bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence relative de la BAP et de l'IBA sur la néoformation de bourgeons et de racines sur les plantules du Biota orientalis (Cupressacées)
Authors: Thomas M. J. , Tranvan H. 
Published: April 2006

Relative influence of BAP and IBA on the induction of adventitious buds and roots on plantelts of Biota orientalis (Cupressaceae)Both cytokinin (BAP) and auxin (IBA) have an influence upon the intensity of adventitious bud induction in vitro on hypocotyls of Biota orientalis.Increase in either the concentration or the length of contact with cytokinin enhances the mean number of neoformed buds per explant, while that of auxin results in an increase of the mean number of reactive explants as well as in the nature of neoformations. Auxin contributes to a restoration of the induction when the length of contact with cytokinin is too short. However, this synergism is only observed when the contract with IBA is simultaneous or follows that with contract with BAP.Rhizogenesis is also influenced by the auxin‐cytokinin balance. An increase in the duration of contact with IBA is always followed by an increased in the mean number of explants forming roots. This organogenesis may be partially or completely inhibited if the duration of contact with cytokinin – before, simultaneously or after that with auxin‐ exceeds two weeks.
Lipid biosynthesis by chloroplasts from olive tree leaves
Authors: Daza Luis M. , Donaire Juan P. 
Published: April 2006

In vitro incubation of isolated chloroplasts from young olive tree leaves (Olea europaea L. cv. Marteño) in acetate‐1‐14C showed a high labelling of saturated fatty acids (palmitic + stearic) and, above all, of the monounsatured ones (oleic); the low biosynthetic rate of α‐linolenic acid being noteworthy. These fatty acids are mainly found as free ones, or incorporated in mono‐and diglyceride molecules. Phosphoand galactolipids, the most abundant acyl‐lipid components of chloroplast lamellae, showed low incorporation rates. The fatty acid synthesis by isolated chloroplasts depends on exogenous CoA, ATP, NADPH and, especially, on added ACP (acyl carrier protein) preparation from Escherichia coli, whereas it was strongly inhibited by Triton X‐100.In vivo experiments with acetate‐1‐14C infiltration into young excised leaves showed a high labelling of chloroplast phospholipids, but a low 14C incorporation into galactolipids, a remarkable feature because these latter are main components of chloroplast lamellae. The high biosynthetic rate of α‐linolenic acid is noteworthy and appears mainly linked to monogalactosyldiglycerides. Also the low incorporation of saturated fatty acids to neutral lipids is remarkable. The low in vitro synthesis of α‐linolenic acid in comparison with that of the in vivo conditions, suggests the existence of a cooperation between chloroplasts and other parts of the cell to carry out the synthesis of this compound.
Physiological and biochemical changes associated with cotton fibre development
Authors: Naithani S. C. , Rao N. Rama , Singh Y. D. 
Published: April 2006

Growth kinetics and levels of auxin substances were studied in three cotton cultivars, designated as long, medium and short staple cultivars. Fibre length and dry weight plotted against boll age showed sigmoidal patterns and were fitted to a logistic curve by computer curvilinear regression analysis. The final length of the fibre in different cultivars was the product of the rate of elongation per day and the total period of elongation. Further, considerable overlap between the elongation and the secondary thickening phases was recorded.No relationship between auxin substances and rate of fibre elongation was discernible. The peak levels of auxin substances in all the cultivars were recorded before or about the time when elongation had just started, and it is concluded that the auxin synthesized during the elongation phase is consumed in elongation growth. Thus there is necessarily no relationship between remaining auxin and growth.
Long‐term effects of low levels of SO2 on bean plants (Phaseolus vulgaris). II. Immission‐response effects on biomass production: quantity and quality
Authors: Saxe Henrik 
Published: April 2006

Bean plants (Phaseolus vulgaris L. cv. Processer) were grown in water culture with separate air supply to roots for four to five weeks at five levels of SO2 ranging from 10 μg m−3 to 950 μg m−3. At harvest the plant material was divided into six fractions: root, stem, fruit and leaves of three age groups.Plants were mainly affected at and above approx. 250 μg m−3 SO2. Fresh weight was reduced in mature and old leaves, and roots and fruit. Dry weight was also reduced in mature and old leaves, and roots and stem. A reduction was found in chlorophyll a and chlorophyll b in mature and old leaves, and also starch was reduced in the leaves. Sulfur content of leaves and fruit increased with exposure time and concentration, while Br, Ca, Cl, K, Mn, P and Zn increased at the highest SO2 level only. Total (but not specific) peroxidase activity increased in all aerial fractions, i.e. soluble protein increased just like peroxidase activity. Seventeen studied amino acids all increased on the average by 38% in mature bean pods.The observed effects may be parts of a reaction for survival and propagation of the plant, as fruit quality was not affected, indeed, it sometimes improved slightly. The latter observation is of commercial interest.
Mise en évidence ?amines liées à des structures cellulaires chez Nicotiana tabacum et Lycopersicum esculentum
Authors: Vallée J. C. , Vansuyt G. , Négrel J. , Perdrizet E. , Prévost J. 
Published: April 2006

Demonstration of amines connected with cellular structures in Nicotiana tabacum and Lycopersicum esculentum.The level of free and bound amines in various tissues of Nicotiana tabacum cv. Xanthi was investigated. After acid hydrolysis of different pellets from ethanol or buffer extractions, three aliphatic polyamines (putrescine, spermidine, spermine) and one aromatic monoamine (tyramine) were found in different proportions according to the nature of the tissue. Roots contain high quantities of insoluble tyramine bound very strongly to cellular structures. On the contrary, there were only traces of bound tyramine in leaves and stem. After extraction and purification of cell structures, tyramine was shown to be bound to one component of the cell wall. Addition of pronase or cellulase to the extract did not break the tyramine complex. In tobacco roots, insoluble tyramine concentration increased with plant development. High content of bound tyramine was also found in Lycopersicum esculentum roots. The possibility that tyramine binds with lignin is discussed.
Water deficit enhancement of proline and α‐amino nitrogen accumulation in potato plants and its association with susceptibility to drought
Authors: Levy David 
Published: April 2006

Potato plants (Solanum tuberosum L. cvs ‘Up‐to‐Date’, ‘Desiree’, ‘Alpha’, ‘Spunta’, ‘Elvira’ and ‘Troubadour’) were exposed to cycles of water stress and relief during growth. Severe water deficit induced increased proline content 6‐ to 7‐fold in nonturgid leaves which just started to wilt, and 8‐ to 27‐fold in fully wilted leaves of potatoes. However, proline content was not affected during the early stages of stress development over a range of osmotic potentials in the leaves. The rising proline content was related to turgor loss of leaves independent of changes in the osmotic potentials, which indicates that proline involvement in osmoregulation of potato leaves is unlikely.Repeated cycles of water stress and relief resulted in increased proline and α‐amino nitrogen content in the tuber tissue of some of the cultivars. The smallest increase in proline content was obtained in ‘Alpha’ tubers and the content of α‐amino nitrogen remained unaffected by the water stress. Concomitantly, ‘Alpha’ was the most drought‐tolerant cultivar, as determined by its capacity to accumulate dry matter in tubers under stress conditions. On the other hand, in tubers of cultivars which were more susceptible to drought, a marked increase in proline and α‐amino nitrogen was observed in response to water stress. The possible association of these findings with tolerance of potatoes to repeated short periods of drought is discussed.
Varietal differences in the toxicity of sodium ions in rice leaves
Authors: Yeo A. R. , Flowers T. J. 
Published: April 2006

Visual damage is commonly used as the criterion for assessment of salinity resistance in rice breeding programmes. The use of other indicators, such as sodium uptake, is being evaluated: a correlation between initial sodium uptake to the third leaf and varietal survival was established and the physiological basis of this examined.Chlorophyll was used as an indicator of metabolic status and the relationship between leaf sodium and chlorophyll concentrations investigated for nine varieties differing in their resistance to salinity. By sampling a population of leaves having a wide range of salt concentrations, inverse relationships between chlorophyll and sodium concentrations were established. The salt concentration in the leaf tissue which causes equivalent toxicity (50% loss of chlorophyll) differed 3‐fold amongst these varieties. Varieties showing the greatest tolerance to salt within the leaves were not necessarily those showing the greatest overall phenotypic resistance to salinity.The enzymes malate dehydrogenase and nitrate reductase were activated equally by sodium and potassium ions at 60–80 mol m−3 in both control and saline grown plants and severely inhibited at higher concentrations. If all the salt in the tissue of leaves with 50% chlorophyll remaining was in solution and uniformly distributed the concentration would be 135–500 mol m−3. This is improbable and some level of compartmentation is likely.It is concluded that while initial sodium uptake has predictive value for salinity resistance of varieties, there are other characteristics which are masked by excess salt entry and require independent assessment; no single factor confers resistance.
Genetic differentiation in Plantago major: Growth and root respiration and their role in phenotypic adaptation
Authors: Kuiper Daan 
Published: April 2006

The root respiration and the growth of plants of four inbred lines of Plantago major L. were followed at two levels, of mineral nutrition. In addition the response to a transfer of plants from one condition to the other was studied. The activities of the cytochrome and of the alternative pathway wee determined and used to distinguish between genetic differences among the inbred lines and the plasticity within each inbred line. Root respiration and growth parameters differed significantly between the lines and were directly related to seed number per capsule (low respiratory activity and slow growth – 11 seeds per capsule; high respiratory activity and fast growth – 33 seeds per capsule).Plasticity of respiration and growth parameters is expressed as differences in the total respiration, the activities of the cytochrome and of the alternative pathway, and in the shoot to root ratio, as a response to nutritional level or to changes of the strength of the nutrient solution. Differences in this plasticity in the four selected lines and in quickness of response to a change in mineral nutrition were directly related to the ecological strategy. These results are discussed in relation to the strategy of the genotypes for survival in the field. The high growth rate and the presence of plasticity in line 4 (ssp. Pleiosperma) make this genotype act like an annual, following a ruderal strategy. The lower growth rate and the absence of plasticity in line 1 (ssp. major) fit a more competitive strategy.
Relationships among nitrogen accumulation, nitrogen assimilation and plant growth in chrysanthemums
Authors: Elliott George C. , Nelson Paul V. 
Published: April 2006

Relationships among growth, N accumulation and assimilation were investigated in Chrysanthemum morifolium Ramat cv. Fiesta in experiments testing the effects of varying levels of NO–33supply and of increasing NH+4 added to a constant level of NO–33 Flowing solution culture systems were used to provide NO−3at concentrations of 0.03 to 5.0 mol m–3 and NH+4 levels from 0.05 to 0.3 mmol m–3 added to 0.1 mol m–3NO−3. Rates of growth, N absorption, accumulation, distribution and utilization were estimated by regression analysis of data obtained from sequential plant harvests, and rates of NO−3 and NH−4 net uptake were estimated from solution depletion.A sustained ambient NO−3 concentration of 0.03 mol m–3 was evidently adequate to support growth, since relative growth rates were not affected by increasing NO−3 supply from 0.03 to 1.0 mol m–3, nor from 0.25 to 5.0 mol m–3, in separate experiments. Shoot growth rates were stimulated by NH4 added to NO−3 one experiment, but not when the experiment was repeated under ambient conditions less favorable to growth.Relative accumulation rates for total N increased with increasing NO−3 and with NH+4added to NO−3 A constant proportion of NO−3 taken up was reduced when NO−3 alone was supplied. Both the proportion of total N taken up as NO−3 and the proportion of NO−3 reduced decreased with increasing NH+3 added to NO−3 NH+4 uptake apparently must exceed a threshold of about 30% of the total uptake to inhibit NO−3 uptake.Utilization of N in chrysanthemum was apparently limited by redistribution since relative accumulation rates for total N were equal to or greater than relative growth rates, in contrast to results reported for several other species. Results of this study and other information support the postulate that NH+4 added to NO−3might stimulate growth by increasing transport of reduced N from roots to shoots, thus increasing the supply of reduced N available to support growth of shoot meristems.
Protein synthesis by chloroplasts during the senescence of barley leaves
Authors: García Sebastián , Martín Mercedes , Sabater Bartolomé 
Published: April 2006

Chloroplasts were isolated from senescent leaf segments of barley (Hordeum vulgare L. var. Mozoncillo) and assayed for protein synthesis. Protein synthesis activity of the chloroplasts greatly increased after 10–20 h of incubation of leaf segments in the dark in spite of an intense degradation of chloroplast rRNA. The rise in the activity of protein synthesis was more pronounced when kinetin was present in the incubation medium. However, as deduced from SDS‐polyacrylamide gel electrophoresis of the products, different proteins were synthesized under the two conditions of incubation of the leaf segments. The activity of protein synthesis of the chloroplasts decreased during the first hours of incubation of the leaf segments in the light.Cutting and incubation in the dark of the leaf segments enhanced the synthesis of a few proteins also formed by chloroplasts in attached senescing leaves. Hormone and senescence treatments changed the type and the rate of the protein synthesized by chloroplasts, which suggests that hormones may control senescence through a modulation of the protein synthesized by the chloroplasts.
Acides‐aminés et amines libres ?explants foliaires de Nicotiana tabacum cultivés in vitro sur des milieux induisant la rhizogenèse ou la caulogenèse
Authors: Malfatti H. , Vallée J. C. , Perdrizet E. , Carré M , Martin C. 
Published: April 2006

Free amino acids and amines in leaf explants of Nicotiana tabacum cultivated in vitro on media inducing rhizogenesis or caulogenesis.Foliar explants of Nicotiana tabacum cv. Xanthi n.c. were cultivated on three different media: (1) a basal medium without hormone, so that no differentiation occurred in the explants; (2) with auxin added; and (3) with auxin plus cytokinin added, where the additions (2) and (3) promote rhizogenesis and caulogenesis, respectively. The content of free amino acids and amines of the three kinds of explants were investigated. In the two media lacking cytokinin, the explants contained great amounts of five amino acids (asparagine, glutamine, proline, glutamic acid and histidine) and of one aromatic amine, tyramine. In the cytokinin containing medium, only two amines accumulated in the explants: one aliphatic polyamine (putrescine) and one aromatic amine (phenethylamine). The increase in amino acids began immediately on the first days of culture. It was related neither to a more active proteolysis nor to the breaking of the correlations from the mother plant. It was induced by the addition of nutritional elements into the medium. On the other hand, the accumulation of aromatic amines occurred after a few days of culture and was transitory. A decrease was observed after the first emergence of new organs. The relation between the accumulations of these aromatic compounds and formation of roots or shoots is discussed.
Lipid composition of prolamellar bodies and prothylakoids of wheat etioplasts
Authors: Ryberg Margareta , Sandelius Anna Stina , Selstam Eva 
Published: April 2006

Prolamellar bodies and prothylakoids were fractionated from etioplasts of wheat (Triticum aestivum L., cv. Starke II, Weibull) and characterized with emphasis on lipid composition. The two fractions contained the same lipid classes. Glycolipids (monogalactosyl diacylglycerol, digalactosyl diacylglycerol, and sulphoquinovosyl diacylglycerol) were the dominating complex lipids. Phospholipids (mainly phosphatidyl choline and phosphatidyl glycerol) constituted between 10 and 15 mol% of the total amounts of polar lipids. Free sterols and sterol esters were present in low amounts (ca 6 mol%). Saponins could not be detected. The contents of glycolipids and protochlorophyllide were higher in the prolamellar body fraction than in the prothylakoid fraction on a protein basis, as was the protochlorophyllide content on a glycolipid basis. The molar ratio of monogalactosyl diacylglycerol to digalactosyl diacylglycerol was higher in the prolamellar body fraction (1.8) than in the prothylakoid fraction (1.2).Since the same chemical constituents were found in the two membrane fractions we propose that the difference in ultrastructure between prolamellar bodies and prothylakoids is due to different relative amounts of lipids (glycolipids), protochlorophyllide, and proteins in the two membrane systems.
Sporulation et mycosporines chez un champignon imparfait: Ascochyta fabae
Authors: Pittel Jean‐Louis , Bourguignon Brigitte , Arpin Noël 
Published: April 2006

Sporalation and mycosporins in the Deuteromycete Ascochyta fabae.To investigate the sporogenic activity of mycosporins, a strain of Ascochyta fabae Speg., in which conidiogenesis and mycosporin synthesis are easily induced, has been selected. In darkness, few mature pycnidia and little mycosporin are produced. Dry weight and mycosporin production were followed during mycelial growth and the conidiogenic phase, in both illuminated and non‐illuminated cultures: Mycosporin production appears closely linked with the morphogenic differentiation; its synthesis starts when the exponential growth is over. There is a good correlation between conidiogenesis and mycosporin production.Irrespective of illumination, there is no increase in the rate of sporulation when maycosporins are added at different concentration levels. This cannot be explained by impermeability of the hyphae to mycosporins since uptake starts after a lag phase of 7 days and then proceeds until 15 to 20 days; at the same time the mycelium of A. fabae keeps its sporulation competence until 16 days after transfer to complete darkness. Mycosporin accumulated into conidiospores – 3 to 5% of dry weight – is not metabolized during the germination; on the contrary, a slight synthesis occurs after 20 h of germination.Mycosporins thus seem to be secondary metabolites appearing as products from a type of metabolism that occurs at a very low level during mycelial growth and increases its activity during reproductive morphogenesis in numerous species of fungi.
4‐Desmethylsterol composition of citrus rootstocks of different salt exclusion capacity
Authors: Douglas T. S. , Walker R. R. 
Published: April 2006

Fibrous roots from seedlings of three citrus rootstocks (Rungpur lime, Kharna khatta and Etrog citron) grown hydroponically for 6 weeks in the presence or absence of 50 mM NaCl were analysed for their content of free, esterified, and glycosidic sterols. Leaf chloride analyses indicated that Rangpur lime was a good Cl‐ excluder and the other two rootstocks were Cl‐ accumulators.On a dry weight basis and in the absence of NaCI only the free 4‐desmethyIsterol levels showed significant rootstock differences. Kharna khatta had the highest, and Rangpur lime the lowest, free stcrol levels. Sitostcrol was the major component of all sterol fractions of Rangpur lime, the esterified fraction of the other rootstocks, and the glycosidic sterol fraction of Kharna khatta. The ratio of sitosterol to stigmasterol was highest in Rangpur lime and lowest in Etrog citron in all cases and the ratio of apos;more‐planar apos; to apos;less‐planar apos; free sterols was highest in Etrog citron and lowest in Rangpur lime.Treatment with 50 mM NaCI resulted in an increase in free sterol levels in Rangpur lime and a decrease in Kharna khatta. Steryl ester levels were unaffected in Rangpur lime but were significantly reduced in the other rootstocks. In all three sterol fractions the sitosterol/stigmasterol ratio was decreased. A decrease in the ratio of apos;more‐planarapos; to apos;less‐planarapos; free sterols was observed only in Kharna khatta and, more notably, Etrog citron. Salt‐induced changes in the apos;more‐planar apos; to apos;less‐planar apos; free sterol ratio correlated well with salt exclusion capacity.
Correlative changes in sucrose uptake, ATPase activity and membrane fluidity in carnation petals during senescence
Authors: Adam Zach , Borochov Amihud , Mayak Shimon , Halevy Abraham H. 
Published: April 2006

Apparent sucrose uptake. ATPase activity and membrane fluidity changes were studied during the development and senescence of carnation flowers (Dianthus caryophyllus L., cv. Cerise Royallette). Typical changes associated with senescence of a cut flower, such as respiration, ethylene production and fresh weight, were measured. Concomitant with a rise in respiration and ethylene production and a decline in fresh weight, a sharp decrease in apparent sucrose uptake was observed. Sucrose uptake was pH dependent (pH optimum, 5.5) and influenced by membrane integrity. Apparently, the activity of ATPase is related to sucrose uptake, because similar changes occurred during flower development. In addition, the activity of ATPase was well correlated with membrane fluidity.It is suggested that sucrose uptake is controlled by ATPase activity, which in turn is modulated by membrane lipid fluidity. The decline in membrane fluidity associated with senescence leads to a corresponding reduction in ATPase activity and sucrose uptake. Further evidence supporting this view comes from experiments in which senescence was enhanced by 1‐aminocyclopropane‐l‐carboxylic acid. It shortened the time to decline in fresh weight, rise in respiration and ethylene production. In parallel, reduction in membrane fluidity, ATPase activity and sucrose uptake were observed.