A. SKYTT
Published: April 2006

Abstract Stock plants of Hedera helix cv. Pittsburgh were grown in controlled environment rooms at four different irradiances (light intensities) 10, 22, 37 or 46 W m‐2 PAR (photosynthetically active radiation). The root formation on single internode cuttings from these stock plants was observed in relation to length of the internodes and the position on the vine (topophysis). The analysis indicated that the root number was primarily dependent on internode length which in turn was dependent on irradiance to stock plants and topophysis. The irradiance of 37 W m‐2 PAR was optimal for internode length and root number and the basal internode was the one which produced the greatest number of roots.
Photosynthesis in leaves of the juvenile and adult phase of ivy (Hedera helix)
Authors: BAUER HELMUT , BAUER ULRIKE
Published: April 2006

Abstract Photosynthetic and anatomical parameters of leaves from the juvenile and adult part of an ivy plant (Hedera helix L.) have been determined and compared with each other. Light‐saturated net photosynthesis (per unit leaf area) was about 1.5 times higher in adult leaves than in juvenile ones. The lower photosynthetic capacity of juvenile leaves was caused by a lower stomatal and especially a lower residual conductance to the CO2‐transfer. This corresponds with anatomical features of the leaves, i.e. lower stomatal frequency, fewer chloroplasts per cell, and – most important – thinner leaves, as well as with a less efficient photosynthetic apparatus measured as Hill reaction of isolated broken chloroplasts and activity of ribulose bisphosphate carboxylase. No differences in the respiration in light (relative to net photosynthesis) and in the CO2‐compensation concentration could be detected between the two leaf types. These observed anatomical and photosynthetic parameters of the juvenile and adult ivy leaves resemble those reported for shade and sun leaves, respectively, although the leaves investigated originated from the same light environment.
Responses of Melaleuca quinquenervia seedlings to flooding
Authors: GOMES A. R. SENA , KOZLOWSKI T. T.
Published: April 2006

Abstract Studies were conducted on effects of flooding for 15, 30, 60, and 90 days on morphological changes, stomatal aperture, water potential, and growth of seedlings of Melaleuca quinquenervia, a species often planted for reclamation of swamps. Flooding rapidly induced formation of many hair‐like adventitious roots as well as a few thick adventitious roots that originated on the original root system. Some adventitious roots also formed on submerged portions of the stem. Melaleuca seedlings were very tolerant of flooding as shown by only slight reduction in dry weight increment of shoots after 30 days of flooding in stagnant water. Although flooding for 60 or 90 days significantly reduced dry weight increment of leaves, dry weight increment of roots was not inhibited by any flooding treatment, reflecting both degeneration of some of the original roots and compensatory growth of adventitious roots. On certain days flooding induced stomatal closure on both adaxial and abaxial leaf surfaces. Extensive production of adventitious roots and some stomatal reopening after a critical period of flooding appeared to be important factors in the flooding tolerance of Melaleuca and are consistent with its aggressiveness and vigorous growth on wet sites.
Effect of calcium on sulfate uptake by barley roots
Authors: SKJELBREID EGIL , NISSEN PER
Published: April 2006

Abstract Sulfate uptake by excised roots of barley (Hordeum vulgare L.) was maximal in the presence of about 3x10‐3M CaCl2. Kinetic studies contraindicate a stoichiometric binding of calcium to the carrier for sulfate, in contrast to findings of Cuppoletti and Segel (Biochemistry 14: 471–4718, 1975) for the filamentous fungus Penicillium notatum. In barley, calcium affects the Km but not the Vmax for sulfate uptake, presumably by altering the conformation and, thereby, the affinity of the carrier. Calcium also affects the transition site for sulfate uptake.
Lectin‐mediated agglutination of plant protoplasts
Authors: FENTON C. ARIEL LOU , LABAVITCH JOHN M.
Published: April 2006

Abstract The ability of concanavalin A, soybean agglutinin and lectins from Pisum sativum and Bandeiraea simplicifolia to mediate the agglutination of protoplasts prepared from Nicotiana glauca, Zea mays, and Lactuca sativa was assessed. Pea lectin failed to mediate agglutination; the other lectins agglutinated the three cell types tested. A microtiter assay was used to assess the activity of the lectins. The three active lectins had different activities against each of the protoplast types tested.
Variation with age in the photosynthetic carbon fixation pattern by leaves of Amaranthus paniculatus and Oryza sativa: Change in the primary carboxylation but no shift from C4 or C3 pathway
Authors: RAGHAVENDRA AGEPATI S.
Published: April 2006

Abstract The pattern of photosynthetic carbon fixation by leaves of Amaranthus paniculatus L. (a C4 plant) and Oryza sativa L. (a C3 plant) varied with age. Younger leaves of A. paniculatus incorporated 14CO2 into malate and aspartate while senescent leaves fixed predominantly into phosphoglycerate (PGA) and sugar phosphates. Only developing leaves of O. sativa formed malate/aspartate whereas mature and senescent leaves produced PGA/sugar phosphates as the initial labelled products. Correspondingly the ratio of phosphoenolpyruvate/ribulose bisphosphate (RuBP) carboxylase activities was higher in younger leaves of A. paniculatus and developing leaves of O. sativa than in older leaves. However, pulse chase experiments revealed that the main donors of carbon to end products, irrespective of leaf stage, were C4 acids and PGA in A. paniculatus and O. sativa respectively. The results suggest that although an apparent change from initial β‐carboxylation to RuBP carboxylation occurs during leaf ontogeny in both the plants, the overall leaf photosynthesis remains C4 or C3. The high rate of 14CO2 incorporation into PGA/sugar phosphates by senescent leaves of A. paniculatus is suggested to be partly due to the increased intercellular spaces in their mesophyll, allowing greater access of CO2 directly to RuBP carboxylase in the bundle sheath.
Thigmomorphogenesis: Calibration of the parameters of the sensory function in beans
Authors: JAFFE M. J. , BIRO R. , BRIDLE K.
Published: April 2006

Abstract An instrument has been built which reproducibly exerts measured amounts of force in an up and down rubbing motion to bean plant stems (Phaseolus vulgaris L. cv. Cherokee Wax). The thigmostimulator has, for the first time, permitted an accurate determination of the relationship between the amount of mechanical stimulus or stress (MS) and the resulting elongation of the plant (E). Over the stress range used, the analyzed relationship is best expressed by the equation: E = m In MS + b, where m is the slope of the line and b is the E‐intercept. The sensory function is saturated at very low forces (e.g. 2 rubs at 3.59 N). Reciprocity between force and the number of stimuli holds only at low forces and numbers of stimuli (e.g. 12 rubs at 0.97 N to four rubs at 2.92 N). Analysis using linear regression and differential calculus reveals that for five 1‐cm rubs, the sensory system is saturated at 6 N and that there is a threshold of 0.3 N below which no response occurs. Using the thigmostimulator for calibration, two 1‐cm rubs given by hand are equivalent to a force of 4.41 ± 0.60 N. The thigmostimulator also allows equivalent calibration of other types of mechanical perturbations.
Light and ethylenediamine tetraacetic acid mediated differential effects of ammonium on nitrate reductase activity in maize seedlings
Authors: MEHTA PRATIMA , JAIN ABHA , SRIVASTAVA H. S.
Published: April 2006

Abstract Effect of ammonium on in vivo activity of nitrate reductase in roots, shoots and leaves of maize (Zea mays L.) seedlings was studied in relation to light/dark conditions and EDTA supply. Supply of 5 mM (NH4)2SO4 increased the steady state level of enzyme only in leaves and in light, while it had no effect in roots and shoots and in the dark. The substrate induction of enzyme was also little affected by 1 to 10 mM (NH4)2SO4 in roots and shoots. In the leaves the activity in the dark was either inhibited (minus EDTA) or stimulated (plus EDTA) by 5 to 10 mM (NH4)2SO4. The activity was stimulated in the light also in the presence of EDTA at higher concentrations of ammonium. When different concentrations of ammonium were supplied without any exogenous nitrate in the light, the enzyme activity increased at low concentration and was either inhibited or unaffected at higher concentrations depending upon the tissue used. Supply of EDTA with ammonium modified its effect to some extent. It is suggested that the effect of ammonium on nitrate reductase activity depends upon the tissue used and the effective concentration of the ammonium.
Relations polyphenols‐croissance: Lignification et limitation de croissance chez Lycopersicum esculentum
Authors: Et GÉRARD MARIGO , BOUDET ALAIN M.
Published: April 2006

Abstract Polyphenols and growth – Lignification and limitation of growth in Lycopersicum esculentum.

When fed with quinic acid, young tomato seedlings (Lycopersicum esculentum Mill. cv. St. Pierre) exhibited reduced growth and marked changes in cell wall composition: cellulose concentrations decreased whereas those of lignin increased. Exogenously supplied growth substances (IAA, GA3) affected both the size of the plants and the lignification process: IAA treatments resembled quinic acid induced modifications with regard to both size and lignification: GA3 applied to quinate treated plants counteracted the effects of this compound by reducing the lignin content and improving the growth. The possible effect of abnormal lignification as a limiting factor in cell growth is supported by the characterization of lignins in tissues different from xylem.
Isolation and properties of a lectin from the roots of Pisum sativum (Garden pea)
Authors: GATEHOUSE JOHN A. , BOULTER DONALD
Published: April 2006

Abstract The roots of pea (Pisum sativum L. ev. Feltham First) seedlings contained haemagglutinating activity and a protein which reacted with antibodies directed against pea seed lectin. This protein was shown to be present on the surface of root hairs and in the root cortical cells by immunofluorescence. Lectin (haemagglutinin) was purified from pea seedling roots by both immunoaffinity chromatography and affinity chromatography on Sephadex G‐100. The pea root lectin was similar to the seed lectin when analysed by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis, and was antigenically identical: however, the isoelectric focussing band patterns of the proteins differed. The sugar specificity of the root lectin differed from that of the seed lectin, and the haemagglutinating activity of the root lectin was less than the seed lectin. These results are discussed with reference to the hypothesis that lectins mediate in the symbiotic association of legume and Rhizobium through their carbohydrate‐binding properties.
Effects of potassium and gibberellic acid on stem growth of whole sunflower plants
Authors: DE LA GUARDIA MANUEL D. , BENLLOCH MANUEL
Published: April 2006

Abstract The effects of gibberellic acid (GA3) on whole sunflower (Helianthus annuus L.) plants grown at three potassium (K) levels (0.0, 0.5 and 5.0 mM) were studied. A tenfold increase in the length of the first internode was observed when plants grown without K were treated with GA3. The uneven K distribution along the plant (higher K content in the higher internodes) was enhanced by GA3 treatment. Gibberellic acid increased the content of reducing sugars, especially in K‐deficient plants. An increase in the K level in the nutrient solution resulted in a decrease of the osmotic potential of stem segments. Osmotic potential differences within the elongating first internode were increased by GA3 treatment.
Electrophysiological factors in the influence of nitrate and ammonium ions on calcium uptake and translocation in tomato plants
Authors: MACKLON A. E. S. , SIM A.
Published: April 2006

Abstract Tomato plants (Lycopersicon esculentum Mill. cv. San Marzano), grown in dilute nutrient solutions containing (in meq ˙ 1‐1) 0.5 NaNO3, 0.5 NH4NO3 or 0.25 (NH4)2 SO4 as the nitrogen source, were detopped for collection of xylem sap and measurement of trans‐root electrical potentials. The plant parts and the xylem exudate were subsequently analysed for mineral content. The commonly observed effects of NH4+ were noted, including reduction of calcium concentration in the xylem sap, and of calcium content in stems and leaves, compared with NO3‐fed plants. This effect was attributed principally to the less negative trans‐root electrical potential measured in NH4+‐fed plants, and the resultant reduction of inward driving force on passively moving divalent cations.
Selectivity of diclofop‐methyl between wheat and wild oat: growth and herbicide metabolism
Authors: DONALD W. W. , SHIMABUKURO R. H.
Published: April 2006

Abstract Growth of the second leaf of susceptible wild oat (Avena fatua L.) was inhibited within 2 days after treatment with the herbicide, diclofop‐methyl, in the 1‐1/2 leaf stage. Leaf growth of resistant wheat (Triticum aestivum L.) was unaffected by diclofop‐methyl. In wild oat. chlorosis developed 1 day after leaf growth was inhibited. Foliar absorption of diclofop‐methyl was similar between wild oat and wheat with 67 and 61% of the recovered radioactivity from [14C]diclofop‐methyl being absorbed by wild oat and wheat, respectively, after 4 days. Wild oal was equally sensitive to the methyl ester and acid forms of the herbicide when the compounds were injected into the stem. Wheat was unaffected by both forms when treated similarly. Very little diclofop‐methyl and diclofop (combined total of 10 to 12% in wild oat and 5 to 7% in wheat) remained in plant tissues 2 days after leaf treatment in both susceptible and resistant plants. Therefore, the active form of the herbicide must inhibit growth of susceptible plants very rapidly and at relatively low concentrations. Diclofop‐methyl was rapidly hydrolyzed to diclofop by wild oat and wheat. Wild oat predominantly conjugated diclofop to an ester conjugate but wheat hydroxylated the 2,4‐dichlorophenyl ring and formed a phenolic conjugate. The formation of the different conjugates between wild oat and wheat was the most significant difference in metabolism between the two species. Nearly 60 and 70% of the methanol‐soluble radioactivity was present as water‐soluble conjugates in wild oat and wheat, respectively, 4 days after treatment.