bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Glyphosate on Metabolism of Phenolic Compounds
Authors: HOAGLAND ROBERT E. , DUKE STEPHEN O. , ELMORE C. DENNIS
Published: April 2006

Amounts of extractable phenylalanine ammonia‐lyase (PAL; E.C. 4.3.1.5) activity increased in the axes of 3–day‐old, dark‐grown soybean seedlings [Glycine max (L.) Merr.] shortly after the seedlings were transferred to glyphosate [N‐(phosphonomethyl)‐glycine] solutions. The stimulation of PAL activity in herbicide‐treated tissue (as compared to control tissue) was detectable as early as 12 h after treatment, whereas growth inhibition (length, fresh weight and dry weight) was not significantly affected until 24 h on a fresh‐weight basis and at 48 h on a dry‐weight basis. PAL activity increased with time (12–72 h) in herbicide‐treated axes when expressed as activity per gram fresh weight, specific activity, and on a per axis basis. PAL activity stimulation correlated positively with glyphosate concentration from 10–4 to 10–3M. PAL activity in control tissues remained nearly constant over the sampling period (12–72 h). Total alcohol‐soluble hydroxyphenolic compound levels in treated axes were not significantly different from the control at any sampling period. The total soluble amino acid pool showed a general decrease with time in glyphosate‐treated tissues. The phenylalanine pool was lowered with treatment time and the ammonia concentration (per g fr. wt. basis) was increased after treatment. No significant differences were noted in the concentration of soluble protein of glyphosate‐treated tissue when compared to controls. Visual effects (stunting, lack of secondary root formation, and necrotic areas) of glyphosate were more obvious in the root than in the hypocotyl. Analysis of various chemical constituents substantiated that other glyphosate effects were more clearly demonstrable in the root than in the hypocotyl or in the intact axis. On a per root basis glyphosate markedly increased PAL activity while reducing free phenylalanine, free tyrosine, soluble hydroxyphenolics, total free amino acids and ammonia content. The effect of glyphosate in the root was greatest on phenylalanine content, reducing it five‐fold. The results indicate that glyphosate could exert its effect through either induction of PAL activity and/or inhibition of aromatic amino acid synthesis.
Nitrogen Fixation Associated with Sand Grain Root Sheaths (Rhizosheaths) of Certain Xeric Grasses
Authors: WULLSTEIN L. H. , BRUENING M. L. , BOLLEN W. B.
Published: April 2006

Nitrogen fixation (acetylene reduction) was found to be associated with sand grain root sheaths (rhizoseaths) occurring on the following xeric grasses: Oryzopsis hymenoides (Roem. and Shult.) Ricker, Agropyron dasystachyum (Hook.) Scrib., Stipa comata Trin. and Rupr., and Aristida purpurea Nutt. Acetylene reduction rates associated with whole plant specimens of these species varied from 515 to 920 nmol C2H4/(g dry wt.) × (6 days). Nitrogenase activity was shown to be associated with the rhizosheaths. Bacillus polymyxa‐like nitrogen fixers were isolated from the rhizosheaths of each grass. The isolates reduced acetylene and assimilated 15N2.
Changes in Ribonuclease Activity of Wheat Plants during Water Stress
Authors: YI CHOK WANG , TODD GLENN W.
Published: April 2006

RNases from control and water‐stressed wheat seedlings were purified by ion exchange chromatography, gel filtration and gel electrophoresis. The enzyme appeared to be identical from both treatments and only one species was found. Subcellular distribution between soluble and particulate fractions was not changed by water stress treatment. Total quantity of RNase per plant was similar in control and water‐stressed plants, although since the dry weight of treated plants was less, the activity per gram was significantly higher. Crude homogenates of leaf extracts contained an RNase inhibitor with a greater amount being present in control leaves. No evidence was found to indicate that new types of RNases are synthesized during water stress.
Osmotic Requirement for Shoot Formation in Tobacco Callus
Authors: BROWN DANIEL C. W. , LEUNG DAVID W. M. , THORPE TREVOR A.
Published: April 2006

Tobacco callus grown on medium containing 3% sucrose (w/v) shows optimum growth and produces the highest number of shoots; whereas cultures grown on medium with lower or higher sucrose levels show a reduced growth rate and capacity to form shoots. Cultures grown on a low sucrose containing medium produce a high number of shoots only if the medium is supplemented with mannitol to give the same water potential as that of the 3% sucrose medium. Mannitol cannot replace the sucrose requirement for growth. Increased levels of Bacto Agar, tricarboxylic acid cycle intermediates and amino acids added to the medium do not promote shoot formation or replace the carbohydrate requirement for that process. The success in partially replacing the sucrose requirement for shoot formation with mannitol supports the view that part of the tissue carbohydrate is acting in an osmoregulatory role. This finding is further interpreted in terms of the hypothesis of turgor‐driven growth and cell expansion.
Seasonal and Experimentally Induced Changes in the Ultrastructure of Chloroplasts of Pinus silvestris
Authors: MARTIN BJÖRN , ÖQUIST GUNNAR
Published: April 2006

The ultrastructure of chloroplasts in mesophyll cells of Pinus silvesris was examined under the electron microscope. Secondary needles were regularly sampled from a tree in a natural stand for one year. Primary needles from one‐year‐old seedlings exposed to frost hardening and dehardening conditions in a controlled environment chamber were also studied. These seedlings were exposed to 8 or 55 W m‐2. All needles were put in fixative at the different sampling dates and stored in a refrigerator until they were prepared for electron microscopy at the end of the experimental period.

During the summer the choroplasts were symmetrically shaped and heavily loaded with starch. The membrane systems were well developed and consisted of both grana and stroma thylakoids. In autumn and during early artificial frost hardening the starch content was reduced, the chloroplasts appeared amoeboid and membrane‐free stroma regions were seen. Later the chloroplasts became swollen and aggregated in one part of the cell. Starch was lost and the chloroplasts aggregated earlier at 8 W m‐2 than at 55 W m‐2. During winter the stroma thylakoids were first reduced in number and later even the grana thylakoids were damaged, resulting in mostly disorganized single membranes. Also the chloroplast envelope disappeared. In spring and early summer the chloroplasts migrated to the proximity of the cell walls. The membrane systems were reorganized and starch accumulated. During the first days of artificial dehardening the photosynthetic membranes were severely damaged, especially at 55 W m‐2, but soon new membranes were formed. Starch accumulated earlier at 55 than at 8 W m‐2.

The reported ultrastructural variations are discussed in relation to functional and biochemical fluctuations caused by the season or by artificial variations in the climate as demonstrated earlier.
The Effect of Benzyladenine on Changes in Nuclease and Protease Activities in Intact Bean Leaves during Ageing
Authors: NAITO KUNIHIKO , IIDA AKIRA , SUZUKI HIROSHI , TSUJI HIDEO
Published: April 2006

Primary leaves of intact bean plants (Phaseolus vulgaris L.) were treated with benzyladenine (BA) at different stages during growth. Changes in DNase, RNase, and proteas activities in the leaves were followed. Unlike the case of various excised tissues, cytokinin raised the activities of these hydrolases in intact bean leaves. Because BA elevated the levels of DNA, RNA, and protein in intact leaves, it may stimulate both synthesis and decomposition of these cellular constituents. The hydrolase activities showed differential responses to BA according to the age at which the leaf received the hormone treatment.
Effects of Oxygen Concentration on the Respiration of Excised Root‐Tip Segments of Maize and Rice, and of Germinating Grains of Rice and Buckwheat
Authors: GIRTON RAYMOND E.
Published: April 2006

In view of the known tolerance of rice (Oryza sativa) to wet soils, in contrast to maize (Zea mays), a comparison of the respiratory responses of the two plants to different O2 concen trations was made. It was found that if the O2 concentration was raised to 100%, an increase was observed of the O2 input and the CO2 output in maize root‐tip segments and in germinating grains of rice and also in buckwheat (Fagopyrum sp.). In marked contrast rice root‐tip segments, when treated with 100% O2, exhibited no such increase over the air controls. Increased O2 concentrations decreased RQ values ranging from 2.0 (with 5% O2) to 0.86 (with 100% O2). Air‐control RQ values were lowest with maize roots (0.9) and highest with germinating rice grains (1.0). Rice grains also exhibited the highest F/R ratio (0.85), and buckwheat grains the lowest (0.45). The addition of sucrose to maize root tips tended to promote fermentation (CO2 output) rather than aerobic respiration (O2 input).
Acides aminés libres et protéiques des divers types de rameaux du Periploca graeca: Rôle dans la circumnutation des tiges volubiles et compartimentation intracellulaire
Authors: MELIN D. , VALLEE J. C. , VANSUYT G. , PREVOST J.
Published: April 2006

Free and Bound Amino Acids in the Different Shoot Types of Periploca graeca: Role in the Circumnutation of Twining Shoots, and Cellular Compartmentation.

A study has been made of amino acids of wall proteins, cytoplasmic TCA insoluble proteins and proteins of organelles in growing tissues from three types of shoots: short upright, twining, and creeping, all carried by the same specimen of Periploca graeca L. Each shoot type presents a specific pattern. The twining shoots are very rich in cytoplasmic TCA‐insoluble proteins. The upright shoots distinguish themselves by a high level of proteins in the organelles and in the cell‐wall. However, the composition of wallproteins is almost the same in the three types of shoots. This result excludes the existence of particular wall proteins (extensin, for example) in the twining and rapidly growing shoots. In these shoots the high level of free prolin is not a consequence of low incorporation in the proteins. Distribution of prolin, aspartic acid and glutamic acid between the cellular compartments (wall, hyaloplasm and organelles) has a specific pattern in each shoot type.
Nitrate Uptake by Manganese‐Deficient Lemon Plants
Authors: LERER MICHAEL , BAR‐AKIVA AVIGDOR
Published: April 2006

The uptake of nitrate and water was followed in Eureka lemon (Citrus limon (L.) Burm. f.) plants grown in solution culture in a greenhouse under short (3–6 months) and long‐term (22–24 months) Mn‐nutrition stress. Uptake was determined from depletion in the nutrient solution.

Under short‐term stress, manganese‐deficient plants absorbed 14.5% more nitrate and 3.4% more water than the control plants, on a weight basis. Under long‐term stress there was a three‐fold increase in nitrate and a two‐fold increase in water uptake in the Mn‐deficient plants.

The intensive nitrate uptake under Mn‐deficiency stress was more spectacularly demonstrated in plants which were exposed also to low nitrogen supply. The low‐nitrogen Mn‐deficient plants absorbed more nitrate, had less stunted growth and developed fewer visible symptoms of both N and Mn deficiencies than high‐nitrogen Mn‐deficient plants.
Nitrate Uptake Effectiveness and Utilization Efficiency of Two Plum Clones
Authors: THERIOS IOANNIS N. , WEINBAUM STEVEN A. , CARLSON ROBERT M.
Published: April 2006

Nitrate uptake and utilization efficiencies of two plum clones, Marianna 2624 (Prunus cerasifera×Prunus munsoniana?) and Myrobalan 3‐J (Prunus cerasifera) in stirred solution cultures were investigated. Myrobalan 3‐J had a significantly lower NO3‐ compensation point (i.e., greater capacity for nitrate depletion) but ceased growth earlier than Marianna 2624 under severe N stress. The maximum velocity of NO3‐ uptake was 33% higher in Marianna 2624 than Myrobalan 3‐J. The nitrogen efficiency ratio (i.e., mg dry weight produced/mg nitrogen absorbed) of Marianna 2624 was 40% higher than Myrobalan 3‐J when nitrogen was severely limiting (28 mg nitrogen per plant). Thus, Marianna 2624 plants may be capable of growth at lower mean nitrogen concentrations.
The Effect of Potassium Deficiency on Stomatal and Cuticular Resistance in Tea (Camellia sinensis)
Authors: NAGARAJAH S.
Published: April 2006

The effect of potassium deficiency on cuticular resistance and diurnal variation in stomatal diffusive resistance was studied in tea (Camellia sinensis). The plants were grown in sand and potassium deficiency induced by withholding the supply of potassium.

The results showed that during the day potassium‐deficient leaves had a higher stomatal diffusive resistance than control leaves. However when solar radiation was reduced by clouds the stomatal diffusive resistance in both control and potassium‐deficient leaves was not significantly different. Night opening of stomata was observed in both control and potassium‐deficient leaves, but noticeably lower in the latter. Potassium‐deficient leaves had a lower cuticular resistance than control leaves.
The Effect of Salinity on Growth, Cation Content, Na+‐Uptake and Translocation in Salt‐Sensitive and Salt‐Tolerant Plantago Species
Authors: ERDEI LÁSZLÓ , KUIPER PIETER J. C.
Published: April 2006

Growth of salt‐sensitive Plantago media L. and salt‐tolerant P. coronopus L. and P. maritima L. was followed under saline conditions. Growth was reduced according to the ecological features of these species: P. media was sensitive to 25 mM NaCl, while P, coronopus and P. maritima could grow in 150 mM and 300 mM NaCl, respectively. The three Plantago species accumulated Na+ in the shoot and maintained a relatively low Na+ level in the root. K+. Mg2+ and Ca2+ levels of both shoots and roots decreased with increasing salinity. The results suggest that the difference between salt‐resistant and salt‐sensitive species is located in the ion secretory system which is involved in the ion translocation from the root to the shoot rather than in the primary uptake process through the plasmalemma of the cortical cells.
Germination, Utilization of Storage Materials and Potential for Cyanide Release in Cultivated and Wild Sorghum
Authors: MARBACH IRITH , MAYER A. M.
Published: April 2006

Sorghum halepense germinates only after storage and its germination is impeded by its glumes. On germination its metabolism is more rapid than is S. bicolor, as indicated by loss of dry weight, starch and protein and formation of soluble protein and soluble sugars. Fresh weight formation is also more rapid in S. halepense. A method for determining the potential for cyanide liberation is described. S. halepense builds up the potential rapidly and apparently maintains it after germination. This process is also slower in S. bicolor. The results show that the cultivated species is slower in all the processes leading to germination than the wild one.
The Influence of Light and Temperature on Isoprene Emission Rates from Live Oak
Authors: TINGEY DAVID T. , MANNING MARYBETH , GROTHAUS LOUIS C. , BURNS WALTER F.
Published: April 2006

There is a growing awareness of the role of vegetation as a source of reactive hydrocarbons that may serve as photochemical oxidant precursors. A study was designed to assess independently the influence of variable light and temperature on isoprene emissions from live oak (Quercus virginiana Mill.). Plants were conditioned in a growth chamber and then transferred to an environmentally controlled gas‐exchange chamber. Samples of the chamber atmosphere were collected; isoprene was concentrated cryogenically and measured by gas chromatography. A logistic function was used to model isoprene emission rates. Under regimes of low temperature (20°C) or darkness, isoprene emissions were lowest. With increasing temperature or light intensity, the rate of isoprene emission increased, reaching maxima at 800 μE m‐2 s‐1 and 40–44°C, respectively. Higher temperatures caused a large decrease in emissions. Since the emissions of isoprene were light‐saturated at moderate intensities, temperature appeared to be the main factor controlling emissions during most of the day. Carbon lost through isoprene emissions accounted for 0.1 to 2% of the carbon fixed during photosynthesis depending on light intensity and temperature.
Structure of Protochlorophyll‐containing Plastids in the Inner Seed Coat of Pumpkin Seeds (Cucurbita pepo)
Authors: SUNDQVIST CHRISTER , RYBERG HANS
Published: April 2006

The inner seed coat of seeds of Cucurbita pepo L. cv. Ohlsens Enke Köks was used to study the development of protochlorophyll‐containing plastids with an abnormal ultrastructural composition. The pumpkins were harvested at different stages during fruit development and they thus contained seeds with different developmental stages. The dry weight of seeds of the developmental stages used varied from 0.04 g to 0.3 g. Such a series of seeds with decreasing water content indicating increasing maturity contained different amounts of protochlorophyll, from 0.20 μg/g fresh weight to 500 μg/g fresh weight. The ultrastructure of the protochlorophyll containing plastids changed greatly during development. In young seeds with a low content of protochlorophyll, regular prolamellar bodies were found and starch grains filled most of the plastids. During development the starch content decreased and the prolamellar bodies increased in size and lost their regularity. During maturation the plastids accumulated plastoglobuli, probably containing protochlorophyll, and finally the internal structure of the prolamellar body tubular complex was lost.
Cadmium Influence on Respiratory Gas Exchange of Pinus resinosa Pollen
Authors: STRICKLAND RICHARD C. , CHANEY WILLIAM R.
Published: April 2006

Release of CO2 and uptake of O2 by Pinus resinosa Ait. pollen treated with 0, 0.004, 0.045, or 0.450 mM Cd2+ were determined manometrically. Respiration after 1.5 h was stimulated in the 0.450 mM treatment, but declined sharply after 3.5 h. CO2 evolution was inhibited more than O2 uptake. Pretreatment with Cd2+ inhibited aflization of exogenous sucrose, and conversely, exogenous sucrose did not overcome Cd2+ effects on gas exchange. Cd2+ did not act as a classical uncoupler of oxidative phosphorylation. There was no correlation of pollen germination and germ tube elongation with Cd2+ effects on gas exchange.
Phospholipid Involvement in Frost Tolerance
Authors: SIKORSKA ELŻBIETA , KACPERSKA‐PALACZ ALINA
Published: April 2006

Changes in frost tolerance and in phospholipid content were studied in the leaves of winter rape plants (Brassica napus L. var. oleifera L. cv. Górczański) grown under natural or artificially controlled conditions. Frost hardening was found to be a three‐stage process. During the first stage, occurring at low but above freezing environmental temperatures, phospholipid changes do not seem to be directly related to the leaf frost tolerance. This stage of hardening is possibly related to a metabolic shift caused by the cessation of growth. The achievement of the second level of frost tolerance in the fully turgid leaves depends on the occurrence of sub‐freezing temperature and is related to increase in phospholipid level. It was shown that freezing brought about phospholipid degradation which was reversible only in slightly injured leaves with a relatively high phospholipid content. The third stage of hardening is related to frost‐induced dehydration of the cells and may overlap the second one.
Oscillations of Leaves of Abutilon theophrasti (Velvetleaf) and their Sensitivity to Bentazon in Relation to Low and High Humidity
Authors: KOUKKARI WILLARD L. , JOHNSON MARGO A.
Published: April 2006

The upper leaf surfaces of velvetleaf (Abutilon theophrasti Medic.) contain trichomes which facilitate the adhesion of droplets of solution, even when the leaves are oriented in a vertical (night) position. Leaves of plants subjected to conditions of high relative humidity were more injured by bentazon (3‐isopropyl‐1H‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide) than leaves under low soil moisture and relative humidity. Although a significant 24‐h oscillation in the sensitivity of leaves to bentazon was sometimes evident under both high and low humidity conditions, it was definitely more evident in the latter. Generally, the second leaves of plants in the three leaf stage were more consistent for displaying oscillations in sensitivity than the first. The youngest leaves were the most sensitive to bentazon but generally did not display pronounced daily oscillations. The abscission of cotyledons appeared to have possible merit as a bioassay for monitoring leaf injury.
The Influence of Light Quality on Levels of Ahscisic Acid in Tomato Plants, and Evidence for a Novel Abscisic Acid Metabolite
Authors: LOVEYS B. R.
Published: April 2006

Tomato plants were grown in growth cabinets under two different light sources. One source consisted of white and red fluorescent tubes (Red cabinet), while the second consisted of both tungsten filament and fluorescent lamps (Far red cabinet). Energy fluence rates were adjusted to give equal photosynthetic rates in the two cabinets. Extension growth was approximately three times greater in the Far‐red cabinet. No difference could be detected in abscisic acid (ABA) levels in leaves or petioles of plants grown under the two light regimes, but levels were 40–90% greater in stems of the slower growing plants illuminated with fluorescent light only.

Exogenously applied ABA effectively reduced the growth rate of the plants in the Far‐red cabinet to that of plants in the Red cabinet. However, it was shown that light‐induced changes in growth rates occurred before any change in endogenous ABA could be demonstrated, thus precluding a role for ABA in the initial response to a change in light quality.

The changed ABA levels appeared to be the result of a modified pathway of ABA degradation. Evidence is presented for a novel metabolite of ABA which yields free ABA on basic hydrolysis.
Cultivar Differences in Starch Content and Protoplast Yields from Root Cortical Ex plants of Pisum salivum
Authors: JEAN CROWDER ANTOINETTE , LANDGREN CRAIG R. , ROCKWOOD LARRY L.
Published: April 2006

Protoplasts were isolated from root cortical explants of thirteen cultivars of Pisum sativum. The roots were tested for starch in the cortical tissues. There was a considerable range in the average protoplast yields and the coefficient of variation of those yields from the thirteen cultivars. Cultivars with a higher incidence of starchy roots had lower average explam protoplast yields and greater variation in their protoplast yields. Significantly higher protoplast yields were observed from explants with no starch or few starchy cells. Increasing the germination time of the peas increased the starch content in the seedling roots and decreased the protoplast yields.
Differences in Cuticular Resistance in Relation to Transpiration in Tea (Camellia sinensis)
Authors: NAGARAJAH S.
Published: April 2006

Experiments were carried out to investigate whether there were clonal differences in cuticuiar resistance to transpiration in tea (Camellia sinesis) leaves. The cuticular resistance of’ sun and shade leaves was also compared. The drying rate of detached leaves was measured and used as an estimate of cuticular resistance to transpiration. The results showed that there were clonal differences in cuticular resistance in mature and old leaves but not in young leaves. In clonal tea there appeared to be an inverse relationship between she rate of leaf growth and the cuticular resistance in mature leaves. Shade leaves had a higher cuticular resistance than sun leaves.
Fatty Acid Levels in Apple Leaves of Different Age as Affected by Temperature
Authors: KETCHl D. O. , KUIPER P. J. C.
Published: April 2006

Relative electrical conductivity (RC) values and Tally acid levels were measured on apple leaves of different ages exposed to 0 and 20°C. RC values were measured at—3°C and high RC values indicate frost‐sensitive tissue. A prolonged period at 0°C gave an increased RC value of the leaves, which indicates damage. At 20°C the RC values were lower in older leaves than in young leaves.

The fatty acids level as well as the degree of saturation were different at different ages of the leaves. Young leaves showed a higher fatty acid level in plants held at 20°C than in plants at 0°C. The older leaves maintained the same level after 12 days at 20°C as after 3 days at 20°C. The fatty acid level decreased at 0°C. The linolenic acid level followed the same trend as total fatty acids, indicating that synthesis and degradation of linolenic acid can occur in the same plant depending on the age of the leaf and on the temperature. Cold resistance and linolenic acid levels were correlated in both old and young leaves at 20°C and in older leaves at 0°C. There was no correlation between cold resistance and levels of linotenic acid levels in young leaves at 0°C. Two hiosynthetic pathways for linolenic acid synthesis are discussed.
Diurnal and Seasonal Changes in Leaf Water Potential Components and Elastic Properties in Response to Water Stress in Apple Trees
Authors: DAVIES FREDERICK S. , LAKSO ALAN N.
Published: April 2006

Apple trees are very drought tolerant, having the capability to grow and carry on photosynthesis even at low water potentials. Much of the tolerance is due to the ability of apple leaves to maintain turgor potentials at levels conducive to growth and stomatal opening. Diurnally, leaf turgor is maintained through decreases in osmotic potentials (due to active solute accumulation), osmotic adjustment, or to concentration of solutes via tissue water loss. These two processes combined may decrease osmotic potentials by as much as 1.65 MPn during the day. Seasonally, osmotic potentials remain fairly constant, but leaf elasticity increases, allowing growth to continue and stomata to remain open us water and turgor potentials become progressively lower. Release of stored water from plant tissues to the transpiration stream is another means of preventing water potentials from reaching critical values for stomatal closure. A combination of a number of these physiological adaptations may account for much of the drought tolerance in apple trees.
Carotenoid and Steroid Syntheses by Carrot Cells in Suspension Culture
Authors: SHIMIZU KAYOKO , KIKUCHI TOHRU , SUGANO NOBUHIKO , NISHI ARASUKE
Published: April 2006

Biosynthesis of carotenoids and steroids in tissue cultures of carrot cells I Daucus carota L.) was studied by measuring the change in their contents and incorporation of 14lC‐acelate. The rate of synthesis of these plant products varied significantly during the growth cycle in batch culture. Carotenoids were most actively synthesized in the early logarithmic phase and the synthetic rate sharply declined as the culture aged, whereas the rate of accumulation of phytosterols was highest at the end of the growth phase. Newly synthesized carotenes were shown to undergo turnover during the growth. The synthesis of both carotecnoid and steroid was stimulated by 2.‐ 4‐dichlorophenoxyacetic acid.
Quantitative and Qualitative Changes in Peroxidase during Germination of Mung Bean under Salt Stress
Authors: SHEORAN I. S. , GARG O. P.
Published: April 2006

Seeds of mung bean (Phaseolus aureus Roxb.) cv. Pusa Baisakhi were surface sterilized with sodium hypochlorite solution and sown both in Petri dishes and in sand culture containing aqueous solutions of four different salts, viz. NaCI, KCI, Na2SO4 and K2SO4, each at 5 and 10 S/cm. Peroxidase activity and its isoenzymes were studied in different plant parts at suitable time intervals during germination. Activity of peroxidase increased in embryo axis and leaves but decreased in cotyledons and roots with different salt treatments to varying degrees. A highly significant inverse correlation (r= ‐0.931 was found between the peroxidase level and the growth of embryo axis under saline conditions. The number of isoenzymes of peroxidase increased with increase in the time of germination. Salinity treatments resulted in the appearance of new isoenzymes in all the plant organs except roots where the isoenzymic pattern remained unchanged. Different types of salinity resulted in the appearance or/and disappearance of different isoenzymes.
Stomatal Responses of Fraxinus pennsylvanica Seedlings during and after Flooding
Authors: KOZLOWSKI T. T. , PALLARDY S. G.
Published: April 2006

Effects of flooding for 10, 20, 30, or 40 days on leaf diffusion resistance (r1) of fraxinus pennsylvanica seedlings were studied during the period of flooding and continuing for 17 days after flooding. All Flooding treatments induced stomatal closure, as indicated by increased r1. There was some evidence of stomatal adaptation to flooding, with stomata beginning to reopen after a critical period of flooding. After termination of flooding, stomata opened further within 6 to 10 days to near preflooding levels. The degree of stomatal opening was only slightly higher after 10 days than after 40 days of flooding. Some stomata may have been permanently damaged by flooding. The stomatal adaptation to flooding as well as rapid recovery of stomatal opening, even after prolonged flooding, appeared to be important factors in the flooding tolerance of Fraxinus petmsylvanica and are consistent with its distribution on wet sites.
The Effect of 2,3.5 Triiodobenzoic Acid on Caulogenesis in Callus Cultures of Tomato and Pelargonium
Authors: CASSELLS ALAN C.
Published: April 2006

Stem explants from winter grown tomatoes cultured on a cytokinin, auxin‐free medium, developed one or two adventitious shoots at the top end of the explant. Addition of the auxin transport inhibitor. 2,3,5‐triiodobenzoic acid (TIBA) to the medium stimulated caulogenesis with loss of polarity.

Callus, initiation in pelargonium and ‘geranium’ petiole explants requires both auxin and cytokinin. On transfer, after callus induction to an auxin‐free medium, rhizogenesis occurs in pelargonium cultures followed by caulogenesis. Few shoots develop and unless these are removed, further caulogenesis is suppressed. Bud‐like structures were formed in the callus. Subculture on auxin‐free medium containing cytokinin and TIBA resulted in shoot formation from these bud‐like organs. An analogy with apical dominance is suggested. In ‘geranium’ callus, shoots developed with a low frequency (c. in 2% of the cultures): caulogenesis was increased to 80% when calli were subcultured from auxin‐free, cytokinin medium after green nodule formation to cytokinin‐TIBA medium.

Histological studies of green nodules in ‘geranium’ callus indicated a variation in morphological development within and between nodules. It is suggested that auxin synthesis may occur at some microscopic stage in morphogenesis in ‘geranium’ cultures which suppresses further caulogenesis. This may be overcome by the addition of TIBA to the medium at the appropriate stage in morphogenesis.

The possible interaction of endogenous auxin in morphogenesis is discussed.
Light and Temperature Requirements during Fruit‐Body Development of a Basidiomycete Mushroom, Coprinus congregates
Authors: ROBERT J. C. , DURAND R.
Published: April 2006

Light initiated fruit body primordia of Coprinus congregatus Bull, ex Fr. grown at relatively high temperature (25°C) require a single dark period or low‐temperature induction for completion of fruit‐body development. The dark period requirement varied with the temperature regime during the inductive dark period A minimum requirement of 2.5 h was found al 15–20°C. Darkness always promotes development of fruit‐body primordial, but cannot, be regarded as an absolute necessity until temperature exceeds about 17.5°C. Normal development of me primordia without darkness was obtained by lowering the temperature to 10°C for 6 h. It appeared that at high temperatures two successive stimuli were required for basidiocarp maturation, a light‐off and a subsequent signal light‐on signal. On the contrary, at 10°C a single low‐temperature signal seemed to be involved. Thus, induction of fruit‐body development could be produced by alternative pathways. These developmental features have been extended to other fungi and compared with the flowering processes of some short‐day plants.
Differentiation in Lilium Bulbscales Grown in vitro. Effect of Various Cultural Conditions
Authors: TAKAYAMA SHINSAKU , MISAWA MASANARU
Published: April 2006

Tissue cultures of Lilium auratum Lindl. and L. speciosum Thunb., which were derived from bulbscales, all appeared to differentiate organs. The effect of cultural conditions on the differentiation of bulblets and roots was examined.

The best material for bulblet formation was bulbscales of intact or in vitro produced bulblets. The optimum temperature was 20°C and optimum pH was 6. Effect of irradiance on organ formation was not obvious but leaf emergence was stimulated.

Higher kinetin concentrations stimulate the formation of numerous bulbscalcs. High NAA concentrations induce roots. On the other hand kinetin inhibits the NAA effect on root formation. A high sucrose concentration stimulated organ formation, but the number of bulblets was at a constant level in the medium containing between 10 and 90 g/l of sucrose. The formation of bulblets and their growth were stimulated at increasing strength of Murashige‐Skoog's (MS) medium, but the length of roots was inhibited. Inter action of strength of MS medium and sucrose concentration was examined. High concentration of both components stimulated bulb lei growth, but the second strength of MS medium containing 90 or 120 g/l sucrose stimulated callus induction and inhibited the growth of bulblets.

Maximum growth took 100 days for bulblets and about 50 days for roots. The change of fresh weight/dry weight ratio during differentiation is also discussed.
Effect of Far Red and Red Light on a Pelletable Peroxidase Activity in Extracts from Spinach Leaves
Authors: PENEL CLAUDE , GREPPIN HUBERT
Published: April 2006

The effect of in vitro irradiations on ihe pelletability of peroxitlase activity was tested in extracts prepared from leaves of light‐grown spinach (Spinacia oleracea). It appeared that far red light increased the pelletable activity and that red light reversed this effect. This phytochrome‐mediated effect occurred in a particulate fraction which banded at 39% (w/w) sucrose on an isopycnic density gradient.
Influence of ethanol on alternative oxidase in mitochondria from callus‐forming potato tuber discs
Authors: VAN DER PLAS LINUS H. W. , WAGNER MARIJKE J.
Published: April 2006

Ethanol, when added to the incubation medium of callus‐forming potato tuber discs, inhibits callus growth and causes an increase of the mitochondrial antimycin‐A resistant respiration, expressed as a percentage of state III‐respiration. This increase in resistance to antimycin‐A is the result of a poor development of the cytochrome pathway in tissue discs treated with ethanol. The development of the antimycin‐A resistant alternative oxidase sensitive to chelator is about the same for treated and untreated discs.

The respiratory control (RC) ratio of the mitochondrial respiration increases after addition of a chelator, which inhibits the alternative pathway. The RC ratio of the uninhibited mitochondrial respiration appears to be inversely related to the capacity of the alternative pathway, when mitochondrial preparations with different capacities to transfer electrons via the alternative path are compared. From the experimentally observed relation between RC‐ratio and alternative oxidase capacity, it was concluded that at least half of the capacity of the alternative path is used in uninhibited state IV respiration.
Auxin biosynthesis and metabolism in isolated roots of Zea mays
Authors: FELDMAN LEWIS J.
Published: April 2006

The synthesis and metabolism of indole‐3‐acetic acid (IAA) was investigated in isolated roots of corn, Zea mays L. Roots were cultured aseptically in media supplemented with either 14C‐tryptophan or 14C‐IAA. Exogenously supplied IAA is rapidly and completely metabolized by root tissues. The main site in the root for the synthesis of IAA is in the apex. Removal of either the root cap or the quiescent center, or the root cap and the quiescent center from the apex has no effect on the IAA‐synthesizing ability of the apex. Subdividing the terminal 2.1 cm of the root into various segments and culturing them separately stimulates IAA synthesis in these isolated root tissues. Roots in culture maintain relatively constant IAA levels, reflecting the precise controls of the level of this hormone.
The effect of adenine nucleotides and inhibitors of ADP translocation on uncoupled electron flux in bean mitochondria
Authors: LIMA M. SILVA , DE MELO D. FERNANDES
Published: April 2006

The uncoupled electron flux and the influence of adenine nucleotides on this flux in mitochondria isolated from hypocotyls of Vigna sinensis (L.) Savi cv. Seridó were examined. In order to avoid the functioning of other enzymes capable of utilizing adenine nucleotides the reaction medium was free of Mg2+. When an oxidizable NADH ‐linked substrate such as L‐malate was used, a stimulatory of adenosine‐5′‐monophosphate (AMP) and adenosine‐5′‐diphosphate (ADP) on uncoupled respiration was manifested. The stimulatory effect of AMP and ADP could not be shown when succinate was the substrate. Atractyloside and carboxyatractyloside had no effect on the stimulatory role played respectively by AMP and ADP in the presence of carbonyl cyanide p‐trifluoromethoxy‐phenylhydrazone (FCCP).
Factors affecting shoot initiation from tuber discs of potato (Solanum tuberosum)
Authors: JARRET ROBERT L. , HASEGAWA PAUL M. , ERICKSON HOMER T.
Published: April 2006

Discs of cortical and perimedullary tissue from tubers of potato (Solanum tuberosum L. cv. Superior) formed adventitious shoots when cultured on a medium containing Murashige and Skoog's salts, myo‐inositol, 100 mg/l; folic acid, 0.5 mg/l; D‐biotin, 0.05 mg/l; gibberellic acid (GA3), 0.5 mg/l; thiamine ˙ HCl, 0.1 mg/l; glycine, 2.0 mg/l; pyridoxine ˙ HCl, 0.5 mg/l; nicotinic acid, 0.5 mg/l; sucrose, 25 g/l; casein hydrolysate, 1 g/l; Bacto agar, 9.0 g/l; and a cytokinin [N6‐benzylaminopurine (BAP), N6‐γ,γ‐dimethylallylaminopurine (2iP), or N6‐furfurylaminopurine (kinetin)]. Discs of pith tissue either failed to survive or produced callus but did not undergo morphogenesis. Cytokinin was essential for explant survival, while BAP at 3.0 mg/l was most efficacious in promoting shoot initiation. Auxin was not essential for shoot initiation or development; however, a low concentration (0.03 mg/l) of α‐naphthaleneacetic acid (NAA) stimulated both explant survival and the number of shoots produced per disc. Indole‐3‐butyric acid (IBA) and indole‐3‐acetic acid (IAA) did not stimulate shoot initiation. GA3 was essential for both shoot initiation and subsequent shoot development. The highest incidence of morphogenesis (over 100 shoots in 12 weeks) occurred from tuber discs cultured at 18°C constant and under a photon flux density of 60 μE m‐2s‐1. No difference in regenerative ability was found in explants taken from source tubers stored for 0 to 20 weeks at 4°C. A histological examination indicated that shoots developed from small clusters of meristematic cells which were initiated from within small protuberances on the surface of the tuber disc 3 weeks after transfer.
The relevance of seed membrane lipids to imbibitional chilling effects
Authors: PRIESTLEY DAVID A. , LEOPOLD A. CARL
Published: April 2006

Imbibitional chilling injury during rehydration of seeds is particularly marked in soybean but not in pea. Following the previous reports that the deleterious effects of chilling on soybean germination are probably mediated at least in part through a loss of membrane integrity, differences in composition of membrane lipid components extracted from pea (chilling‐insensitive) and soybean (chilling‐sensitive) were examined. Comparative compositional analysis of phospholipids, fatty acids and free sterols revealed few disparities between the two species. When the membrane lipids were re‐formed into liposomes, little difference in permeability was found with respect to KCl, glucose or glycerol, even at chilling temperatures. It is suggested that the difference in chilling sensitivity between pea and soybean is not related to compositional differences in the major lipid components of the seed membranes.
Lipid composition and molecular organization in plasma membrane‐enriched fractions from senescing cotyledons
Authors: LEES G. L. , THOMPSON J. E.
Published: April 2006

Plasma membrane fractions isolated from cotyledons of Phaseolus vulgaris L. cv. Kinghorn at various stages of senescence showed no significant change in fatty acid saturation with advancing senescence. However, the steroliphospholipid ratio increased by about 400% as senescence intensified. The lipid phase transition temperature of the membranes, which was measured by wide‐angle x‐ray diffraction, also rose from a point well below the growing temperature for young tissue to about 50°C for membrane from extensively senescent 9‐day‐old tissue. This means that by day 4 of germination there was a mixture of liquid‐crystalline and gel phase phospholipid in the membrane matrices. Crystallinity attributable to sterol‐sterol interaction was also apparent in the diffraction patterns for senescent membranes. The co‐existence of gel and liquid‐crystalline phase phospholipid in the aging membranes as well as the crystalline sterol aggregates presumably render the storage cells of cotyledons leaky and may thus facilitate the translocation of hydrolyzed food reserves into the vascular network.
Multiphasic accumulation of nutrients by plants
Authors: NISSEN PER , FAGERIA NAND K. , RAYAR ANTONI J. , HASSAN MOKHTAR M. , HAI TANG VAN
Published: April 2006

Seedlings of rice (Oryza sativa), soybean (Glycine max) and sour orange (Citrus aurantium) were grown for 20 to 125 days under controlled conditions in nutrient solutions wiht up to 16 different concentrations of NH4+, H2PO4‐, K+, Ca2+, Mg2+ or Zn2+. Nutrient concentrations differed by up to 4 orders of magnitude (H2PO4‐ and Zn2+) and were kept constant or within certain limits by changing solutions daily. Dry weights and concentrations of N, P, K, Ca, Mg or Zn were determined for roots and tops (or roots, stems and leaves). The relationship between tissue concentration of an element and external concentration of the corresponding nutient ion was invariably multiphasic, with phases separated by sharp breaks or jumps. The kinetics of accumulation were similar to those of short‐term uptake of the same ions. Reanalysis of previously published data (including data for Mn2+) for other plants yielded, similarly, bi‐ or multiphasic isotherms for accumulation. Accumulation patterns and growth were in several instances correlated, with separate phases coinciding with regions of poverty adjustment, luxury consumption and toxicity.

Implications of multiphasic kinetics of long‐term nutrient accumulation for membrane properties, fluxes and regulation include: (i) Membranes and uptake mechanisms must remain relatively constant throughout the life of the plant with respect to affinities for ions and concentrations at which transitions occur. (ii) Rate‐limitation occurs at the plasmalemma of the root cortical cells. (iii) Uptake is at all times under multiphasic control by the external solution.
Metabolism of free sugars in relation to starch synthesis in the developing Sorghum vulgare grain
Authors: BHATIA I. S. , GUMBER S. C. , SINGH RANGIL
Published: April 2006

Accumulation of starch at expense of its free‐sugar precursors was studied in the developing grains of the ‘SL‐44’variety of Sorghum vulgare Pers. The content of starch gradually increased with the maturation of the grain and this increase was relatively fast until 18 days after anthesis. The daily rate of starch accumulation was at a maximum 15 days after anthesis. The content of total free sugars, reducing sugars, non‐reducing sugars other than sucrose, total and non‐sucrosyl fructose, and glucose also increased, reaching maximum values at 18 days after anthesis. Sucrose content gradually increased with a concomitant decrease in the activity of invertase, and sucrose was the major non‐reducing sugar in the matured grains. Detached heads incubated in labelled sugars indicated that, compared to sucrose and fructose. 14C was more efficiently incorporated from glucose into grain starch, which was maximally synthesized at the mid‐milky stage of grain development. Exogenous supply of NAD+ plus ATP stimulated the in vivo incorporation of 14C from sucrose to starch. The decline in the rate of starch accumulation did not synchronise with that of protein synthesis.
Properties of glutamate dehydrogenase from Beta vulgaris
Authors: NESSELHUT TH. , HARNISCHFEGER G.
Published: April 2006

Glutamate‐NAD oxidoreductase, E.C. 1.4.1.3 (GDH), from seedlings of Beta vulgaris cv. Rota, Jahnsch Peragis Comp., was enzymatically characterized. This enzyme with molecular weight of 2.6 × 105 has a pH optimum of around 8 for animation of α‐KGA and around 9.5 for the desamination of glutamate. The apparent Km for α‐KGA is 6.7 × 10−4M, for NH3 2.5 × 10−3M, for NADH 3.2 × 10−5M and for NAADPH 5.5 × 10−4M. NAD1 inhibits the reaction non‐competitively when NADPH serves as substrate. The apparent K1 is 4.5 × 10−4M. The data are discussed on relation to the properties of GDH from other plant sources.
Extracellular invertase from Aspergillus flavus
Authors: OLUTIOLA P. O. , COLE O. O.
Published: April 2006

An extracellular invertase was induced in cultures of Aspergillus flavus Link during growth in liquid medium that contained sucrose as the sole carbon source. Synthesis of this enzyme was repressed by the addition of glucose or fructose to sucrose‐metabolizing cells, and was induced in a glucose or fructose‐metabolizing culture by the addition of sucrose. A. flavus invertase had a pH optimum of 6.0 and an apparent Km of approximately 133 mM for sucrose. The enzyme required potassium phosphate for maximum activity, optimum concentration being 250 mM. The enzyme was partially purified by ammonium sulphate precipitation followed by dialysis and separated by molecular exclusion into three components with molecular weights ranging from approximately 40,000 to 55,000.
Proline catabolism, relaxation of osmotic strain and membrane permeability in the diatom Phaeodactylum tricornutum
Authors: SCHOBERT BRIGITTE
Published: April 2006

The influence of osmotic stress on proline catabolism in the diatom Phaeodactylum tricornutum and the fate of proline after relaxation of osmotic stress are described. The conversion of 14C‐proline into metabolic products is greatly inhibited during water stress conditions. A sudden reversal of osmotic stress from 1.9 to 0.77 osmolar in the algal medium leads to a rapid decrease of the cellular proline concentration. This is mainly due to a release of proline into the outside medium of the algal cells, caused by a temporary breakdown of selective permeability in the plasmamembrane. The magnitude of membrane leakage depends on the concentration differences applied. It is supposed that the altered barrier properties reflect an increase in membrane fluidity, as a consequence of osmotic downshock. A replacement of NaCl by KCl, during continued osmotic stress, leads to a rapid and irreversible breakdown of selective permeability in the plasmamembrane. This effect might be due to a special lipid composition of the plasmamembrane or caused by an influence on the membrane potential.