bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wall‐protein antibodies as inhibitors of growth and of autolytic reactions of isolated cell wall
Authors: Huber Donald J. , Nevins Donald J. 
Published: April 2006

Antiserum raised against protein prepared from corn (Zea mays L. hybrid B73 X Mo17) seedling cell wall exhibits antigrowth activity and inhibits autolytic reactions of isolated cell wall. The growth of corn coleoptile segments pretreated in wall‐protein antiserum was inhibited 35% compared to tissue which had been exposed to normal serum. Since the cuticle constituted a barrier to the entry of serum protein the coleoptile surface was abraded prior to exposure to the serum. Growth inhibition observed in nonabraded sections (8 to 10%) was apparently the result of the entry of serum protein via the cut ends of the tissue. Subsections recut from the central region of antiserum‐treated, nonabraded coleoptiles responded normally in growth experiments. Antiserum brought in contact with isolated cell wall prior to its use with intact coleoptiles was less effective as a growth inhibitor, which suggested that the antibodies which impede growth responses bind to cell wall.Wall‐protein antiserum also strongly inhibited autolytic reactions of isolated cell wall. Wall treated in normal serum or buffer liberated sugars at a rate of 8.6 μg‐ (mg wall dry‐weight)−1·h−1 while antiserum‐treated wall autolyzed at a rate of 2.6 μg·mg−1·h−1 representing a 70% reduction in autolytic potential. After 24 h yields from antiserum‐treated wall were 50% lower than yields obtained from control wall. The antiserum had no effect on the molecular‐weight distribution of the autolytically‐liberated products, and direct assays of wall‐bound and solubilized endo‐ and exo‐β‐d‐glucanases involved in autolytic reactions demonstrated no significant impairment of their catalytic activity. However, the addition to antiserum‐treated wall of a wall‐protein preparation containing autolytic enzymes resulted in a significant enhancement (132%) in autolytic potential. The evidence suggests that enzyme mobility may be critical in the autolytic hydrolytsis of plant cell wall.
ATP‐levels of germinating seeds in relation to vigor
Authors: Lunn Gorm , Madsen Erik 
Published: April 2006

Determination of seed vigor was attempted by comparing ATP‐levels of deteriorating seed to germination percentage and production of dry matter. Immediately after imbibition of any seed lot investigated, a production of ATP took place. This ATP‐accumulation invariably reached a plateau after 6 h of imbibition. Two well germinating seed lots of rape, one of cauliflower and one of sugar beet, were artificially aged by means of elevated storage temperature and humidity. Every second week through 16 weeks of deterioration the levels of ATP, ADP and AMP after 7 h of imbibition were compared with the germination percentage. While ADP‐ and AMP‐contents of germinating seed displayed no change (when imbibed 7 h) during the period of artificial aging, seed deterioration was reflected in the ATP‐levels long before loss of viability could be detected by the conventional germination test.When ATP‐levels per seed were related to germination percentage throughout the aging, all four seed lots displayed similar patterns although the absolute figures differed. In contrast to the conventional “per seed’ basis, however, ATP per gram seed not only displayed similar deterioration patterns, but the absolute values were also of the same magnitude.
Energy metabolism of Plantago major ssp. major as dependent on the supply of mineral nutrients
Authors: Lambers Hans , Posthumus Freek , Stulen Ineke , Lanting Lineke , van de Dijk Siebren J. , Hofstra Rinie 
Published: April 2006

Plantago major L. ssp. major, a grassland species from a relatively nutrient‐rich habitat, was grown in nutrient‐rich and nutrient‐poor culture solutions. Half of the plants were transferred from high to low or from low to high nutrient conditions. The rate of dry matter accumulation in both shoots and roots decreased slowly upon transfer of plants to low nutrient conditions and the shoot to root ratio was unaffected. The rate of structural growth of both roots and shoots increased upon transfer from low to high nutrient conditions and the shoot to root ratio, if calculated from non‐structural‐carbohydrate‐free dry weights, increased.Photosynthesis was largely independent of the nutrient supply. Root respiration, particularly the activity of the alternative oxidative pathway, decreased with increasing age. This decrease was ascribed to a decreased shoot to root ratio, which reduced the relative amount of carbohydrates translocated to the roots and thus the amount available for the alternative pathway. It is calculated that in young as well as in old plants grown in full nutrient solution 48% of the daily produced photosynthates was translocated to the roots.This is at variance with data on P. lanceolata, where a decreasing proportion of the daily produced photosynthates was translocated to the roots when the plants grew older. It is concluded that shoot growth plus shoot respiration consumed a constant amount of the daily produced photosynthates in P. major and that the rest was left for translocation. It is further calculated that in P. major plants grown in full nutrient solution c. 25% and c. 2% of the daily produced photosynthates in young and old plants, respectively, was respired in a way that is not involved in production of energy that is utilized in growth and maintenance (‘inefficient root respiration’).The results are discussed in comparison with those of P. lanceolata, a species from a relatively nutrient‐poor habitat.
Effects of applying etnylene to the root system of Zea mays on growth and nutrient concentration in relation to flooding tolerance
Authors: Jackson Michael B. , Drew M. C. , Giffard Susan C. 
Published: April 2006

Previous studies have shown increases in the concentration of ethylene in the soil and roots of plants when the soil is water saturated (flooded). In Zea mays L. this occurs in association with an overall reduction in growth but without extensive foliar senescence and in conjunction with the development of an adventitious root system. We have assessed the possibility that ethylene may be involved in these responses to flooding. Mixtures of the gas in air were therefore supplied to the roots and stem‐base of Z. mays growing in nutrient solution.Seven or 14 d exposure to ethylene (1 or 5 νl 1−1) inhibited seminal root elongation and growth in dry weight and accelerated the emergence of adventitious roots, although their final length and dry weight were depressed. Leaf extension was inhibited by 0.1,1.0 or 5.0 μl 1−1 ethylene around the roots; leaves extending rapidiy at the start of treatment were the most sensitive. Final shoot fresh and dry weights were depressed by the gas but tie shootrroot dry weighl ratio and percentage dry matter were not affected greatly. Leaf chlorosis was not observed but the concentration of phosphorus in the shoots was 26 to 31% below normal.When aeration of the nutrient solution was stopped, the concentration of dissolved oxygen declined and the concentration of ethylene in the roots increased. Similar changes occur in response to soil flooding. Root and shoot growth was slowed by non‐aeration although the shootroot dry weight ratio remained unchanged. The phosphorus concentration of the shoots was depressed but there was little chlorosis or leaf death. The similarity in these respects between the effects of ethylene and non‐aeration suggests that in flooded Z. mays, ethylene contributes to their development by accelerating the emergence of adventitioos roots, inhibiting phosphorus accumulation in the shoots and by a non‐toxic inhibition of plant growth.
Intervention de l'oxygène atmosphériqoe sur l'absorption d'eau chez Helianthus annuus
Authors: Lascève G. , Couchat Ph. 
Published: April 2006

The role of atmospheric oxygen on root water absorption in Helianthus annuus. The effect of atmospheric anoxia on root water absorption was studied. The experiments were carried out on intact young sunflowers in controlled temperature, light and gas environment; roots were kept in aerated nutrient solution at constant temperature. The evolution of root water absorption and transpiration rate was measured continuously. Before the experiment, the plant was preconditioned at a high transpiration rate by illumination or by CO2 free air in darkness. Then the atmospheric oxygen was suppressed for 1 h, after which the normal conditions were restored.In anoxia and darkness, the root water absorption cannot balance transpiration, so that an important water stress develops in the plant; the light compensates this effect through the photosynthetic oxygen. The supply of oxygen, in darkness or in light, immediately removes inhibition of stomatal closure and of root water absorption. Two mechanisms control water absorption by roots: the fast one occurs in the leaves and the slower one cannot develop without the root system.
Role of sugars in nitrate utilization by roots of dwarf bean
Authors: ten Cate Charlotte H. Hänisch , Breteler Hans 
Published: April 2006

Nitrate uptake and in vivo, nitrate reductase activity (NRA) in roots of Phaseolus vulgaris, L. cv. Witte Krombek were measured in nitrogen‐depleted plants of varying sugar status, Variation in sugar status was achieved at the start of nitrate nutrition by excision, ringing, darkness or administration of sugars to the root medium.The shape of the apparent induction pattern of nitrate uptake was not influenced by the sugar status of the absorbing tissue. When measured after 6 h of nitrate nutrition (0.1 mol m−3), steady state nitrate uptake and root NRA were in the order intact>dark>ringed>excised. Exogenous sucrose restored NRA in excised roots to the level of intact plants. The nitrate uptake rate of excised roots, however, was not fully restored by sucrose (0.03–300 mol m−3).When plants were decapitated after an 18 h NO3− pretreatment, the net uptake rate declined gradually to become negative after three hours. This decline was slowed down by exogenous fructose, whilst glucose rapidly (sometimes within 5 min) stimulated NG−3 uptake. Presumably due to a difference in NO3− due to a difference in NO3− uptake, the NRA of excised roots was also higher in the presence of glucose than in the presence of fructose after 6 h of nitrate nutrition. The sugar‐stimulation of, oxygen consumption as well as the release of 14CO2 from freshly absorbed (U‐14C) sugar was the same for glucose and fructose. Therefore, we propose a glucose‐specific effect on NO3− uptake that is due to the presence of glucose rather than to its utilization in root respiration. A differential glucose‐fructose effect on nitrate reductase activity independent of the effect on NO3− uptake was not indicated.A constant level of NRA occurred in roots of NO3− induced plants. Removal of nutrient nitrate from these plants caused an exponential NRA decay with an approximate half‐life of 12 h in intact plants and 5.5 h in excised roots. The latter value was also found in roots that were excised in the presence of nitrate, indicating that the sugar status primarily determines the apparent rate of nitrate reductase decay in excised roots.
Effects of supplemental UV‐B radiation on growth and leaf photosynthetic reactions of soybean (Glycine max)
Authors: Vu C. V. , Allen L. H. , Garrard L. A. 
Published: April 2006

Experiments were conducted under greenhouse conditions to investigate the effects of enhanced UV‐B radiation (280 to 320 nm) on height, fresh and dry weights, leaf chlorophyll and carotenoids, CO2 uptake rates, and Hill activity in soybean (Glycine max L. cv. Bragg). Plants were exposed for 6 h continuously from midmorning to midafternoon each day to UV‐B radiation which was provided by Westinghouse FS‐40 sun lamps filtered with 0.127‐mm cellulose acetate film (UV‐B enhanced) or 0.127‐mm Mylar S film (UV‐B Mylar control). Three different UV‐B enhanced radiation levels were tested: 1.09 (treatment T1), 1.36 (treatment T2), and 1.83 (treatment T3) UV‐B sun equivalent units (UV‐Bsec) where 1 UV‐Bsec= 15.98 mW·m−2 of solar UV‐B obtained by applying EXP ‐[(α‐265)/21]2, a weighting function that simulates the DNA absorption spectrum, to the UV‐B lamp systems. These UV‐B levels correspond to a calculated decrease in stratospheric ozone content of 6%, 21%, and 36% for treatment T1, T2, and T3, respectively.Daily exposure of soybean plants to UV‐B radiation significantly decreased height, fresh and dry weights, leaf chlorophyll and carotenoid contents, and CO2 uptake rates. Leaf pigment extracted in 80% acetone from UV‐B‐treated soybean plants showed considerable increase in absorption in the wavelength region of 330 to 400 nm with increased UV‐B radiation levels. Chloroplast preparations from leaves of T2 and T3 plants showed significant reductions in Hill reaction measurements.
Distribution and metabolism of root‐applied cytokinins in Pisum sativum
Authors: Morris David A. 
Published: April 2006

When N6 [8–14C] furfuryladenine was applied to the intact root system of Pisum sativum L. cv. Meteor seedlings it was almost completely metabolised to other compounds within 24 h. Of the total activity recovered from the plants 94.5% was retained in the root system itself. 14C was recovered in a number of ethanol‐soluble compounds and in ribonucleic acid, deoxyribonucleic acid and protein fractions of roots, stems, leaves and axillary buds. In rapidly growing axillary buds released from apical dominance by removal of the shoot apex the combined nucleic acid fractions accounted for 63.3% of the total 14C recovered from these organs. Xylem exudate collected from decapitated plants 0 to 12 h after supplying N5[8–14C]furfuryladenine to the roots consistently contained a single major 14C‐labelled compound which, in three different solvent systems, had the same Rf values as a major endogenous cytokinin isolated from the xylem of unlabelled plants. The content of N6 [8–14C] furfuryladenine itself in the xylem exudate was always low and in some experiments it could not be detected.It is suggested that part of the label from N6 [8‐ 14CJfurfuryladenine taken up by the intact root system may have become incorporated in an endogenous cylokinin before export to the shoot.
Differential effects of benzyladenine and potassium on DNA, RNA, protein and chlorophyll contents and on expansion growth of detached cucumber cotyledons in the dark and light
Authors: Haru Kunimaro , Naito Kunihiko , Suzuki Hiroshi 
Published: April 2006

Benzyladenine (BA) and KCl were applied to detached cucumber (Cucumis sativus L. cv. Ohio) cotyledons in continuous light or in the dark with subsequent light. BA brought about an increase in fresh weight and in DNA, RNA and carotenoid contents in both treatments. KCl did not cause an increase in fresh weight and cellular constituents in the dark, but it did result in an increased fresh weight and DNA content after illumination or in continuous light. BA + KCl treatment resulted in increased carotenoid and DNA contents in the dark, and in increases in fresh weight and all cellular constituents upon subsequent exposure to light. The effects of BA and BA + KCl on growth and chlorophyll synthesis decreased with cotyledon age.BA pretreatment in the dark eliminated the lag phase in chlorophyll synthesis and increased the rate of synthesis. Treatment in continuous light had little effect. KCl did not shorten the lag phase in chlorophyll synthesis, but it stimulated the rate of synthesis in the light. Dark pretreatment with BA + KCl markedly increased the effect of BA on chlorophyll synthesis. Chlorophyll content and fresh weight were higher in cotyledons treated with BA followed by KCl than in cotyledons treated in the reverse order. These results suggest that growth and greening in cucumber cotyledons are primarily controlled by BA and that KCl intensifies the BA effect after irradiation.
Biochemical changes during germination and seedling growth in Cuscuta campestris
Authors: Charles Denys J. , Singh Madhav , Sanwal G. G. 
Published: April 2006

Changes in the contents of starch, protein, DNA, RNA, total phosphorus, acid soluble phosphorus and inorganic phosphorus, and in the activities of some enzymes of carbohydrate, amino acid, nucleic acid and phosphate metabolism were studied during the germination of Cuscuta campestris seeds. The results are expressed on per seed basis.Starch content in Cuscuta seeds showed a steady decline with most of it depleted by the end of the eighth day of germination. Protein content increased with germination up to 48 h and then decreased. RNA and DNA contents increased to a maximal level on the fourth day of germination and then decreased. Total phosphorus in the seeds remained almost unchanged during the period of study. Both trichloroacetic acid soluble and inorganic phosphorus increased until the third day and then decreased. Phytin was rapidly hydrolyzed with little being detectable by the seventh day of germination. Glucose‐6‐phosphate dehydrogenase increased with germination, while fructose bisphosphate aldolase which is indispensable for glycolysis, decreased with germination. Ribonuclease and deoxyribonuclease increased till the third and fourth day, respectively, and then decreased. Aspartate and alanine aminotransferases showed a maximum on the second day and then decreased. Activities of alkaline fructose‐1,6‐bisphosphatase and phytase were absent in the dry seeds and appeared only on the second day of germination. Both α‐ and β‐amylase activities were present in the dry seed.
Catalase activity and isozyme pattern of the metalloenzyme system, superoxide dismutase, as a function of leaf development during growth of Pisum sativum L. plants
Authors: Lastra O. , Gómez M. , López‐Gorgé J. , del Rio L. A. 
Published: April 2006

The catalase activity and the isozyme pattern of the metalloenzyme system superoxide dismutase (SOD) have been determined in pea (Pisum sativum L., cv, Lincoln) leaves of different ages (apical, middle and lower), during several stages of plant development. Pea seedlings were grown in full nutrient solution in a phytotron. Catalase activity was determined polarographically, and superoxide dismutase isozymes (Mn‐SOD, Cu, Zn‐SOD I and Cu, Zn‐SOD II) were separated by acrylamide gel electrophoresis and their relative amounts quantified by densitonietry. The results indicate that the relative amounts of SOD isozymes are slightly different in leaves of different ages during plant growth and, interestingly, each molecular form of SOD shows a clearly distinct pattern during plant development. These changes in the relative percentages of SOD isozymes could be due to the induction of the distinct molecular forms of SOD by the metals Mn, Cu and Zn, translocated to the different leaves as a result of plant development. The relative percentage of the Mn‐SOD isozyme showed a similar pattern to that of catalase activity, suggesting a possible link between these two metalloenzymes at subcellular level, both cooperating to remove the toxic effects of O‐2 and H2O2.An additional conclusion is that before a certain metalloenzyme can be used as a marker to assess the plant micronutrient status, it is essential to have a detalled study of its activity pattern in leaves of different age during plant development.
The relationship between photosynthetic electron transport and photorespiratory 14CO2 release after DCMU treatment in the duckweed, Lemna gibba
Authors: Chaturvedi Rekha , Haugstad May K. , Nilsen Stein 
Published: April 2006

The photosynthetic rate of Lemna gibba was measured as 14CO2 uptake at the beginning of and after 1 h DCMU treatment during the separate excitation of PS I (703 nm), mainly PS II (662 nm) and the combined excitation of both photosystems (662 + 703 nm) in 2 and 21% oxygen. The results show the Warburg effect. Photosynthesis was significantly reduced by DCMU whenever PS II was excited, at 662 nm and 662 + 703 nm. Photosynthetic enhancement was greater in 21 than in 2% oxygen in both the treated and untreated plants.Photorespiratory 14CO2 release was only affected by DCMU treatment at 662 + 703 nm. It was significantly decreased in 21% O2 and significantly increased in 2% O2 as compared to the controls without DCMU. The 14C‐glycolate remaining in the plant after photosynthesis/photorespiration measurements was reduced whenever the electron supply to PS I was low.These data support the hypothesis that a relationship exists between glycolate metabolism and photosynthesis via the electron transport chain where electrons from the oxidation of glycolate are donated to PS I when the electron supply from water is low.
Energy metabolism of Plantago lanceolata, as affected by change in root temperature
Authors: Smakman Gerard , Rinie (J. J.) Hofstra 
Published: April 2006

The long and short term metabolic effects of a shift in root temperature was investigated in Plantago lanceolata L. with special reference to the role of the cyanide resistant alternative pathway in root respiration. After a 10‐day period of growth at a 13°C root temperature, a decrease in root as well as shoot growth was observed, compared to control plants grown continuously at 21°C. Apart from an increase in shoot soluble and insoluble sugar level, no changes in metabolism were found, neither in root respiration, shoot photosynthesis, nor in root sugar and plant protein level.Decreasing the root temperature from 21 to 13°C gave several clear short term changes in metabolism. Within one hour a decrease in cytochrome chain activity of the roots was found together with an increase in activity of the alternative chain. After 24 h a recovery to the initial level of both chains was observed. An increase in root temperature from 13 to 21°C gave an immediate increase in activity of both respiratory chains that was still present 24 h after the switch.It is concluded that the activity of the alternative respiratory pathway in the root is strongly affected by a sudden temperature change in the root environment. This pathway acts in a way which is described by ‘the energy overflow model'. The presence of the alternative electron transport pathway should be taken into account in determinations of the respiratory Q10. Moreover, the length of time between the temperature change and respiration measurements is an important factor.