Carrot Tissue Research Articles

The Effects of 2,4,6-Trichlorophenoxyacetic Acid on Embryogenesis in Wild Carrot Tissue Cultures

Adventive embryogenesis in wild carrot is enhanced by the lowering of the effective auxin concentration either by removal from the medium or by the addition of 2,4,6-T (2,4,6-trichlorophenoxyacetic acid) or both. Growth is similar in undifferentiated and differentiated tissue until the embryos begin to elongate; the elongation is slower in the presence of 2,4,6-T and a greater homogeneity of developmental stages occurs. Also, root hairs do not form in the presence of 2,4,6-T. Aerobic respiration is stimulated by 2,4,6-T and a synergistic effect with DNP also occurs. In addition, DNP exerts a greater effect on older tissue than on younger tissue.

Phytochrome in Cultured Wild Carrot Tissue

Disappearance and transformation of phytochrome in light-treated, dark-grown cultured tissue of wild carrot (Daucus carota L.) have been analyzed. Evidence is presented for the existence of two populations of far red-absorbing phytochromes: one which is subject to reversion, and a second which undergoes loss of photoreversibility. Phytochrome levels and transformation characteristics have been compared for several strains and developmental stages of cultured wild carrot tissue.

Loss of Electrolytes and Amino Acids from Gamma-Irradiated Carrots

The loss of electrolytes and amino acids from gamma-irradiated carrot tissues to an aqueous medium was found to be both dose and dose-rate dependent. Calcium was the cation most readily leached, fo...

CHANGE OF APPARENT WEIGHT OF PLANT TISSUES IN SOLUTIONS

SummaryThe volume in carrot tissue apparently not penetrated, AOV, by a plasmolysing solution of cane sugar, potassium nitrate, potassium chloride or calcium chloride is a linear function of the reciprocal of the osmotic pressure of the solution over the range of the concentration used. This AOV, which includes the solids in the cell walls, is practically independent of the nature of the electrolytes but appears to be greater for cane sugar. There is no clear evidence for any active transport of water into the vacuoles of the cells.

Effect of adenine nucleotides on levels of glycolytic intermediates during the development of induced respiration in carrot root slices.

Incubation of freshly cut carrot tissue in Na(3)ADP and Na(3)ATP promotes a marked intracellular increase in both ADP and ATP. The rapid increase in ATP during an ADP incubation and in ADP during an ATP incubation results from the activity of cytoplasmic enzyme systems upon the nucleotide absorbed into the cell from the incubation medium. There is a crossover at the pyruvate kinase reaction, but not at phosphofructokinase, when either ADP or ATP is added to freshly cut tissue. In tissue slices washed in distilled water, pyruvate kinase exhibits a negative crossover in the first 2 hours and a positive crossover between 2 and 10 hours after cutting. Cutting induces large changes in levels of nucleotides and glycolytic intermediates. There is an immediate depletion of these compounds upon cutting, so that nucleotides are added to a system where respiration rate is limited by endogenous nucleotide level. Variation in respiratory values for fresh cut tissue can be explained in terms of a range of endogenous ADP levels in different tissue batches. Nucleotide incubation experiments are discussed in relation to the provision of ADP to rate-limiting pyruvate kinase during the first phase in development of the induced respiration.

Phytochrome in Cultured Wild Carrot Tissue. I. Synthesis

Stable levels of P(FR) occur in light-grown suspension cultures of wild carrot. Upon darkening such tissue, P(R) accumulates until the high P(R) level characteristics of dark-grown tissue is reached. Data are compatible with the idea of an equilibrium between processes of synthesis and destruction in tissue grown in the light. Reappearance of phytochrome also follows light-induced pigment destruction in dark-grown tissue. The rate of P(R) appearance is similar in both cases. The rate of disappearance of P(FR), however, is slower in light-grown tissue than in dark-grown tissue.

SURFACE BROWNING OF CARROTS

It was established that oxidative browning was confined to the carrot root surface tissue. Phenolic content was determined in carrot tissue at various depths. The phenolic content was highest in tissue nearest the root surface, and phenol content at various depths paralleled the observed potential browning.Paper chromatographic separation of carrot tissue extracts showed complicated patterns of phenolics and blue-fluorescent compounds. Twelve compounds were separated, four of which discolored when treated with tyrosinase. The compound corresponding to chlorogenic acid was the primary oxidative browning substrate, and that corresponding to L-tyrosine was of secondary prominence.

Morphology of edible plant cells and tissues in vitro

Morphological features were studied of callus tissues from carrot root, endive embryo, lettuce leaf petiole and stem, parsley and spinach leaf petiole, and navy bean and red kidney bean stem grown on solid C- or D-medium. The callus tissue of carrot, endive, lettuce leaf petiole and stem, parsley, and red kidney bean were irregularly lobed while the callus tissues of navy bean and spinach were hemispherical and somewhat flattened, respectively. The cultures of carrot and endive were firm and massive, while the calli of other species were friable. Callus cells of these seven species, examined with the phase microscope, varied in size and shape. The callus cells of carrot, lettuce leaf petiole and stem, navy bean, and red kidney bean were spherical, oval, and elongated. Endive callus tissue consisted of oval and elongated cells and that of parsley consisted of spherical and oval cells, while spinach callus usually consisted of spherical cells. Elongated cells ranged from 204 to 475 μ in length by 45 to 92 μ in width, spherical cells 62.5 to 129.8 μ in diameter, and oval cells 118 to 172.8 μ in length by 63 to 94.5 μ in width. Variations were noted in the morphology and number of cell inclusions including the nucleoli, plastids, mitochondria, and starch granules. In chlorophyllous cells, the chloroplasts were generally scattered in the cytoplasm, but in spinach it often surrounded and obscured the nucleus. Varying numbers of starch granules were seen around the nucleus and in the cytoplasm.

Untersuchungen �ber Beziehungen zwischen der Differenzierung und der Zusammensetzung der l�slichen Proteinfraktion von Gewebekulturen und Bl�ttern von Daucus carota

The correlations between differentiation, the amino acid composition of total protein and of soluble protein, and the disc electrophoretic distribution of soluble protein of carrot tissue cultures and of carrot plants (leaves) were studied. In spite of pronounced and characteristic changes in the electrophoretic distribution of the components of soluble protein in various developmental stages of both bioassays, no significant differences in the amino acid composition of protein were observed. With progressive development of whole carrot plants and of carrot tissue cultures, the number of protein bands on disc electropherogramms increased.

Compartmentation and exchange of chloride in carrot root tissue

1. 1. An attemp has been made to provide an experimental basis for interpreting the kinetics of the exchange of Cl − in excised carrot tissue. 2. 2. The fastest component of the efflux of tracer Cl − from carrot tissue is shown to be extracellular in origin. The two slower components are shown to be subcellular in origin, and are equated with the cytoplasm and the vacuole. 3. 3. When tissue is transferred from salt solution to water, the efflux of tracer Cl − is much reduced. On transfer back to salt, there is an initial burst before the Cl − efflux returns to the original level in salt. The initial burst is shown to represent loss of Cl − from the cytoplasm. This indicates that Cl − can move directly between the cytoplasm and the vacuole, and that the inhibition of Cl − efflux in water is an effect mainly at the plasmalemma. Further quantitative consideration ssuggest that there is no direct connection between the vacuole and the external solution. 4. 4. With the use of a model in which the cytoplasm and vacuole are arranged exclusively in series, the one-way fluxes at the plasmalemma and tonoplast and the cytoplasmic and vacuolar contents are estimated over a range of external Cl − concentrations. In conjuction with electrical measurements, these results show that Cl − is probably actively transported inwards across both plasmalemma and tonoplast, and that there is a 1-for-1 exchange diffusion component of the Cl − fluxes at the plasmalemma. Anions, other than halide are much less effective than Cl − in exchanging for internal 36Cl −.

Investigations on the growth and metabolism of cultured explants of Daucus carota

The effects of Fe, Mo and Mn on the growth of explants drawn from different carrot clones were investigated. The explants were cultured aseptically on purified basal media supplemented with coconut milk. The two components of growth, i.e. cell division and cell enlargement, seem to respond differentially to the trace elements in question. Fe plays the key role and acts as a "trigger" of the action of coconut milk in stimulating cell division. Neither Mo nor Mn could replace iron in this respect. Mo and Mn acting separately tend to foster growth by cell enlargement to a different degree and at different concentrations. However, when Mo and Mn were added together to a medium containing iron, they seem to interact and stimulate growth by cell division and cell, enlargement still further. The suggestion is made that the behavior of the explants from different clones may have been responsive to differences in the functional Fe/Mn ratio which also involves endogenous levels of trace elements as well as the exogenous levels furnished in the medium.Thus, the element Fe emerges as the key trace element which interacts with the factors present in coconut milk to induce growth in the otherwise quiescent carrot tissue.

The Influence of Gamma Radiation on Carbohydrate and Citric Acid Cycle Metabolism in Carrot Tissue

A study of the effect of60 Co γ-radiation on the metabolism of glucose and various organic acids by carrot tissue was conducted. Radiation resulted in the increased absorption of glucose and pyruvate and the decreased absorption of acetate and succinate. Only a slight effect on glucose and pyruvate catabolism was found, but there was an increase in acetate and a decrease in succinate catabolism. Radiation produced a reduction in the anabolic utilization of all substrates. This included a reduced lipid synthesis from acetate and a net accumulation of this substrate within the tissues. The evidence points to the tricarboxylic acid cycle as being the source of radiation-accelerated CO2 evolution. It is postulated that a relatively radiation-resistant bypass system is present in carrots which is capable of circumventing the radiation-depressed succinate utilization. The high-level-radiation degradation products of glucose produced no toxic effects on glucose metabolism.

A multiple unit radiometric respirometer for the measurement of the metabolism of carbon-14 labelled substrates

An improved radiometric respirometer is described which permits periodic sampling of both the envolved C 14O 2 and the activity remaining in the substrate solution, as well as the complete recovery of added radioactivity. The system, although described for use with plant tissue may be used with insects or small animals. A procedure for the use of the system is described, and a typical experiment utilizing irradiated carrot tissue is discussed.

Free Amino Acids in Gamma-Irradiated Carrots

Studies were conducted to determine the effect of60 Co γ-radiation on the radiosensitivity of free amino acids in metabolizing carrot tissue and on the synthesis of free amino acids from specifically labeled acetate. At 100-krad doses, the concentration of some amino acids decreased; at 500 krads, all were depressed; and at 1000 krads, the concentration of all amino acids was severely reduced. With the exception of isoleucine, glycine, valine, and phenylalanine, synthesis from labeled acetate of all amino acids occurred, with glutamate, serine, and aspartate being synthesized in the greatest amounts. In general, γ-radiation reduced synthesis from labeled acetate at all doses above 100 krads and severely inhibited synthesis at 1000 krads. Incorporation of the carboxyl carbon of acetate was generally less extensive and more radiation-reduced than that of the methyl carbon.

High Phytochrome Levels in Cultured Tissue of the Wild Carrot, Daucus carota

High Phytochrome Levels in Cultured Tissue of the Wild Carrot, <i>Daucus carota</i>

Ion uptake by carrot tissue and mitochondria.

It is shown that aged carrot disks which accumulate ions and show salt-stimulated respiration are suitable for the isolation of mitochondria.

Increased Disease Resistance and Enzyme Activity Induced by Ethylene and Ethylene Production of Black Rot Infected Sweet Potato Tissue

Exposure of root tissue from a susceptible variety of sweet potato to low concentrations of ethylene induced a resistance to infection by Ceratocystis fimbriata and an increase in the activity of peroxidase and polyphenoloxidase in the tissue. Susceptible tissue that was inoculated with a pathogenic strain of C. fimbriata or a nonpathogenic strain that can induce resistance liberated more ethylene into closed chambers than tissue inoculated with strains that did not induce resistance. It is suggested that ethylene may be a stimulus that diffuses from infected areas into adjoining tissue to initiate metabolic changes which may lead to disease resistance. Polyphenol oxidase but not peroxidase activity was increased in slices of potato tubers and parsnip roots treated with ethylene. The activity of these enzymes in root tissue of carrot, radish or turnip was not altered by ethylene treatment.

Ethanolamine metabolism in plant tissues.

Ethanolamine is readily metabolized by oat, pea, wheat, apple and carrot tissue preparations. Ethanolamine-1,2 (14)C was incorporated into the lipid fraction, and (14)C activity was distributed in the organic acid, sugar, acid volatile, carbon dioxide and insoluble residue fractions. The distribution varied with the particular tissue. Incorporation into the lipid fraction occurred in tissue homogenates in the absence of ATP by a Ca(++) activated system similar to that reported for animal preparations. The initial step in ethanolamine oxidation involves an amine oxidase. Glycolaldehyde and glyoxylic acid are metabolic intermediates, the former in the conversion of ethanolamine to carbon dioxide. No evidence was obtained for the operation of an ethanolamine transaminase or for the involvement of phosphorylated intermediates in the conversion of ethanolamine to carbon dioxide.

Histology an Organesis in Canot Calus Tissue Cultured in Vitro

The carrot callus tissues are cultured on following three kinds of i. e., standard the and the embryo-forming medium, after subculturing of different periods from isolation. The histological observations of these calli are undertaken by ordinary paraffin method. The friable callus tissues within one year and more after isolation are composed of tissue particles. These tissue particles have its characteristic organization according to nutrient medium. The stock callue tissues cultured on standard medium are composed of tissue particles of surface-growing type, in which parenchyma containing groups of tracheid-like element is covered with growing zone of proliferating cells on surface. While nodular callus tissues cultured on the - standard medium. excluding 2, 4-dichlorophenoxy acetic acid - are constituted from minute tissue particles which are homologus to meristematic nodules of Gautheret. These meristematic nodules unite each other with loose parenchyma on their surfaces and build up larger tissue nodule of several millimeters in diameter. During course of repeated subcultures over three years, gradual chages in components of stock callus tissue are observed. In these changes, following two features are distinctly noticeable; first, degeneration of tissue particle into fragments and second, increase in proportion of giant free cell in cell population of callus tissue. When callus tissue within one year after isolation are cultured on root-forming medium, root primordia differentiate endogeneously from cambial layer located uuder outer loose parenchyma of meristematic nodule. From this observation, significance of organization of tissue particles for differention of roots in carrot tissue is suggested. When callus tissues being until about one year after isolation are cultured on the embryo-forming medium, adventive embryos are found to be generated from few embryonic cells that are clearly distinguished by size and stainability from other kinds of cell. The embryonic cells are always situated either on outermost layer of tissue particles or in free state.

Growth and chlorophyll production in plant callus tissues grown in vitro

Growth, nutrition and chlorophyll development were studied in chlorophyllous callus tissues isolated from the following edible angiospermous plants: carrot root, crown gall of tomato, endive embryo, leaf petiole and stem of lettuce, leaf petiole of parsley, pea stem and rose stem. Growth patterns of these tissues in vitro were sigmoid. Synthetic media produced less growth, in terms of fresh weight increase, than media containing coconut milk, a highly complex and little understood natural substance. MURASHIGE and SKOOG'S synthetic medium proved useful for satisfactory growth and chlorophyll production in a number of tissues. Its usefulness was further increased by additional amounts of copper sulphate, potassium nitrate and monobasic ammonium phosphate. Increased levels of iron and magnesium inhibited growth. Incorporation of yeast extract in the tobacco-high-salts-medium produced the highest amount of growth and chlorophyll formation in endive tissue. Presence of exogenous sucrose was essential for the continued good growth of the above callus tissues in vitro. Highest amount of growth took place either in white light or in the dark. Different tissues had different responses to high or low intensities of light. Endive and carrot tissues produced in vitro were palatable to human taste. Endive tissue was particularly good as it also differentiated many small rosettes of leaves, shoots and had a mild aromatic flavor typical of the endive plants grown in nature.