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Showing papers in "Plant Physiology in 1949"


Journal ArticleDOI
TL;DR: Evidence that a copper enzyme, polyphenoloxidase (otherwise known as tyrosinase or catecholase), is localized in the chloroplasts of spinach beet (chard), Beta vu?garis is presented.
Abstract: The chloroplast, as the seat of chlorophyll pigments in plants, occupies a unique position in the economy of the green cell. In recent years there has been a renewed interest in the reactions and properties of chloroplasts as a result of the work of Hill (11, 12) and Hill and Scarisbrick (13, 14) who demonstrated that the reaction characteristic of photosynthesis in green plants, the evolution of oxygen, occurs in appreciable quantities in isolated chloroplasts under the influence of light and in the presence of suitable oxidants (2, 7, 8, 26). In the course of an investigation of oxygen evolution by isolated chloroplasts it was deemed important to explore their enzymatic composition. Of special interest were considered enzymes capable of participating in oxidation-reduction reactions, and more particularly, those localized principally, if not entirely, in the chloroplasts. This paper presents evidence that a copper enzyme, polyphenoloxidase (otherwise known as tyrosinase or catecholase), is localized in the chloroplasts of spinach beet (chard), Beta vu?garis.

20,139 citations


Journal ArticleDOI
TL;DR: The purpose of the investigations here described was to determine to what extent the chemical composition of a plant can be altered by growing it under different environmental conditions.
Abstract: The purpose of the investigations here described was to determine to what extent the chemical composition of a plant can be altered by growing it under different environmental conditions. The three general processes which determine the organic composition of a plant are photosynthesis, respiration, including aerobic and anaerobic catabolism, and biosynthesis. In the present state of knowledge it is difficult to discern to what extent these three processes are interrelated. For the immediate purposes of this investigation it is, in fact, not essential to attempt to determine which of these processes may be responsible for any observed changes in composition. If decided changes in composition are observable as results of altered environmental conditions, these effects can then be further analyzed and can perhaps ultimately be ascribed to one or another of the major processes. The immediate problem was to discover which environmental conditions would, when altered, affect the organic composition of the plant, and to determine the nature and magnitude of the effect. The objective was to find environmental conditions which would materially modify the relative proportions of the three major plant constituents, carbohydrates, proteins and lipids. For such an undertaking, very little information was available as a basis for a working hypothesis to aid in the choice of environmental conditions. It was obvious from the outset, therefore, that a large number of experiments would have to be made. In an investigation requiring many analyses, the determination of the organic composition of the plants in terms of definite chemical compounds, or even of groups of compounds, would be very laborious and time consuming. Regarding all of the organic carbon of the plant as arising from the reduction of, carbon dioxide, we were more concerned with the energy level of this total organic matter than with the isolation of particular constituents. The determination of the heat of combustion of the plant material would, in a measure, satisfy this requirement; but such data would have a limited usefulness. Recourse was taken to a very simple means of determining the "degree of reduction" of the entire organic material of the plant from its elementary chemical composition. This general concept, which has been used but little in connection with problems of this nature,

399 citations


Journal ArticleDOI
TL;DR: Use of the tetrazolium method merely involves preparation of the embryo of various species of seeds in such a way that all those parts which are decisive in the estimation of germinability be made visible.
Abstract: In 1942 the author published the so-called tetrazolium method for determination of the germinability of seeds (3). This method is based upon the reduction in germinability of the seeds due to a gradual dying-off of the embryo (2). The topographical spread of necrosis of embryo tissues can be demonstrated by means of 2,3,5-triphenyl-tetrazolium-chloride. This compound is colorless but is reduced (hydrated) into the stable but nondiffusible red formazan by living cells (3). Coloration of a cell by tetrazolium is a definite indication of its viability because necrotic cells remain uncolored. By means of extensive experiments conducted over a period of years, the procedure has been perfected to demonstrate which parts of the embryo are at least sufficiently viable to make germination possible (4). The recent publication of R. H. Porter, Mary Durrell, and H. J. Romm (1) concerning the topographical tetrazolium method does not, however, present the method correctly in relation to several essential points. In order to correct these errors, the present author submits a short description of his method (3). Use of the tetrazolium method merely involves preparation of the embryo of various species of seeds in such a way that all those parts which are decisive in the estimation of germinability be made visible. In most cereals the anterior face of the embryo must be visible. Since the pericarp is impermeable and opaque in most cereals, the embryo must be removed from the kernel with a lance-like scalpel or dissecting needle. Except in maize, a longitudinal section through the center of the embryo is not adequate because the lateral root primordia remain invisible. Only in oats is the pericarp sufficiently transparent to obviate excision of the embryo. The embryo of maize, however, possesses a simple root primordium, and the lateral root primordia (secondary radicles) in the mesocotyl are uniformly distributed. In this instance a longitudinal section provides the best preparation (5). The presoaking of the seeds in water is necessary only to facilitate the removal of the embryo. Initiation of germination is neither necessary nor significant for the test because even non-after-ripened cereals can reduce tetrazolium According to the method described below, the cross-sectioned grains of oats are placed in tetrazolium solution without pre-soaking. Only in the case of maize is the staining of the scutellum important in relation to germinability. This response of

213 citations



Journal ArticleDOI
TL;DR: The experiments with Kentucky bluegrass were conducted primarily for the purposes of studying the physiological response of this species to management practices which might influence forage and seed production, and the formation of flowers in May and June has placed this species in the "long-day'' class.
Abstract: The responses of plants to varying photoperiod has received much attention since Garner and Allard (3, 4) first showed that flowering and fruiting of many plants is controlled by the relative length of day and night. Numerous species have been classified as "short day" or "long day" on the basis of the day length required for maximum flowering and fruiting. Temperature also may influence the flowering responses of plants (13), and the two factors may show interaction (11). The experiments with Kentucky bluegrass (Poa pratensis L.) reported here were conducted primarily for the purposes of studying the physiological response of this species to management practices which might influence forage and seed production (9t 10). The formation of flowers in May and June has placed this species in the "long-day'' class. However, Evans and Watkins (2) found that bluegrass plants produced inflorescenses in the spring regardless of length of day, and none was reported in the fall under day lengths ranging from 8.5 to 18 hours. Since plants are dependent upon their leaves for both the stimulus of photoperiod (5, ?) and reserve accumulations, any cultural treatments such as close grazing or clipping of Kentucky bluegrass could influence subsequent seed production, either through induction or through subsequent development of flowers and fruits. An interaction of nitrogen fertilization with photoperiod also was found in studies reported by Borthwick (1).

60 citations


Journal ArticleDOI
TL;DR: This study was made to determine the similarity of the effects of several organic compounds and the plant auxin, indoleacetic acid, on the straight growth of Avena coleoptile sections.
Abstract: A large and diverse group of organic compounds is reported to "regulate" plant growth. Many of the determinations of growth regulation, however, do not measure the accelerating effects on growth but the inhibition of growth or toxicity effects. Such evidence does not suffice to identify the substances as growth regulators which may either accelerate or inhibit the growth process depending upon their concentration. Many techniques exist for the quantitative determination of the acceleration of plant growth by organic compounds (4, 9, 10, 11, 16, 17,). Of these the straight growth of Avena coleoptile sections has distinct advantages. This test gives quantitative data on growth response, it enables the study of accessory factors involved in the growth process, it is sensitive to the effects of substances which do not cause an Avena curvature response, and it does not depend on the complicated series of reactions of the pea test. This study was made to determine the similarity of the effects of several organic compounds and the plant auxin, indoleacetic acid (20), on the straight growth of Avena coleoptile sections. Most of the compounds have been studied by other investigators but their results cannot be correlated satisfactorily because of the different techniques employed in the measurement of the growth effects.

59 citations


Journal ArticleDOI
TL;DR: The object of the present work was to find how closely the dye-reducing system of isolated chloroplasts is related to photosynthesis, by comparing the response of the former to various poisons and narcotics whose action upon the latter is already known, and to investigate the nature of the chloroplast apparatus through its activity.
Abstract: Physiological research directed upon the activity of isolated chloroplasts has been spurred by the belief that the photochemical activity which chloroplasts exhibit in vitro is part of photosynthesis. If this is so, then those components of the photosynthetic apparatus which are active in isolated chloroplasts can thus be brought into closer range for study. The object of the present work was to find how closely the dye-reducing system of isolated chloroplasts is related to photosynthesis, by comparing the response of the former to various poisons and narcotics whose action upon the latter is already known, and to investigate the nature of the chloroplast apparatus through its activity. It is believed that the photochemical and enzymatic machinery of that part of the photosynthetic mechanism which brings about the oxidation of water and the liberation of oxygen can be removed from the living cell intact in the chloroplast structure in a form such that it will continue to function in vitro in the presence of externally supplied oxidants. It was the presence of such oxidants in aqueous leaf extracts which permitted the action of freed chloroplasts in Hill's initial experiments (7) wherein the evolution of oxygen was followed spectrophotometrically via the conversion of haemoglobin to oxyhaemoglobin. Such oxidants must also have been important in the original experiments by Haberlandt (6) and Ewart (3), and in those investigations by Molisch (16, 17) and Inman (13, 14) which followed. Hill (8)found that ferric potassium oxalate may be substituted for these unknown oxidants, and more recently Warburg and L?ttgens (20) struck a close analogy to photosynthesis through the successful use of pbenzoquinone which accepts hydrogen in its reduction, unlike Fe+++ in the Hill reaction but like anabolites in photosynthesis. Holt and French (10) found that chromate and ferricyanide can be reduced by the action of isolated chloroplasts with the evolution of oxygen, and developed a technique involving the visible reduction to their leucoforms of several redox indicators (referred to here as "dyes"). The reduction of such dyes is now followed photometrically by the employment of a photronic cell, with appropriate filters, connected to a galvanometer. This method was used in the poisoning studies reported below and will be described in more detail in a forthcoming paper by Holt, Smith and French (12). ? Present address : Carnegie Institution of Washington, Division of Plant Biology, Stanford, California.

52 citations



Journal ArticleDOI
TL;DR: Chemical analyses for amino acids, ether extract, carbohydrates, ash and crude fiber are presented for the stems of untreated red kidney bean plants and for those treated with 2, 4-D.
Abstract: It has been shown (2, 5, 8, 11) that treatment of plants with 2, 4-D results in a reduction in carbohydrate content and an accumulation of nitrogen. Investigators (4, 6,) have reported that some plants sprayed with solutions of 2, 4-D develop enlarged and proliferated tissues, noted primarily in the stems. It has also been observed that some plants which were sprayed with 2, 4-D and which developed proliferated tissue of this type were eaten more readily by animals (7). Since little is known about the chemical composition of this abnormal tissue, the work reported in this paper was projected to include the analysis for amino acids, ether extract, carbohydrates, ash and crude fiber. Results of chemical analyses are presented for the stems of untreated red kidney bean plants and for those treated with 2, 4-D.

49 citations


Journal ArticleDOI
TL;DR: Ether extraction has been used extensively in correlation studies, particularly since ether was considered to remove the free auxin, however, it soon became evident that auxin was liberated during the extraction and that many months of successive ether extractions were required before auxin production disappeared.
Abstract: Auxin physiologists often have attempted to establish correlations between the amount of auxin in a plant tissue and the manifestation of auxin activity such as growth, rooting, parthenocarpy, bud inhibition, etc. With Avena coleoptiles and tomato stem tips, to use specific examples, it is possible to demonstrate a correlation between growth and the amount of auxin which can be diffused from the tissue into agar. Many tissues produce too little diffusible auxin or are too cumbersome to lend themselves to this type of auxin analysis and resort must be made to more convenient methods of auxin extraction. Ether extraction has been used extensively in correlation studies, particularly since ether was considered to remove the free auxin. It soon became evident, however, that auxin was liberated during the extraction and that many months of successive ether extractions were required before auxin production disappeared. While there often appeared to be a correlation between the amount of auxin obtained in the first ether ex-

48 citations



Journal ArticleDOI
TL;DR: The observations supported the hypothesis of Bennet-Clark that certain of the polysaccharides and the malic acid in succulent plants of this type are the respective beginning and end products of a series of chemical equilibria, the relative concentration of these components at any point of time being a function of the conditions of illumination to which the leaves had previously been exposed.
Abstract: It has been shown in a previous paper (7) that the diurnal variation of the organic acid content of excised leaves of Bryophyllum calycinum cultured in water under normal light conditions in the greenhouse is accompanied by a diurnal variation of the starch content in the opposite sense. The acidity decreased during the day while the starch increased, but the acidity increased during the night while the starch decreased. In terms of the quantity of organic substances concerned, these two changes in composition were by far the largest observed, and their relative magnitude was such as to lend color to the view that the metabolism of organic acids in the leaves is closely connected with that of starch. The observations thus supported the hypothesis of Bennet-Clark (1, 2) that certain of the polysaccharides and the malic acid in succulent plants of this type are the respective beginning and end products of a series of chemical equilibria, the relative concentration of these components at any point of time being a function of the conditions of illumination to which the leaves had previously been exposed. The observations of Wolf (12, 13) have laid particular emphasis upon starch as the polysaccharide concerned in the case of Bryophyllum calycinum. The previous experiment carried out in this laboratory was limited to a study of the changes in composition of samples of Bryophyllum calycinum leaves cultured in water over a period of 24 hours. It seemed desirable, therefore, to repeat the experiment and study the changes for a longer period in order to see to what extent the chemical transformations would continue to respond to repeated alternations of light and darkness. Furthermore, a moderately accurate analytical method for isocitric acid has since become available, and direct examination of the behavior of this component is now possible. In the previous work, isocitric acid had been estimated by difference, a procedure that might well introduce error into the conclusions reached.


Journal ArticleDOI
TL;DR: The present report concerns the relationship of temperature to the composition of ryegrass after cutting, which verified the fact that soluble carbohydrates and starch function as reserves and showed a typical U-shaped curve.
Abstract: In a previous paper (12) it was reported that, when perennial ryegrass (Olium perennjj .) was partly defoliated, the remaining plant parts underwent a progressive loss in soluble carbohydrates, namely sugars and fructosan, for a period of several weeks. This loss from the stubble and roots accompanied a rapid formation of new tissue above ground. When new top growth had produced sufficient photosynthetic area to manufacture its own organic matter, storage of soluble carbohydrates took place. When the percentages of the constituents were plotted against time as the abscissa, the soluble carbohydrates displayed a typical U-shaped curve. Many factors undoubtedly influence the slope and extent of this curve and some of these are being investigated. The present report concerns the relationship of temperature to the composition of ryegrass after cutting. The earlier paper included a review of the literature pertinent to the subject of reserves. Since then, other reports concerned with the analyses of forage grasses have verified the fact that soluble carbohydrates and starch function as reserves. More complex carbohydrates and those more resistant to hydrolysis, are not so regarded. Some of these recent papers are by BENEDICT and BROWN (2), PHILLIPS and SMITH (9), MCILVANIE (8), WEINMANN and REINHOLD (18), and WEINMANN (13, 14, 15, 16). A review by Weinmann covers the general subject of reserves in grasses (17). Reserves in grasses are closely connected with the resistance of the plants to high temperatures. JULANDER (6) showed that grasses withstood limited exposures to a temperature of 480 C (118.40 F) when they had been previously hardened to dry conditions and had not been severely clipped. Both of these last conditions were conducive to the accumulation of reserve carbohydrates. He also noted differences between species, Kentucky bluegrass dying sooner at this temperature than Bermuda grass and a number of range grasses. At lower temperatures, grasses will survive for longer periods. According to HARRISON (5), Kentucky bluegrass grew very little at a constant temperature of 1000 F after having been defoliated, and died

Journal ArticleDOI
TL;DR: Staining methods involving the reduction of selenium salts or of tetrazolium compounds to colored forms by the action of living cells seem to be the most promising quick tests of viability for estimating viability in seeds.
Abstract: Rapid methods for estimating viability in seeds have been suggested by a number of workers. Most of these are dependent upon the increased permeability (6, 10) or decreased reducing power (5, 8) of dead cells or tissues. Staining methods involving the reduction of selenium salts (4) or of tetrazolium compounds (9, 11) to colored forms by the action of living cells seem to be the most promising quick tests of viability. These tests should be particularly applicable to estimations of freezing injury in seed corn because: (a) corn is easily tested (11), (b) immature corn shows a degree of dormancy (13) which makes routine laboratory tests of germinability difficult and slow, and (c) speed is always essential to determine whether frozen seed corn is sufficiently viable to justify expensive processing, or whether the crop should be diverted to other uses.

Journal ArticleDOI
TL;DR: In studies on the algae remarkably little attention has been paid to those details of metabolism which have proved essential in understanding the physiology of other microbial forms, on the carbon and nitrogen balance, for instance, there is little available information.
Abstract: In studies on the algae remarkably little attention has been paid to those details of metabolism which have proved essential in understanding the physiology of other microbial forms. On the carbon and nitrogen balance, for instance, there is little available information. Krogh, Lange, and Smith (3) obtained a carbon balance on a culture of Scenedesmus which showed that 95% of the carbon was retained by the cells under the usual conditions of algal culture. Barker (1) made tests for but failed to find soluble photosynthate which might be excreted by diatoms. One report of excreted photosynthate is that of Uhvtts (11) who found that very small amounts of acetaldehyde of the order of 10e to IO5 moles could be obtained from 200 to 700 ml. of algal suspension (C. pyrenoidosa) when bisulfite had been added to the medium. It is also common observation that algal cultures develop small amounts of bacterial growth even in completely inorganic media. More complete information on the carbon and nitrogen balance is needed.

Journal ArticleDOI
TL;DR: A Q1o smaller than 1 was contrary to the accepted view, that at low temperatures sugar translocation decreases, and appeared to be intermediate between the values found for low temperature and values for higher temperatures of 17-24° C.
Abstract: One of the most controversial problems in plant physiology is that of translocation of organic materials inside the plant. This is mainly due to a lack of information. In spite of the investigations of Crafts, Curtis, Mason, Munch, Phyllis, Schumacher and many others, we need much more basic information before we will have a proper insight in this problem and before we can accept a satisfactory theory of translocation. The recent work of WENT (17) had stressed the importance of the process of sugar translocation at higher temperatures, since this seemed to be the limiting process in the growth and development of tomato plants. Furthermore, it had been concluded on the basis of three different lines of experimental approach, that the Q10 of sugar transport was less than 1 in the tomato plant. In subsequent work more evidence was collected for the low Q1o of sugar translocation, not only in the tomato plant (WENT 18, WENT and ENGELSBERG 21, WENT and CARTER 20), but also in the chili pepper (DORLAND and WENT 7). A Q1o smaller than 1 was contrary to the accepted view, that at low temperatures sugar translocation decreases. This view was based on the work of several investigators. CHILD and BELLAMY (2) had observed a greatly increased outgrowth of adventitious buds on the leaves of Bryophyllum when their petioles were chilled to 2.5 4 C for a few days. This seemed to indicate a greater concentration of carbohydrate in the leaves with chilled petioles, but no direct sugar determinations were carried out to support this interpretation. Therefore the results might as well be interpreted as an increased rate of movement of other bud growth factors towards the leaves. CURTIS (4) and CURTIS and HERTY (5) studied the effect of temperature of the petiole on the loss in darkness of dry material from the primary leaves of the red kidney bean (Phaseolus vulgaris L.) It was found that cooling the petioles to 0.5-4.5' C greatly retarded translocation of carbohydrates from the leaf blades. However, if the treatment was continued for 17-20 hours, a significant amount of transport took place. Sugar transport was also retarded when the entire plant was kept at temperatures of 0-2° C. At intermediate temperatures of 7-11° C sugar translocation appeared to be intermediate between the values found for low temperature and values for higher temperatures of 17-24° C. Chilling of the main stem just below the first pair of leaves for two days to a temperature of 2-5° C clearly showed that the upward movement of

Journal ArticleDOI
TL;DR: The present investigation is an attempt to further knowledge ofChemotropism of pollen tubes to pistil parts and the role that chemotropism plays in directing the pollen tubes toward the egg.
Abstract: Although much has been added to our knowledge concerning the requirements for pollen germination and pollen tube growth in recent years (1, 2, 4, 10, 17, 18), very little progress has been made in studying chemotropism of pollen tubes. Literature dealing with this subject prior to 1924 has been reviewed by Brink (3). There is an obvious lack of agreement among the different workers as to: (a) whether chemotropism of pollen tubes to pistil parts exists at all; and (b) if so, the role that chemotropism plays in directing the pollen tubes toward the egg. The present investigation is an attempt to further our knowledge of this process.


Journal ArticleDOI
Sally Kelly1
TL;DR: Akamine's recent experiments indicate that root induction by 2,4-D is influenced by temperature, and the following experiments were carried out to investigate more precisely the relationship between temperature and susceptibility of plants to 2, 4-D.
Abstract: The conditions under which 2,4-D is most effective as a weed-killer are not thoroughly established. Among the possible factors influencing the result of 2,4-D application is the temperature at which the plants are growing. Hamner and Tukey (2) noticed that killing of bindweed by 2,4-D was more rapid in midsummer than in the fall. Marth and Davis (3) found that 2,4-D killed lawn weeds at a more rapid rate when they were growing at warmer temperatures. Both the absorption and translocation of 2,4-D in bean plants were speeded when they were kept at higher temperatures (4). Akamine's recent experiments indicate that root induction by 2,4-D is influenced by temperature (1). The following experiments were carried out to investigate more precisely the relationship between temperature and susceptibility of plants to 2,4-D.


Journal ArticleDOI
TL;DR: Chlorella oxidative assimilation has been studied in resting cell preparations obtained as a result of starvation, i.e., aerobic incubation in the dark in the absence of organic nutrients.
Abstract: Chlorella has been widely used in studies on photosynthesis with but little attention to possible variations in its metabolic activities. The metabolism of other microorganisms has proved to be quite variable and dependent upon previous history as well as upon prevailing environmental conditions. It has been common practice, for instance, to study resting cells as opposed to actively proliferating cells. Resting cells have been variously obtained by removal of the nitrogen source from the nutrient medium, by washing the cells, or starving the cells of organic nutrients for a period of time. Assimilation of carbon may be much more efficient in resting cells than in growing cells (cf. 10) and for that reason the former have most frequently been used in studies on oxidative assimilation. In Chlorella oxidative assimilation has been studied in resting cell preparations obtained as a result of starvation, i.e., aerobic incubation in the dark in the absence of organic nutrients (6). As a background for the larger problem of assimilation in Chlorella it becomes important to investigate the changes that take place during starvation.




Journal ArticleDOI
TL;DR: The term "negative exudation" will be used to refer to this reverse flow of water through the cut stump into the root system, to avoid the confusion which may arise if such uptake of water is referred to as "absorption'' by theroot system.
Abstract: The intake of water through the freshly cut end of the stumps of previously wilted detopped plants has received little study. The term "negative exudation" will be used to refer to this reverse flow of water through the cut stump into the root system. This terminology used by McDermott (10) appears to avoid the confusion which may arise if such uptake of water is referred to as "absorption'' by the root system. Rosene (12), Eaton (4), and others have investigated the effects of solution concentrations on reversing the movement of water through root systems. Litvinov (9), Crafts and Kennedy (3), Kramer (8), and later McDermott (10) have examined some aspects of the influence of the moisture content of the soil surrounding the roots on water intake by the cut stump of detopped plants. However, no measurements of negative exudation extending over periods of several days have come to the writer's attention.


Journal ArticleDOI
H. C. Yin1, C. N. Sun1
TL;DR: The present report embodies the results of the work on germinating seeds, with Soybean chosen as the main experimental material because of the absence of detectable starch, which interferes with the test, in the dormant seeds and during the first days of germination.
Abstract: The discovery of the enzyme phosphorylase provides an important clue toward the solution of the problem of starch transformation in plants (5). The enzyme has been purified and its properties and reactions in vitro are fairly well understood (7) (11). Only its physiological role in the living plant remains obscure. One approach to this problem is to investigate the distribution of the enzyme in different tissues and cells to correlate it with the site of normal starch synthesis. For this purpose a histochemical method has been devised and described (13). With this method a number of observations have been made on various plant parts. The present report embodies the results of the work on germinating seeds. Briefly the method for the detection of phosphorylase (13) consists of incubating free-hand sections of plant parts in a buffered medium of glucose1-phosphate (prepared according to the method of HANES (6) and of subsequent staining with iodine in potassium iodide. The amount of starch formed is taken as a measure of the phosphorylase activity. Incubation is conducted at 25° C and lasts for a half to one hour, or longer in case the enzymic activity is particularly weak. Soybean was chosen as the main experimental material because of the absence of detectable starch, which interferes with the test, in the dormant seeds and during the first days of germination. Castor bean which is also practically starch-free was also tried. For comparison, broad bean was used, but in this case the embryo was removed from the cotyledons and starved for several days to rid it of stored starch.