bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism
Authors: Wichner Siegfried , Libbert Eire 
Published: April 2006

AbstractProofs of different kind are presented of the existence of highly active bacteria producing IAA from tryptophan on plant surfaces and in plant homogenates.Both homogenates and washing solutions of nonsterile pea plant parts are active in producing IAA from tryptophan. Activity is much enhanced by the addition of glucose or by preincubating the preparations; it is abolished by sterile filtration, by some bactericidic and bacteriostatic substances, by chloramphenicol, streptomycin, and albucid (penicillin being only partly effective). Preparations of sterile plants do not produce IAA from tryptophan within the detection limit of the Salkowski test. The bacteria are even present on seed surfaces, in the air, and in aceton or ammonium sulfate precipitations of homogenates.Main products of the bacterial tryptophan conversion, as demonstrated by paper chromatography, are indolepyruvic acid, indoleacetic acid, indolecarboxaldehyde, and indolecarboxylic acid. In presence of glucose indolepyruvic acid is by far dominating.Many hitherto known results about tryptophan conversion to IAA by higher plants are likely to be falsified by epiphytic bacteria.
How Mangroves Desalinate Seawater
Authors: Scholander P. F. 
Published: April 2006

AbstractWater relations of a number of mangroves and other halophytes were studied. All mangroves had high negative pressure in the xylem (30 to 60 atm) which more than balances the osmotic pressure of the seawater (25 atm). Freezing a short stem section of an attached twig always resulted in wilting caused by eavitation of the tensile sap. Semipemeable membranes in the leaves remained functioning in spite of being iced or healed (50°C), or being poisoned by dinitrophenol and carbon monoxide (13 atm). Chloroform and ether ruptured the membranes.When some 40 atm pressure was applied to the root system of a decapitated seedling potted in seawater, a flow of nearly fresh water ensued. This separation kept on for hours in spile of chilling and poisoning with dinitrophenol or 20 atm carbon monoxide. A reversal of the gradient made roots lose water to the seawater. One may conclude, therefore, that mangroves separate fresh water from the sea by a simple non‐metabolic ultrafiltration process, in a system where high tension obtains in the xylem and where turgor of the living cells is produced by an active maintenance of high solute pressure.
Growth Inhibition and Recovery in Roots Following Temporary Treatment with Auxin
Authors: Hejnowicz Z. , Erickson R. O. 
Published: April 2006

AbstractContinuous recording (streak photography) of elongation of roots treated with IAA (10–6–10–7M) showed that removal of IAA from the nutrient solution resulted in a rapid resumption of elongation, unless the IAA treatment was shorter than 60 min. If it was shorter, the recovery was delayed, so that it occurred about 1 hour after the beginning of the treatment, independently of the duration of the treatment, down to 4 min. This behavior of roots was observed in all the species investigated (corn, pea, sunflower, onion), also in response to NAA and 2,4‐D. This time lag in recovery of elongation after brief auxin treatment is discussed in connection with the radial concentration gradient of auxin in the root imposed by external auxin. The possible role of a radial gradient of auxin (concentration decreasing with distance from the center) in the control of root elongation is suggested.
Effects of Extended Periods of Osmotic Stress on Water Relationships of Pepper
Authors: Janes Byron E. 
Published: April 2006

AbstractPepper plants grown to uniform size in a controlled environment were subjected to an osmotic stress for periods of 1 to 10 days. Polyethylene glycol 400 was used as the osmotic agent.Leaf area of the plants, grown under uniform conditions, was proportional to the weight of the plants. This relationship was not altered by reduction in rate of growth due to a decrease in osmotic potential of the nutrient solution.The rate of transpiration of the pepper plants decreased as the osmotic potential of the nutrient solution was decreased. The reduction in rate of transpiration was most rapid when the osmotic potential was reduced from −0.5 to −7.5 bars. There was continued reduction in the rate of transpiration with change in potential to −12.5 bar but this change was less than that at the higher potentials. The rate of transpiration remained at a reduced rate for as long as the plants were growing in the solution with low osmotic potential. Alternating the osmotic potential of the nutrient solution between −0.5 and −5.0 bar did not change the response to the −5.0 tension. The reduction in rate of transpiration resulting from the lowering of the osmotic potential by addition of NaCl was similar to that produced by addition of polyethylene glycol.Water potential, osmotic potential, relative water content and stomatal movement were all in dynamic equilibrium with the water content of the leaves. The water content of the leaves was regulated by the supply and demand. In these investigations the demand remained constant. The supply was altered by decreasing the difference in water potential between leaf and substrate and by an increase in resistance to flow of water in the roots as a result of the decrease in osmotic potential of the nutrient solution.
Changes in Nicotinic Acid Content and Its Nucleotide Derivatives of Rice and Wheat Seeds during Germination
Authors: Mukherji Subhendu , Dey Bharati , Sircar S. M. 
Published: April 2006

AbstractRelative distribution of bound and free forms of nicotinic acid in rice and wheat seeds and their metabolism during germination were the subject of the present investigation. Measurement of the levels of NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate) formed another part of the work.Total nicotinic acid in both rice and wheat increased with germination and was maximum at 72 hours. From this time onwards, it began to decline rapidly and at the end of experiment, i.e., after 120 hours, it was lower than that for ungerminated seeds on per seedling basis, although it was slightly higher on per g dry weight basis.Ungerminated seeds of wheat and rice contained about 89 per cent and 80 per cent respectively of their total nicotinic acid in bound form which became partially free in course of germination.Total nucleotides (oxidised plus reduced forms) increased progressively up to 96 hours followed by a slight fall at 120 hours. NAD reached a maximum at 24 hours and fell gradually thereafter. The depletion of NAD was associated with a progressive accumulation of NADH. NADP decreased from the peak value at 72 hours. Formation of NADP and its maintenance at high level depend on NAD in the oxidised form and the content slowed down in tissues with higher NADU/NAD ratio. A relatively large amount of NADPH was present throughout the experiment.
Integrity and Respiration of Red Beet Mitochondria Isolated and Examined in Different Sucrose Concentrations
Authors: Christiansen K. 
Published: April 2006

AbstractRespiration experiments with succinate as substrate were made with red beet mitochondria isolated in soluitions containing 0.25 to 1.25 M sucrose. The respiration was measured in reaction media adjusted to be 0.25, 0.50, 0.75 or 1.0 osmolar.With mitochondria isolated in 0.25 or 0.50 M sucrose the rate of succinate oxidation was completely dependent on the osmotic pressure of the reaction medium (decreasing with increasing osmotic pressures). Isolation in 0.75 M sucrose caused a slight after‐effect of the osmotic pressure of the isolation medium, and by isolation in 1.0 M or 1.25, M sucrose the after‐effect was complete. The rate of oxidation was low and independent of the osmotic pressure of the reaction medium.An electron microscopic examination of the state of the mitochondria before and after the respiration period showed that with the conditions used in the present experiments the structure of the mitochondria remained well preserved regardless of the osmotic pressures used.
Oxygen Diffusion from the Roots of Woody Species
Authors: Armstrong W. 
Published: April 2006

AbstractApplication of the‘polarographic’ technique for studying oxygen diffusion from roots has provided preliminary results which establish that oxygen passes through the woody species Salix atrocinerea Brot., Salix fragilis L., Salix repens L., and Myrica gale L., in the gaseous phase as it does in other wetland species. Entry into the shoots occurs through the bark directly above the water table and in the willow cuttings the effective length of shoot for gas intake was the basal three centimetres above the water table. The length of shoot involved was longer in Myrica gale and the roots were of the normal (un‐nodulated) type.Trials on Alnus glutinosa (L.) Gaertn. provided no conclusive results and it is thought that this was perhaps because measurements were on nodulated roots only.
Seasonal Rhythm of Rooting of Salix atrocinerea cuttings
Authors: Vieitez E. , Peñta J. 
Published: April 2006

AbstractThe response of rooting and the content of growth substances in Salix atrocinerea cuttings were studied every month throughout the whole year. To study the rooting response 100 cuttings were put into a rooting mist‐propagator frame and the results were observed 30 days later. The hormone content was studied with the same type of cuttings by means of methanol extraction, fractionating into acid, basic and neutral substances and chromatographic analysis on paper and bioassays.Salix atrocinerea cuttings have three rooting phases: one very active in January, February, March and April with plentiful roots, not ramified, originating at the base of the cutting; a second lesser phase from May to August with numerous small and very ramified roots formed at a more ample area on the stalk. Both peaks are separated by a sharp fall in June. From September to December the third phase of rooting takes place. Response is practically nil and the few small roots formed are originated at the base of the stalk, again, as in the first phase.In the histograms a remarkable activity in the acid fraction at Rf = 0.30–0.50 was found and IAA was identified. The rooting capacity of these cuttings and the IAA content show some correlation but not exact enough to assert that the root response is governed by an optimum hormonal content.In Salix atrocinerea cuttings inhibitors are absent during the whole year which support the hypothesis that root formation might in some cases be influenced also by the presence or absence of inhibitory growth substances.
Growth Curves and pH‐Optima for Cyanide Producing Bacteria
Authors: Wissing Feode 
Published: April 2006

AbstractHydrogen cyanide producing bacteria of the genus Pseudomonas were isolated and cultured so that activity could bo maintained under laboratory conditions. Formation of cyanide is influenced by the type of Carbon source and the amino acids contained in the media. The bacteria produced most cyanide when grown on succinate plus glycine methyl ester and on glucose plus glycine and D, L‐methionine. pH‐Optima for the production of cyanide by lyophilized bacteria were found to be 8.3 with Tris/HCI buffer.
The Correlation of Physiological Differences and Varions Leaf Forms of an Aqnatic Plant
Authors: Gaudet John J. 
Published: April 2006

AbstractAn analysis of the celluar constituents of the leaves of an aquatic fern, Marsilea vestita, was done after and during the formation of different leaf forms.Land leaves of Marsilea produced almost twice as much dry material, soluble carbohydrate, insoluble protein and soluble peptides compared to submerged leaves on a fresh weight basis, but on a dry weight basis there is tittle difference between the two types of leaves. the submerged leaf soluble nitrogen fraction consisted mostly of ammonia and free amino acids, while that of the land leaf probably con tained mostly peptides. Free arginine was present in large quantities in megaspores and as the plant matured, at the expense of the megaspore, the amount of arginine left in the pool diminished. A correlation was found between soluble sugar increase and leaf elongation, Just prior to the production of submerged leaves the developing leaves contained low levels of protein and soluble sugar, but high levels of soluble nitrogen and an increased amount of starch. A theory which involves metabolism was proposed to account for the leaf form changes in Marsilea.
Action Spectra for the Transient and the Normal Photosynthetic Oxygen Evolution in Wheat Leaves
Authors: Egnéus Hans 
Published: April 2006

AbstractAn action spectrum within the wavelength region 430–700 nm has been determined for an oxygen Iransient isolated from the main photosynthetic oxygen evolution in wheat leaves. the spectrum follows the absorption spectrum of chlorophyll b.In order to compare this oxygen evolving process with the normal photosynthetic oxygen evolution, an action spectrum for this later process was also determined but only in the wavelength region 600–700 nm. This action spectrum closely corresponds to other action spectra for the photosynthetic oxygen evolution found in the literature.The behaviour of the oxygen transient after various treatments was also studied. It was found that the transient oxygen evolution was influenced by the dark period between irradiations, and by a previous irradiation with a wavelength longer than 695 nm, both conditions having a promoting effect on the oxygen evolution.The action spectra and the other findings are discussed on the basis of the two‐pigment hypothesis.
Lipids in Cruciferae
Authors: Appelqvist Lars‐Åarke 
Published: April 2006

AbstractDiploid and tetraploid types of white mustard (Sinapis alba) and turnip rape (Brassica campestris), annual and biennial forms, were grown in Turkey and in Sweden. Seed weight and oil content were measured and fatty acid composition determined by gas chromatography.Polyploidization of all cultivars effected an increase in seed size but did not markedly change the oil percentage or fatty acid composition.Growing conditions in Turkey caused an over‐all decrease in seed size although the oil content was reduced only in the spring Turkish plantings. Fatty acid composition was influenced by the environment to a small but probably significant extent in all cultivars. For Swedish and Turkish winter turnip rape the mean content of oleic acid was 13.7 per cent and 15.8 per cent, of linolenic acid 9.5 per cent and 8.6 per cent, of erucic acid 45.7 per cent and 42.4 per cent, respectively; no consistent differences were observed for linoieic acid. Similar differences were observed for summer turnip rape and white mustard. Thus the warmer and drier Turkish climate favoured a higher oleic acid, lower linolenic and erucic acid content, i.e. a reduction in the per centage of the major end products of fatty acid biosynthesis.
Biosynthesis of Thiazole in Exobasidium
Authors: Sundström Karl‐Ragnar 
Published: April 2006

AbstractIn some Exohmidium strains, which grow on a synthetic medium containing glucose citralc, and thiamine as the only organic compounds, growth usually does not start until after more than 800 honrs if thiamine is replaced by pyrimidine.Homocysteine and methionine are able to shorten this lag phase of E. vaccinil“myrt.” Methionine is growth‐promoting only at about pH 4. At low concentrations the yield is proportional to the concentration of methionine. Growth ceases when the methionine is consumed and the fungus then enters a lag phase as long as that in methionine‐free medium. Methionine does not indnce the thiazole‐synthesizing enzymes, but is probably consumed as a precursor of thiazole.The utilization of this precursor is delayed by some growth factors and amino acids, i.e. cholin, betaine, glutamic acid or glutamine. The delayed adaptation of the methionine‐ and thiazole‐synthesizing enzymes seems to be regulated by changes in the nutritional state of the ageing cultures. The mechanism of this regulation has not been settled.
The Effect of Prevention of Flowering on the Vegetative Growth of Inoculated Pea Plants
Authors: Roponen Ilma E. , Virtanen Artturi I. 
Published: April 2006

AbstractThe removal of the apical buds from the top of inoculated pea ptants before flowering caused the axillary buds of the stem leaves to develop and thus further to branch. The vegetative growth of the test plants continued to be luxuriant when blooming was delayed. While the control ptants formed seeds and ripined. the vegetative growth of the stem of the test ptants increased at most eight‐fold during the same time. A new, additional red part grew at the same time in the root nodules, which had already partly become green. The new red part branched later so that the imusuatty large nodules appeared quite odd. The weight of the branched, large nodules had at the same time increased on the average six‐fold and the vegetatively grown test plants synthesized even eight times more nitrogen than did the control plants. The concentration of teghaemoglobin in the nodules formed by the bacterial strain used in the experiment was not inereased, but the absolute amount of the pigment was raised six‐fold as a result of the increased nodule mass. While the vegetative growth was going on, oxidation of the leghaemoglobin was delayed.Analyses of nitrogen and amino acids were made for both test and control plants.The total length of the branches in the largest test plant was 32 m compared with the unbranched control plant which was 1.30 m.
Trehalose, Respiration und Photosynthese in dem Farn Ophioglossum, Ein neuer Schattenblattypus
Authors: Löhr Erika 
Published: April 2006

Abstract Trehalose, Resipration and Photosynthesis in the Fern Ophioglossum. A new Type of Shade‐Leaves.—Trehalose has been identified in the leaf‐blades, sporehouses, stems and rhizomes of the fern Ophioglossum vulgatum by paper chromatography. The leaf‐blades represent a hitherto undescribed type of shade‐leaf. Just like normal shade‐leaves, they have a low respiratory activity ∼0.2–0.3 mg CO2 per 50 cm2 leaf‐blade (one side only) and hour at 20°C and low maximal photosynthesis: 2–2.7 mg CO2 per 50 cm2 leaf‐blade (one side only) and hour at 20°C and a CO2‐pressure of 0.25 mm Hg and a light intensity of 20,000 lux. But in contrast to the hitherto described type of shade‐leaves, the area per 1 g fresh weight is that of typical sun‐leaves which is 35–50 cm2 (one side only) per 1 g fresh weight. The large area weight is connected with particularly low dry matter content ∼10–11 per cent in the leaf‐blades; this indicates that the material is a kind of semisucculent shade‐leaf.
Leaf Factors Affecting Light‐Saturated Photosynthesis in Ecotypes of Solidago virgaurea from Exposed and Shaded Habitats
Authors: Holmgren Paul 
Published: April 2006

AbstractPlants of Solidago virgaurea L. from exposed and shaded habitats differ with respect to the response of the photosynthetic apparatus to the level of irradiance during growth. An analysis was carried out on leaf characteristies which might be responsible for the differences established in the rates of Hght‐saturated CO2 uptake. The clones were grown in controlled environment chambers at high and low levels of irradiance. Light‐saturated rates of photosynthesis and transpiration were measured at natural and lower ambient CO2 concentrations.A low temperature dependence of light‐saturated CO2 uptake at natural CO2 concentrations, and a strong response to changes in stomatal width, suggested that the rate of CO2 transfer from ambient air towards reaetion sites in chloroplasts was mainly limiting the pholosynthetic rate. Resistances to transfer of CO2 for different parts of the pathway were calculated. There was a weak but significant correlation between stomatal conductance and the product stomatal frequency ± pore length. Mesopbyll conductance and dry weight per unit area were highly correlated in leaves not damaged by high irradiance. This suggests that mesophyll conductance increases with increasing cross sectional area (per unit leaf area) of the pathways of CO2 transfer in the mesophyll from cell surfaces to reaction sites.The higher light‐saturated photosynthesis in clones from exposed habitats when grown at high irradiance than when grown at low irradiance was attributable mainly to a lower mesophyll resistance. In shade clones the effect upon CO2 uptake of the increase in leaf thickness when grown at high irradiance was counteracted by the associated inactivation of the photosynthetic apparatus. The difference in CO2 uptake present between clones from exposed and shaded habitats when preconditioned to high irradiance resulted from differences in both mesophyll and stomatal resistances. A few hybrid clones of an F1‐population from a cross between a clone from an exposed habitat and a clone from a shaded habitat reacted, on the whole, in the same way as the exposed habitat parent. When grown at high irradiance, the hybrid clones showed higher photosynthetic rates than either parent; this was largely attributable to the unusually low stomatal resistance of the hybrid leaves.
An Evaluation of Specific and Non‐Specific Inhibition of 2‐Dimensional Growth in Fern Gametophytes
Authors: Miller John H. 
Published: April 2006

AbstractGametophytes of Onoclea sensibilis were grown under continuous white light of 90 lux. Filaments were produced having 4–6 cells before the initiation of 2‐dimensional growth. There was a close correlation between the average cell number of a population of plants and the proportion of 2‐dimensional forms. 8‐Azaguanine produced a general inhibition of growth, and it was shown that the reduced proportion of 2‐dimensional plants caused by 8‐azaguanine was a secondary consequence of the general growth inhibition. IAA however gave a true specific inhibition of 2‐dimensional growth.Based on these experiments the proper criteria for establishing a specific inhibition of 2‐dimcnsional growth arc discussed. These criteria are applied in a critical review of previous papers on the inhibition of 2‐dimensional growth. It is concluded that no firm evidence is available that inhibition of protein synthesis specifically blocks 2‐dimensional growth.
Extraction, Assay and Partial Purification of a Factor from Tumorous Leaves that Promotes Crown‐gall Tumor Growth
Authors: El Khalifa M. D. , Lippincott James A. 
Published: April 2006

AbstractA tumor growth factor was extracted from primary pinto bean leaves {Phaseolus vulgaris L. cv. “Pinto”) having crown‐gall tumors. Application of these extracts to primary pinto bean leaves at day 3 after inoculation with Agrobacterium tumefaciens (Smith and Town.) Conn resulted in an increase in the diameter of tumors on these leaves after 24 hours that was 25–60 percent greater than that of the controls. No growth promoting activity was detected in comparable extracts from control leaves or from cultures of the bacterium. The tumor growth factor did not affect tumor number when applied in this fashion. The active extracts were fractionated on Sephadex (1–15 columns and an active component obtained which eluted in a volume suggesting a molecular weight in the range of 100–200. A spectrum of the material in this fraction is shown and some of the characteristics of this material are described. Reasons are presented for considering this growth factor to be identical with at least one of the growth factors previously hypothesized to account for the greater tumor growth observed as tumor number is increased in this system.
The Effect of Limitation in Light During the Rest Period On Leaf Bud Break of the Peach (Prunus persica)
Authors: Erez A. , Lavee S. , Samish R. M. 
Published: April 2006

AbstractReduction in the amount of light supphed during the mid‐rest period caused a hetter leaf bud opening in the peach as compared with natural winter daylight; this includes darkness, short photoperiod and reduced light intensity. The quantitative nature of this light effect was shown. The role of light as a factor regulating dormancy is discussed.