bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature and Humidity Effects on Net Photosynthesis and Transpiration of Citrus
Authors: KHAIRI MOHAMED M. A. , HALL ANTHONY E.
Published: April 2006

Maximum rates of net photosynthesis for Citrus sinensis (L.) Osbeck and Citrus paradisi Macf. cultivars were observed at the lowest temperature (22°C) under which these subtropical species were examined. Net photosynthesis decreased with higher temperatures or greater vapor pressure differences between leaf and air. The reduction in net photosynthesis due to higher temperatures was associated with reductions in mesophyll conductance to CO2; whereas, the effects of greater vapor pressure differences on net photosynthesis were associated with changes in total leaf conductance to water vapor. Actual water‐use efficiency was reduced at higher temperatures and greater vapor pressure differences, but intrinsic water‐use efficiency, calculated for a constant vapor pressure difference, increased with increases in vapor pressure difference indicating a possible adaptive mechanism for conditions of high evaporative demand. Day‐today increases in net photosynthesis, total leaf conductance to water vapor and mesophyll conductance were observed as plants were subjected to the same temperature and humidity treatments on progressive days. Growing plants under higher irradiances increased their photosynthetic rates and mesophyll conductance to CO2 but leaf conductance to water vapor was unaffected by irradiance pretreatment. Consequently, acclimation to radiation can only account for a small part of the day‐to‐day changes in gas exchange. Other possible explanations for these day‐to‐day changes were discussed. Significant differences were not observed among trees of ‘Campbell Valencia’ orange, ‘Parent Navel’ orange and ‘Frost Marsh’ grapefruit in responses of net photosynthesis and leaf conductance to temperature and humidity.
Comparative Studies of Net Photosynthesis and Transpiration of Some Citrus Species and Relatives
Authors: KHAIRI MOHAMED M. A. , HALL ANTHONY E.
Published: April 2006

Comparisqns were made between ‘Campbell Valencia’ orange (Citrus sinensis (L.) Osbeck), and ‘Gabon Cherry‐orange’ (Citropsis gabunensis (Engl.) Swing.), ‘Frost Lisbon’ lemon (Citrus limon (L.) Burm. f.) and ‘Eremolemon’ (Eremocitrus glauca (Lindl.) Swing. ×Citrus limon (L.) Burm. f.) and between diploid and autotetraploid ‘Lisbon’ lemons with respect to the influences of temperature and humidity on net photosynthesis and transpiration.

Net photosynthesis, leaf conductance to water vapor and water‐use‐efficiency of Citropsis gabunensis were lower than with Citrus sinensis.‘Eremolemon’ had higher net photosynthesis and higher water‐use‐efficiency than ‘Lisbon’ lemon, but only small differences were observed between the two species in leaf conductance to water vapor. Small, nonsignificant, differences were observed between diploid and tetraploid ‘Lisbon’ lemons in responses of net photosynthesis and leaf conductance to temperature and humidity. Temperatures above 30°C and increases in vapor pressure difference caused declines in net photosynthesis and increases in vapor pressure difference resulted in decreases in leaf conductance to water vapor by all of the species used in these studies.
Adventitious Root Formation Induced by Gibberellic Acid and Regulated by the Irradiance to the Stock Plants
Authors: HANSEN JÜRGEN
Published: April 2006

Pea plants (Pisum sativum L. cv. Alaska) were grown from seeds for eleven days at different irradiances. Cuttings were then excised and rooted at 16 W × m−2. Gibberellic acid (GA3, 10−11 to 10−3M) was applied to the cuttings immediately after excision.

Cuttings from stock plants grown at the highest level of irradiance (38 W × m−2) formed the lowest number of roots. An increasing number of roots per cutting was obtained by decreasing the irradiance to the stock plants. In cuttings from stock plants grown at low irradiances, low concentrations of GA3 (10−8 and 10−7M) promoted root formation further. No effect on rooting by these GA3 concentrations was observed when applied to cuttings originating from stock plants grown at the high irradiances. Root formation in all cuttings was inhibited by GA3 at concentrations higher than 10−6M. The degree of inhibition by GA3 was influenced by the irradiance pretreatment and was increased with an increase in the irradiance during the stock plant growth.

Seeds from different years produced cuttings with different response patterns regarding the irradiance and GA3 effects on rooting.
The Effect of Various Alkaline Salts on the Glycolate Oxidase of Salicornia europaea and Pisum sativum in vitro
Authors: AUSTENFELD FRANZ‐ARNOLD
Published: April 2006

The response of glycolate oxidase from shoots of Salicornia europaea L. and from leaves of Pisum sativum L. to salt treatment during assay was studied by DCPIP reduction and O2 uptake. In Pisum there was found up to five times more glycolate oxidase activity per gram fresh weight than in Salicornia. However, the calculation of the specific activity pointed out that this result was caused only by the high level of enzyme protein in Pisum, and that specific activity from both species was of equal size.

By the DCPIP method it was shown that in test media containing up to 1.0 M NaCl or KCl glycolate oxidase of Salicornia was of equal size compared with the control (medium without additional salts). With 2.0 M NaCl or KCl the activity decreased by about 80 and 30% respectively. Glycolate oxidase of Pisum was somewhat more salt sensitive. 1.0 M NaCl or KCl reduced the activity by about 35%. In the presence of 2.0 M NaCl or KCl the enzyme activity from Pisum was inhibited to about 80 and 60% respectively. By substituting sulfates for chlorides the activity of glycolate oxidase from both Salicornia and Pisum was stimulated strongly. 1.5 M Na2SO4 and 0.5 M K2SO4 (both are saturated solutions) caused an increase of glycolate activity from Salicornia of about 225 and 185% respectively, and from Pisum of about 50 and 30% respectively.

Studying the response of glycolate oxidase to salt treatment by O2 uptake one must establish that with this method the degree of inhibition of enzyme activity at higher salt concentrations was always more severe than with dye reduction. Addition of 1.0 M NaCl or KCl to the assay medium caused an inhibition of glycolate oxidase activity from Salicornia of about 50% and from Pisum of about 60%. 2.0 M NaCl or KCl reduced the enzyme activity of both Salicornia and Pisum to nearly 10% of control activity. Furthermore, in contrast to DCPIP reduction no stimulating effect of sulfates on glycolate oxidase activity was detectable. Indeed, the inhibitory effect of sulfates was very slight. 1.0 M Na2SO4 caused a mean inhibition of glycolate oxidase activity of only 15% with both species, and in the presence of 1.5 M Na2SO4 50% of control activity was measured. At maximal K2SO4 concentrations (0.5 M) glycolate oxidase from both Salicornia and Pisum was also unaffected.

It is supposed that the described salt tolerance of glycolate oxidase in vitro, possibly is due to an adaptation of the enzyme to high salt levels within peroxisomes in vivo.
The Intracellular Location of Abscisic Acid in Stressed and Non‐Stressed Leaf Tissue
Authors: LOVEYS B. R.
Published: April 2006

The intra‐cellular location of ABA was investigated in relation to its sites of synthesis. Chloroplasts were isolated from stressed and non‐stressed spinach leaves and their ABA content determined. Virtually all of the ABA from non‐stressed leaves was contained in the chloroplasts compared with only a small fraction of ABA isolated from stressed leaves. Chloroplasts prepared from turgid leaves and subsequently lysed in vitro retained most of their ABA and phaseic acid (PA) complement but this was removed with organic solvents.

While the possibility of extra‐chloroplastic synthesis cannot be discounted the data indicate that stress‐induced ABA synthesis occurs in the chloroplast and that the ABA readily migrates from there to other parts of the plant.
Peroxidase and α‐Amylase Activities in Relation to Germination of Dormant and Nondormant Wheat
Authors: GASPAR THOMAS , WYNDAELE RITA , BOUCHET MIREILLE , CEULEMANS ETIENNE
Published: April 2006

Germination capacity, and α‐amylase production in relation to the peroxidase and isoperoxidase activities in the grains of three varieties of wheat have been analysed and compared. A high percentage of germination and α‐amylase producation at 25°C are associated with low peroxidase activity of the isolated embryo. This correlation is lacking when the intact grain is considered. A 2‐day treatment at 4°C which further increases the percentage germination and enhances α‐amylase synthesis, lowers the activity of peroxidase in the embryos. A general decrease in activity of all the isoenzymes is observed.

Based on the above data and on differences in the activity of the most cathodic isoperoxidasic bands, a hypothesis is put forward which suggests that a sufficiently low peroxidase activity and a minimum auxin level of the embryo are responsible for the onset of germination.
Isopropyl m‐Chlorocarbanilate and Its Hydroxylated Metabolites: Their Effects on Cell Suspensions and Cell Divison in Soybean and Carrot
Authors: DAVIS D. G. , HOERAUF R. A. , DUSBABEK K. E. , DOUGALL D. K.
Published: April 2006

Hydroxylated metabolites of isopropyl m‐chlorocarbanilate (chlorpropham) are found in intact soybean plants (Glycine max Merr.). The metabolites are isopropyl 2‐hydroxy‐5‐chloro‐carbanilate (2OH) and isopropyl 3‐chloro‐4‐hydroxycarbanilate (4OH). The phytotoxicity of these metabolites and chlorpropham was tested in cell suspensions and roots of intact soybean seedlings and cell cultures of carrot (Daucus carota L.). The growth of soybean cell suspensions was inhibited with 50 μM chlorpropham. Ten μM chlorpropham usually slowed initial growth of the cultures while 5 μM and 0.1 μM chlorpropham had no effect. The 2OH and 4OH metabolites had no significant effect on dry weight over the same concentration range. Some metabolism of chlorpropham, 2OH and 4OH occurred during 6 and 48 h of incubation with soybean cells. The results are interpreted to mean that all three analogs penetrated into the cells, were metabolized, and some of the metabolites excreted back into the medium. Mitotic index studies of intact 3‐day‐old soybean roots showed that 2OH inhibited mitosis to a greater extent than chlorpropham, whereas 4OH produced only a slight and insignificant reduction compared to controls. Chlorpropham, 2OH and 4OH (at 50 μM) all reduced the growth of wild carrot cultures grown in the presence or absence of 2,4‐D. Therefore, hydroxylation of chlorpropham at the 2′ or 4′ positions of the 5′ chlorinated benzene ring is not sufficient to render the compound nonphytotoxic in all plant systems.
Evidence for DNA Polymerase‐α and ‐β Activity in Sugar Beet
Authors: TYMONKO JOHN M. , DUNHAM VALGENE L.
Published: April 2006

DNA polymerase preparations from incubated sugar beet (Beta vulgaris) root tissue exhibited multiple activities following DEAE‐cellulose chromatography and glycerol density gradient centrifugation (600‐fold purification). The two major polymerase activities eluted from DEAE‐cellulose differed in heat lability, pH and Mg2+ optima, and in response to ethanol, p‐hydroxymercuribenzoate, and N‐ethylmaleimide. Further purification by glycerol gradient centrifugation indicated the presence of a low molecular weight molecule (3.4 S), heterogeneous larger molecules (6.2, 6.8 S), and apparent aggregates (11–11.5 S). This investigation indicates similarities between sugar beet polymerases and the small (β) and large (α) molecular weight polymerases from mammalian systems.
Potassium and Rubidium Interaction in Their Absorption by Bean Leaf Slices
Authors: JACOBY BENJAMIN , NISSEN PER
Published: April 2006

Mesophyll cells of leaf slices of bean (Phaseolus vulgaris L.) absorb six to ten times more K+ than Rb+ from 0.1 mM single chlorides of these cations. Absorption of 42K+ from 0.1 mM42KCl is much more inhibited by low concentrations of Rb2SO4 than by K2SO4. The isotherm for K+ absorption is biphasic in the range 0.1–1.1 mM, and K+ is more effective than Rb+ in causing transition from phase 1 to phase 2.
Diurnal Fluctuations in Relative Water Content, Nitrate Reductase and Proline Content in Water‐stressed and Non‐stressed Wheat
Authors: RAJAGOPAL V. , BALASUBRAMANIAN V. , SINHA S. K.
Published: April 2006

Diurnal variations in relative water content (RWC), nitrate reductase (NR) and proline content (PC) were studied at 3 h intervals during a 24 h cycle in the flag leaf of wheat (Triticum vulgare, v. Kalyansona) grown under stressed and non‐stressed conditions.

RWC was lower in stressed plants than in non‐stressed ones throughout the 24 h period. Although it was lowest at 12 h, it recovered by 15 h. Non‐stressed plants maintained higher NR activity compared to those under stress. The enzyme activity during night was about the same as during day time in both types of plants. Compared to non‐stressed plants, stressed ones had lower NO3− content. Proline accumulation occurred under stress conditions and had a maximum at 12–15 h. Non‐stressed plants exhibited higher PC during night than day time.

Changes in temperature and relative humidity were noted during the period and their influence on RWC, NR and proline was discussed.
Development of Asparagus plumosus Shoot Tips Grown in vitro
Authors: FONNESBECH MOGENS , FONNESBECH ANNE , BREDMOSE NIELS
Published: April 2006

Lateral shoot tips from young Asparagus setaceus (Kunth) Jessop (syn. A. plumosus Baker) shoots were grown on a modified Murashige and Skoog medium. Tips from 5 to 20 mm lateral shoots had significantly better growth and development than tips from lateral shoots (2 mm) still covered by leaf‐scale. The optimum temperature for growth and development of the explants was 17 to 24°C. The initial growth was fast at 24°C but stopped after about 4 weeks. At 17°C the growth was slow but in return the cultures continued to grow. Kinetin was necessary for growth. Without any kinetin all cultures died. Optimum growth was found with 2 mg/l kinetin. There was no growth at all with IAA alone. A low IAA concentration had no effect, but at high concentrations IAA inhibited the kinetin induced growth.
Devenir de la putrescine‐1,4‐14C chez Glycine max
Authors: LE RUDULIER DANIEL , GOAS GABRIELLE
Published: April 2006

Fate of Putrescine‐1,4‐14C in Glycine max

Putrescine‐1,4‐14C was supplied to young decotylized Glycine max (L.) Merr. cv. Chippewa plants growing under aseptic conditions on a liquid medium with nitrogen supplied either as ammonium chloride or nitrates. Whatever the source of nitrogen the diamine was quickly transformed to γ‐aminobutyric acid, succinic acid and malic acid; only a very minor part was utilized for the synthesis of polyamines. In the presence of ammonium chloride the putrescine catabolism may be slower than in the presence of nitrates. The results are explained by a weak isotopic dilution or by a diamine oxidase activity lower in “ammonium” plants than in “nitrate” plants; the two causes might co‐exist. The possibility of a diamine compartmentation has to be considered.
Influence of S‐ethyl Dipropylthiocarbamate (EPTC) on the Fatty Acid Composition of Wheat Leaf Galactolipids
Authors: KARUNEN P. , ERONEN L.
Published: April 2006

Winter wheat (Triticum sativum L. cv. Nisu) was grown in sand which contained 0, 0.25, 0.5 and 1.0 mg S‐ethyl dipropylthiocarbamate (EPTC) per kg air dry sand. The galactolipids of leaves of 21‐day‐old seedlings were isolated by preparative thin layer chromatography. The fatty acids of the mono‐ and digalactosyl diglycerides were analysed by gas liquid capillary chromatography. The major fatty acids of the wheat leaf galactolipids were palmitic, palmitoleic, stearic, oleic, vaccenic, linoleic and linolenic acids (in the monogalactosyl diglyceride fraction of untreated plants 22.5, 2.4, 3.1, 5.2, 2.5, 51.1 and 1526.6 μg and in the digalactosyl diglyceride fraction 108.8, 2.3, 10.4, 9.9, 8.2, 42.3 and 1120.7 μg/g leaf fresh weight, respectively). Total fatty acid content of the mono‐ and digalactosyl diglyceride fractions was decreased by 85 and 87%, respectively, at 1 mg EPTC/kg sand, while decrease in the fresh weight of the leaves was 79%. The content of linoleic and linolenic acids/g fresh weight of the leaves was decreased in the monogalactosyl diglyceride fraction by 27 and 43%, respectively, while the content of all other fatty acids was increased. In the digalactosyl diglyceride fraction the content of both linoleic and linolenic acids/g leaf fresh weight was decreased by 55%. The content of palmitic and vaccenic acids was also decreased, whereas the content of other fatty acids remained at the level of the untreated samples. The general quality of the fatty acids in the mono‐ and digalactosyl diglyceride fractions was altered slightly by EPTC.
Regulation of Internodal Extension in Avena Shoots by the Inflorescence, Nodes, Leaves, and Intercalary Meristem
Authors: KONING ROSS , TKACZYK ANNE , KAUFMAN PETER B. , PHARIS RICHARD P. , MORF WILLIAM
Published: April 2006

It has been found in recent studies that the inflorescence and nodes (node‐pulvini) are the primary sources for native gibberellins in the Avena shoot, and that GA3 is the predominant gibberellin in the inflorescence. In the present work, linear growth of next‐to‐last internode is drastically reduced by removal of the inflorescence and last leaf. This growth is completely abolished when the nodes are also excised. It is restored fully by the addition of GA3 when the nodes are present, and restored only partially when the nodes are deleted. Internodal growth in Avena stem segments with basal node present is also restored by native GA3‐like substances extracted from Avena inflorescences and partially purified by silica gel partition column chromatography. Evidence from these studies, taken in toto, indicates that the inflorescence, nodes, and leaves supply gibberellins, leaves supply substrate, and nodes modulate the gibberellin growth response in next‐to‐last Avena internodes.
Sugar and Amino Acid Content of Poa pratensis Infected with Ustilago striiformis and Urocystis agropyri
Authors: HODGES CLINTON F. , ROBINSON PHILIP W.
Published: April 2006

Leaf and root tissues of Poa pratensis L. showing distinct morphological changes associated with infection by Ustilago striiformis (West.) Niessl var. poae (stripe smut) or Urocystis agropyri (Pruess) Schroet. (flag smut) were analyzed for total soluble sugars and free amino acids. Decreases in the quantity of soluble sugars in stripe‐smutted plants were not significant, indicating that the presence of U. striiformis sori in leaf tissue does not interfere with photosynthesis of the host. Severe decreases in the quantity of soluble sugars in flag‐smutted plants suggest that U. agropyri either directly impairs photosynthesis or effectively metabolizes the photosynthate. Both pathogens caused significant decreases in total free amino acids in leaf and root tissues. The negligible decrease in soluble sugars in stripe‐smutted plants was associated with a disproportionate decrease in free amino acids, suggesting that the pathogen either metabolizes amino acids or inhibits their synthesis. The severe decrease in amino acids in leaves and roots of U. agropyri‐infected plants is believed due to carbohydrate starvation. It is probable that morphological changes in U. agropyri‐infected plants, including reduced branching, dwarfed leaves and root systems, and the inability to produce inflorescences, are probably the direct result of severely reduced levels of sugars and amino acids. The reduced branching, somewhat smaller root systems, and inhibition of inflorescence production on plants infected by U. striiformis probably are associated to some extent with decreases in amino acids. The upright elongated leaves of U. striiformis‐infected plants, however, cannot be attributed to the decrease in amino acid content and are suggestive of hyperauxiny.
Uptake of Iodide by Excised Bean Roots
Authors: KAUFHOLZ H. , REINIGER P.
Published: April 2006

In view of eventual hazards of I‐129 from nuclear fuel elements, the uptake of iodide by excised 10‐day‐old bean roots (Phaseolus vulgaris L. cv. Berna) was studied using a radiotracer technique. The uptake in the range of 5 × 10−9 to 10−6M iodide can be represented by a single phase obeying Michaelis‐Menten kinetics.
Cell Suspension and Callus Culture from Somatic Tissue of Maize
Authors: OSWALD T. H. , NICHOLSON R. L. , BAUMAN L. F.
Published: April 2006

Cell suspension and callus cultures from somatic tissue of inbred lines of maize (Zea mays L.) were cultured on media that were defined via modification of a Linsmaier and Skoog preparation. Germlings incubated on the primary medium originally employed required long‐term incubation for callus induction. Modification of the primary medium with high levels of iron and (ethylene dinitrillo)tetraacetic acid (EDTA), B vitamin amendments and vitamin E, shortened incubation by 75% and nearly doubled the percentage of germlings which produced callus. Callus did not remain viable in subcultures to the secondary medium originally employed, whereas a preparation, developed via modification of the original secondary medium, enabled perpetuation of callus through repeated subculture. Modification with high levels of iron and EDTA, plug B vitamins and vitamin E, with decreased concentrations of five inorganic salts, suppressed aberrant organogenesis and stabilized culture growth as viable callus. Similar modification, with the exception that EDTA was omitted, was employed for the development of a liquid medium. Tonicity of the medium was adjusted with a lowered level of sucrose, with the liquid further modified by addition of acetate. Upon development of this liquid, maize became the sixth monocot species for which somatic cells remain viable through repeated subculture in liquid suspensions.
Thigmonastic Coiling of Tendrils of Passiflora quadrangularis is Not Caused by Lateral Redistribution of Auxin
Authors: JUNKER STEFFEN
Published: April 2006

The effect of thigmotropic stimuli on the distribution of exogenously applied indoleacetic acid in intact tendrils of Passiflora quadrangularis L. has been investigated. Tips of tendrils were dipped in solutions of IAA‐2‐14C for 12 h and subsequently stimulated by exposure to carbon dioxide or mechanically by rubbing. The content of 14C in dorsal and ventral halves was analysed before, during and after coiling. Our experiments failed to detect any difference from the initial dorsal: ventral ratio of 14C (44:56) as a possible consequence of stimulus or of coiling. This suggests that thigmotropic curvature is not dependent on lateral movement of auxin, supporting a theory of a built‐in asymmetrical reaction of the tissues to equal amounts of auxin and CO2, respectively.
Chlorate Toxicity and Nitrate Reductase Activity in Tomato Plants
Authors: HOFSTRA J. J.
Published: April 2006

Chlorate damage was studied in tomato plants (Lycopersicum esculentum cv. Moneymaker) that were supplied with a nitrogen‐free nutrient solution or with a nutrient solution, containing either nitrate or ammonium as a nitrogen source. Damage was low in ammonium‐fed plants and high in nitrate‐fed plants and in nitrogen‐less plants. Nitrate reductase activity could be detected in all treatments, although the activity was highest in the nitrate‐fed plants.

The hypothesis that chlorate can be used as a substrate by the enzyme nitrate reductase in higher plants, was studied and proved to be true for the tomato plants, as was found earlier for Escherichia and Chlorella. The affinity of the enzyme for chlorate was lower than for nitrate, the Km being 4 mM and 0.15 mM respectively. Induction of the enzyme by chlorate could not be detected. The enzyme activity was lowered in leaf discs after a 7 h treatment with chlorate and the inhibition was proportional to the chlorate concentration of the medium.

The results were discussed in terms of competition between nitrate and chlorate at the uptake and the enzyme site and with regard to a possible influence of chlorate on synthesis and breakdown of the enzyme.
Effect of NaCl on the in vitro Activity of Malate Dehydrogenase in Salt Marsh Halophytes of the U.S.
Authors: CAVALIERI ANTHONY J. , HUANG ANTHONY H. C.
Published: April 2006

The in vitro effect of NaCl on NAD‐malate dehydrogenase (E.C. 1.1.1.37; MDH) from desalted extracts of roots and leaves of six salt marsh halophytes was investigated. The plants, all native and important constituents of the salt marshes of the east coast of the U.S., included Spartina alterniflora Loisel., Spartina patens (Aiton) Muhl., Distichlis spicata (L.) Greene, Juncus roemerianus Schleele, Salicornia virginica L., and Borrichia frutescens (L.) DC. In the leaf extracts of all species except Borrichia frutescens, the MDH activity was slightly stimulated by NaCl at concentrations around 0.05 M at optimal pH (8.0–8.5) and was reduced by NaCl in higher concentrations. MDH activity in the leaf extract of Borrichia frutescens was more salt‐tolerant and maximal activity occurred around 0.25 M NaCl at optimal pH (7.0). Even though similar pH optimums for activity were exhibited in the root and leaf extracts of each species, the MDH activity in the root extract was more salt‐tolerant than that in the leaf extract. NaCl at concentrations up to 0.1 M stimulated the MDH activity in the root extracts of all species except that of Borrichia frutescens, which had an optimal activity in 0.5 M NaCl. In the root and leaf extracts of Borrichia frutescens, the activity of cytosol MDH was much more salt‐tolerant than that of the mitochondrial MDH. A shift of the optimal pH to more acidic values with increasing concentrations of NaCl was noted in the extracts of all the species except Borrichia frutescens. The action of NaCl on MDH activity appeared to be a general ionic effect as judged by the response of the enzyme activity in the presence of iso‐ionic concentrations of other salts and isoosmotic mannitol. Thus, the response of the MDH from five of the salt marsh plants to NaCl is similar to that of glycophytes. However, Borrichia frutescens possesses a salt‐tolerant MDH that has optimal activity in a salt concentration as high as that of the environment.
A Revised Medium for Growth of Pea Mesophyll Protoplasts
Authors: VON ARNOLD SARA , ERIKSSON TAGE
Published: April 2006

The nutrient requirements of mesophyll protoplasts from Pisum sativum L. cv. Timo have been investigated and a synthetic and completely defined medium has been designed. A high calcium concentration (12 mM) stimulated both protoplast survival and cell division. The content of iron and zinc was also critical. Additions of nicotinic acid, pyridoxine and thiamine were necessary. The protoplast growth was enhanced when some amino acids were included in the medium. An absolute requirement for auxin and cytokinin was shown.

In the revised medium about 90% of the isolated protoplasts survived and formed a cell wall. The first divisions were observed after 5 days and after 1 week 10–20% of the cells had divided at least once.
Adaption to Photosynthesis and Diurnal Oscillation of Root Respiration Rates for Lolium multiflorum
Authors: HANSEN G. K.
Published: April 2006

Continuous measurements of CO2‐release from intact roots of Lolium multiflorum growing in nutrient solution were carried out during 3–7 weeks. Periods of days with high level of irradiance and periods with low level alternated. Root respiration rate was found to depend on photosynthesis. The change in root respiration, induced by change in photosynthesis, was delayed. The root respiration rate showed diurnal fluctuations with two characteristic peaks occurring 4–6 and 14–16 hours after onset of the photoperiod. The amplitudes increased with increasing photosynthesis. The frequencies were independent of the length of photoperiod, when this varied between 8 and 16 hours. The fluctuations are discussed in relation to diurnal fluctuations in protein synthesis.
The Effect of Different Portions of the Sunlight Spectrum on Ethylene Evolution in Peach (Prunus persica) Apices
Authors: EREZ AMNON
Published: April 2006

Exposure of peach plants to the blue plus far‐red (B/FR) portions of the sunlight spectrum caused a rapid rise in ethylene evolution from their apices. Two days were enough to produce a significant rise in ethylene evolution relative to blue without far‐red or to neutral shade. Maximal level of ethylene evolution in the B/FR light, more than eight times that of the blue or the neutral shade, was reached after four days of exposure. A higher endogenous ethylene content was also found under B/FR relative to blue or to neutral shade conditions. The level of ethylene evolution from peach apices was correlated with their arrested growth as observed a few days later.

Exposure of peach plants to dense leaf shade, under the canopy of a big avocado tree, enhanced ethylene evolution from their apices, relative to unfiltered sunlight and to neutral shade. It was suggested that the rise in ethylene evolution in both B/FR and leaf shade conditions resulted from a high far‐red: red ratio. Ethylene was further suggested to act as a mediator of photomorphogenetic regulation of vegetative development in far‐red‐rich tree shade.
Absorption des acides amines par les lutoïdes du latex d'Hevea brasiliensis
Authors: HANOWER P. , BRZOZOWSKA J. , NGORAN M. NIAMIEN
Published: April 2006

Absorption of Amino Acids by Lutoids from the Latex of Hevea brasiliensis.

The latex of Hevea brasiliensis is a fluid protoplasm containing organelles with a single membrane that are called lutoids. They are microvacuoles of a lysosomal character. The intact lutoids can easily be isolated in an isotonic medium by the usual procedures of cellular fractionation.

Previous studies have shown the existence of a compartmentation of the free amino acids in latex. While acidic components dominate in the cytoplasmic serum, the lutoid serum contains mainly basic components. These findings, as well as the part played by the lutoids in the latex flow and in the process of latex coagulation, led the authors to study the penetration of acidic, neutral and basic amino acids into the lutoids. Labelled amino acids were used for the purpose. Special interest was given to the uptake of lysine, which is transported into the lutoids against a concentration gradient in the absence of a metabolic energy source. The process is linear for at least 30 min and follows Michaelis–Menten kinetics as a function of the lysine concentration. The uptake is strictly temperature and pH dependent. It increases in the presence of ATP. Lysine uptake by lutoids is also increased by application of Ethrel, ethylene generator, to the bark of tapped trees. 2,4‐Dinitrophenol (2,4‐DNP), ammonium chloride and N‐ethylmaleimide (NEM) inhibit the influx. Neutral l‐amino acids do not affect the uptake of l‐lysine, while l arginine inhibits lysine transport competitively. d‐lysine is without effect on l‐lysine uptake by lutoids. Under conditions used in this study no lysine efflux is observed. A mechanism governing the penetration of basic amino acids against a concentration gradient is discussed, and the possible role of a proton gradient is suggested.
Influence of Light and Temperature on Photosynthesis and Transpiration in Some C3 and C4 Vegetable Plants from Kenya
Authors: IMBAMBA S. K. , TIESZEN LARRY L.
Published: April 2006

Potted vegetable plants of Amaranthus lividus, Gynandropsis gynandra and Crotalaria brevidens were grown outside under normal tropical conditions and rate of photosynthesis and transpiration were determined simultaneously in attached leaves under a range of leaf temperatures and irradiances. Photosynthetic rates were consistently higher in G. gynandra than in A. lividus and C. brevidens. However, in C. brevidens and G. gynandra the leaf resistances were lower and transpiration rates were higher than those in A. lividus.

The results on optimum temperature requirements for maximum rates of CO2 fixation, coupled with data on CO2 compensation points and leaf anatomy provided clear evidence that G. gynandra and A. lividus are C4 species, while C. brevidens is a C3 species. The differential effects of light intensity and temperature on stomata and mesophyll resistances in C3 and C4 species are discussed in relation to rates of photosynthesis and transpiration.
Čerenkov Counting of 24Na in Suspension Cultures — an Economical Use of Scintillation Apparatus for Studying Ion Exchange
Authors: PENNARUN A. M. , KOVOOR A. , HELLER R.
Published: April 2006

The feasibility of using Čerenkov radiation to estimate 24Na in the study of ion exchange in cell suspension cultures of Acerpseudoplatanus has been investigated. Some practical procedures for preparing samples and counting have been proposed according to the particular need of the experiment and the desired degree of counting efficiency.
Morphactin and Adventitious Root Formation in Pea Cuttings
Authors: KHAN A. RAUF , ANDERSEN A. SKYTT , HANSEN JÜRGEN
Published: April 2006

Stock plants of pea (Pisum sativum L. cv. Alaska) were grown at different controlled levels of irradiance (4, 16 or 38 W m−2) for 11 days from sowing. Morphactin (CFM, methyl‐2‐chloro‐9‐hydroxy‐fluorene‐9‐carboxylate) was applied to the apex of the stock plants 3 days before cuttings were excised. The cuttings were rooted at 16 W m−2. High levels of morphactin (>5 × 10−3 mg l−1) inhibited root formation in the cuttings. Low concentrations of CFM (5 × 10−5 mg l−1) promoted the formation of adventitious roots in cuttings from plants grown at all three levels of irradiance, with the most pronounced effect in cuttings from 4 W m−2. Measurements of ethylene evolution by CFM‐treated plants 3 days after application, revealed a stimulatory effect on ethylene production by high CFM concentrations.
Occurrence and Heterogeneity of Chymotrypsin Inhibitors in Vegetative Tissues of Barley
Authors: KIRSI MARKKU , MIKOLA JUHANI
Published: April 2006

Inhibitors of chymotrypsin and the alkaline proteinase of Aspergillus oryzae were present in the shoots of barley seedlings and weak activities were also detected in the shoot tops of 6‐week‐old plants. Treatments which induce inhibitor formation in tomato and potato leaves had no effect when tested on mature leaves, seedlings, or young tillers of barley.

Fractionation experiments with isoelectric focusing showed that the barley leaves contained several proteinase inhibitors acting on both chymotrypsin and the Aspergillus proteinase, and one inhibitor which acted only on the Aspergillus enzyme. All of these inhibitors were different from the five Aspergillus proteinase inhibitors which are abundant in the endosperm of resting seeds. Two chymotrypsin inhibitors with weaker activity on the Aspergillus proteinase were present in rootlets and also in embryos of resting seeds. These inhibitors were different from both the endospermal inhibitors and the inhibitors present in young leaves.
Effect of Succinic Acid‐2,2‐Dimethylhydrazide on Endogenous Auxin Level in Apple Shoots
Authors: JINDAL K. K. , DALBRO SVEN
Published: April 2006

Endogenous auxin levels in the shoots of apple cv. Ingrid Marie (red mutant) treated with SADH (succinic acid‐2,2‐dimethylhydrazide) were measured. SADH was applied in aqueous solution at 12.5, 25 or 50 mM concentrations in June, 3 weeks after flowering. The defoliated shoot tips were analysed just before SADH spray and 7, 15, 30 and 60 days after spraying. Similar treatments had been made in earlier years.

When analysed before the treatment of the year started, shoot extracts of control plants contained higher auxin level than those shoots which were to receive SADH treatment, indicating a residual effect of SADH treatmens during previous years. There was almost no auxin activity in the shoots analysed after 7, 15 and 30 days of SADH treatment. The control plants maintained a high level of auxin activity during this period. However, after 60 days of treatment, shoots treated with 25 or 50 mM exhibited higher auxin activity than control shoots. There appears to be no relationship between the SADH concentration and reduction in auxin activity in the shoots at early stages after treatment.
A Replica Plating Method for Plant Cells
Authors: SCHULTE U. , ZENK M. H.
Published: April 2006

A replica plating method is described for plant cells growing in Petri dishes. The method involved a uniform application of plant cells (Morinda citrifolia L.) by spraying cells evenly on agar plates containing 60% conditioned medium. Subsequently the cells were allowed to grow through a nylon net. The net was removed from the master plate and placed upside down on replica plates. Cells from colonies adhering to the threads of the net were thus transferred to the replica plate and yielded colonies that, after a growth period of about 10–20 days, corresponded in position to the colonies on the master plate. An 80% transfer of colonies from the master plate to the copy plate was possible.
Cysteine and Methionine Regulation of Sulfate Uptake in Potato Tuber Discs (Solanum tuberosum)
Authors: MAGGIONI ANGELO , RENOSTO FRANCO
Published: April 2006

Sulfate uptake in potato tuber discs is inhibited by cysteine and methionine with an 8 h lag period. Cysteine, but not methionine, inhibition can be reversed by washing the treated discs. During the experimental period cysteine is rapidly metabolized, while methionine persists as a free amino acid. Amino acid inhibition of sulfate uptake is overcome by increasing sulfate concentration. The kinetic parameters change suggesting a loss of flexibility of the sulfate uptake system caused by sulfur amino acids.
Kinetics of Manganese Uptake by Intact Citrus Seedlings
Authors: HASSAN M. M.
Published: April 2006

Uptake of manganese by intact citrus seedlings can be represented by three phases of a single, multiphasic isotherm in the range 10−8M–2× 10−4M. The phases are separated by marked jumps and the kinetic constants increase upon transition to higher phases.
Isolation of Mitochondria from Orobanche, a “Total” Root Angiospermic Parasite
Authors: SINGH PRIKHSHAYAT , KRISHNAN P. S.
Published: April 2006

Mitochondria were isolated from the scapes of Orobanche cernua. On the basis of comparative studies with four media, a mannitol grinding medium was selected at a slightly alkaline pH and supplemented with EDTA, metabisulphite, BSA and soluble PVP. Various intermediates of the Krebs cycle, pyruvate, glutamate and NADH were oxidized by the isolated particles, though with different efficiencies. The rate of oxidation was steady for every intermediate tested over a 60 min period, except for NADH. In the majority of cases, the oxidation was accompanied by efficient coupling with phosphorylation. Antimycin A led to significant reduction in the oxygen uptake in the presence of succinate and complete suppression of phosphate‐esterification. The amount of protein recovered in the mitochondrial fraction was comparable with the reported recoveries from a number of plant tissues. The biochemical integrity of mitochondria in the particulate fraction appeared possible from: (a) the absence of respiratory response to added cytochrome c during the oxidation of succinate, (b) insignificant oxidation of exogenously added pyruvate in the absence of sparker and (c) the ability to satisfactorily couple phosphorylation to the oxidation of a number of substrates.
The Effect of Ageing on the Leghemoglobin of Cowpea Nodules
Authors: SWARAJ K. , GARG O. P.
Published: April 2006

Experiments were conducted to study the effect of ageing of the host and senescence of the nodules on the content and composition of the proteins of leghemoglobin in nodules of cowpea (Vigna sinensis L.). Total and heme protein contents of leghemoglobin were the highest in the red nodules and dwindled with the onset of nodule senescence. In the fully senescent green nodules the total proteins decreased to a very low level, while the heme proteins were almost absent. Disc electrophoretograms of leghemoglobin obtained from red and brown nodules showed nine bands out of which only four gave positive test for heme. Greening of the nodules resulted in a considerable reduction in the intensity of the bands. Senescence of the host plant resulted in a reduction in the number of leghemo‐globin proteins in all types of nodules and brought about a drastic change in their electrophoretic mobility.
Induced Embryo Formation in Anther Cultures of Several Anemone Species
Authors: JOHANSSON LARS , ERIKSSON TAGE
Published: April 2006

Embryo formation was induced in anther cultures of Anemone virginiana and some other species of the same genus. Activated charcoal was included in the culture medium which gave the higher percentage embryos. When the cytokinin 2ip was included (10−6M) embryo formation was also induced but at a lower percentage. This indicates that abscisic acid (ABA) can be involved in the normal inhibition of embryo formation in pollen.
Lipid and Fatty Acid Composition of Tree‐Growing and Terrestrial Lichens
Authors: DERTIEN BART K. , DE KOK LUIT J. , KUIPER PIETER J. C.
Published: April 2006

A comparison of lipid and fatty acid composition was made of the tree‐growing lichens Evernia prunastri (L.) Ach., Parmelia saxatilis (L.) Ach. and Hypogymnia physodes (L.) Ach. and the terrestrial species Cetraria islandica (L.) Ach. and Cladonia impexa Harm.

In the terrestrial species the total lipid content varied strongly during spring, while the tree‐growing species showed much less variation. Phospholipid and sterol content of all lichens was unusually low. Monoglycosyl diglyceride was absent from Parmelia saxatilis. Fatty acids common to higher plants as palmitic, stearic, oleic, linoleic and linolenic acid were invariably present in all lichen species. In addition large quantities of extra‐long chain fatty acids like behenic acid, eicosadienoic acid and cyclic aliphatic lichen acids were present in the terrestrial species. The degree of (poly) unsaturation decreased in the order Evernia prunastri, Parmelia saxatilis. Fatty acids common to higher plants as palmitic, stearic, impexa, which decrease was compensated by an increase in extralong chain fatty acids and lichen acids. It is suggested that the lichen acids are of adaptive value for lichen species growing in the terrestrial habitats, which were characterized by extreme diurnal temperature variations. Just as the polyunsaturated fatty acids, lichen acids guarantee at lower temperatures a high flexibility of the membranes involved, at the same time as they are less susceptible to photo‐oxidation at the high daytime temperatures.
Wavelength Dependence in the Red and Far‐Red for Induction of Phytochrome Increase in Mung Bean Hooks
Authors: TANADA T.
Published: April 2006

The wavelength dependence for a radiation induced increase of phytochrome in mung bean hooks (Vigna radiata L.), preirradiated with red light, was determined between 640 to 800 nm. Radiation between 640 to 700 nm and 780 to 800 nm had little effect on phytochrome concentration in hooks pretreated with red. Two bands of far‐red light, one at 710 nm and the other at 750 to 760 nm, were found to increase phytochrome content about four times. Besides the requirement for a photochemical process, one or more dark processes appear to be necessary for the induction of phytochrome increase.
Leaf Water Potential and the Rooting of Cuttings under Mist and Polythene
Authors: LOACH K.
Published: April 2006

The relationship between leaf water potential and rooting was investigated in cuttings of Rhododendron (Hardy Hybrid) ‘Mrs. W. Agnew’, Ceanothus thyrsiflorus Esch. and Hebe (Garden Hybrid) ‘Caledonia’ (of the ‘Mrs. Winder’ group), during propagation under mist and polythene. Water potentials well below –10 bars frequently occurred and low mean water potentials related to poor rooting. Propagation under polythene gave better results than mist in the lower radiation conditions of winter but the reverse occurred under high radiation conditions. Treatment of cuttings with a poly‐vinyl resin antitranspirant coating temporarily increased leaf water potentials in the consistently humid conditions under polythene but not under mist. The coating peeled and lost its effectiveness within 6 weeks.

Multiple regression analysis showed that much of the variation in water potential in cuttings under mist could be accounted for by inclusion of three variables, viz. current day's radiation, number of days from insertion of the cuttings and either the previous day's leaf water potential or radiation. Under polythene the influence of yesterday's water potential was relatively unimportant, probably because cuttings were able to take up water overnight from condensation on the under surface of the polythene.

For optimal rooting, propagation procedure must ensure that high leaf water potentials are maintained, but conventional methods do not always achieve this.
The Effect of Phytohormones on Chlorophyll(ide), Protochlorophyll(ide) and Carotenoid Formation in Greening Dark Grown Wheat Leaves
Authors: BENGTSON CURT , KLOCKARE BIRGITTA , LARSSON STIG , SUNDQVIST CHRISTER
Published: April 2006

The influence of phytohormones on chlorophyll and carotenoid formation during the greening of irradiated dark grown wheat leaves (Triticum aestivum L. cv. Starke II Weibull) was studied. Leaves were floated on solutions of abscisic acid, gibberellic acid and kinetin for 24 h. The chlorophyll and carotenoid contents were determined during a subsequent period of 48 h of continuous irradiation. Leaves treated with abscisic acid showed a longer lag phase and a lower rate of accumulation of chlorophyll as compared to the control than did leaves treated with gibberellic acid and kinetin. The carotenoid content was low both in leaves treated with abscisic acid and in those treated with gibberellic acid. Treatment with abscisic acid lowered the protochlorophyllide regeneration after a saturating light flash while gibberellic acid as well as kinetin had no effect. The influence of ABA was partly dependent on an increase of the wounded part of the cut leaf segments. The accumulation of protochlorophyllide in leaves treated with δ‐aminolevulinic acid was not affected by the different hormonal treatments. These results suggest that the main effect of abscisic acid is probably outside the chloroplast, i.e. on the formation or transport of δ‐aminolevulinic acid.
Flavolans and Growth‐Promoting Catechins in Young Shoot Tips of Prunus Species and Hybrids
Authors: FEUCHT W. , NACHIT M.
Published: April 2006

Young shoot tips of species and hybrids from the Prunus section eucerasus contain catechin, epicatechin and flavolans (oligomeric flavans including biflavans). Prunus avium shoot segments, 2 mm in length, were excised from the elongating zone of growing shoots and cultured in vitro on a liquid Murashige and Skoog medium containing indolyl‐3‐acetic acid and benzyl adenine. Supplementation of the same medium with (+)‐catechin and epicatechin resulted in apparent promotion of callus growth. This effect was greater under long day conditions than under continuous dark.
Determination of Fatty Acid Composition of Spore Lipids of the Moss Polytrichum commune by Glass Capillary Column Gas Chromatography
Authors: KARUNEN P.
Published: April 2006

Fatty acid methyl esters of Polytrichum commune spore triglyceride and mono‐ and diglycosyl diglyceride fractions were analysed by glass capillary column gas chromatography provided with a precolumn system. The composition of the fatty acids in the lipid fractions differed only quantitatively: the diglycosyl diglyceride fraction was characterized by a high content of C 18: 3ω3 (67.7%), and the triglyceride and monoglycosyl diglyceride fractions by about 35%. The monoglycosyl diglyceride fraction contained a high proportion of C 14: 0 (18.4%). In all fractions the content of polyunsaturated C 20 acids was low, ranging from trace amounts to 4.9%.