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Plant Physiology

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Plant Adaptations To Saturated Soils And The Formation Of Hypertrophied Lenticels And Adventitious Roots In Woody Species, Kirk J. Havens, Virginia Institute Of Marine Science, Wetlands Program Feb 1996

Plant Adaptations To Saturated Soils And The Formation Of Hypertrophied Lenticels And Adventitious Roots In Woody Species, Kirk J. Havens, Virginia Institute Of Marine Science, Wetlands Program

Reports

No abstract provided.


Cold Acclimation: A Complex Interaction Of Low Temperature, Light And The Redox State Of Photosystem Ii, Gordon R. Gray Jan 1996

Cold Acclimation: A Complex Interaction Of Low Temperature, Light And The Redox State Of Photosystem Ii, Gordon R. Gray

Digitized Theses

The process of cold acclimation refers to the physiological processes by which cold-tolerant plants such as cereals, when developed at low temperature, acquire freezing tolerance. Photosynthesis provides the energy required for these complex metabolic changes to take place. However, photosynthetic organisms must maintain a balance between energy input as a result of photochemical reactions and energy consumption through intersystem electron transport and the various biochemical reactions of cellular metabolism. Imbalances may be sensed by changes in the redox state of photosystem II (PSII), as this represents the rate-limiting step of photosynthetic electron transport. The redox state of PSII is sensitive ...


Chilling Photoinhibition In Zea Mays L And Zea Diploperennis Iltis, Doebely And Guzman: The Role Of Oxygen And Antioxidants, Kajal Bose Ghoshroy Jan 1995

Chilling Photoinhibition In Zea Mays L And Zea Diploperennis Iltis, Doebely And Guzman: The Role Of Oxygen And Antioxidants, Kajal Bose Ghoshroy

Doctoral Dissertations

Light absorbed by photosynthetic pigments must be distributed either for chemical work, reemitted as fluorescence or safely dissipated as heat. Adverse environmental conditions reduce the dissipation capacity of plants and the excess energy leads to damage to the photosynthetic mechanism, termed photoinhibition. Low, non-freezing temperatures cause such photoinhibition, especially in tropical plants grown in the temperate zone. This damage occurs in the photosystem II and is triggered by highly reactive radicals or reactive forms of dioxygen. Numerous studies point to the involvement of oxygen and antioxidant enzymes and substrates in amelioration of these damages. In C$\sb3$ plants, dioxygen is ...


Photosynthetic Acclimation To Light And Temperature: Excitation Pressure And Redox Sensing, Denis Philip Maxwell Jan 1995

Photosynthetic Acclimation To Light And Temperature: Excitation Pressure And Redox Sensing, Denis Philip Maxwell

Digitized Theses

Photosynthetic acclimation to low temperature has been studied extensively. However, since low temperature causes a preferential decrease in the rates of biochemical as compared to photochemical reactions, some alterations brought about by acclimation to low temperature may be the result of the light-harvesting apparatus absorbing more light energy than can be readily dissipated through photosynthesis. This possibility was investigated by using two species of green algae, Chlorella vulgaris and Dunaliella salina and the techniques of chlorophyll a fluorescence, O{dollar}\sb2{dollar}-evolution, protein electrophoresis and Western blotting, high performance liquid chromatography, RNA blot hybridization, and enzyme and metabolite assays ...


Steady-State Natural Fluorescence, Arnold Francis Theisen Jan 1994

Steady-State Natural Fluorescence, Arnold Francis Theisen

Doctoral Dissertations

This study employed a manifold analytical approach to the application of multiple excitation and emission wavelengths of steady-state natural fluorescence for the detection of stressed and damaged vegetation. This investigator has attempted to answer questions put forth in terms of the following null hypothesis: Natural fluorescence emission, measured in the steady-state from living, attached or freshly excised needles of eastern white pine (Pinus strobus L.) or leaves of common beans (Phaseolus vulgaris L.), cannot be used in the form of complete spectra or in ratios of discrete wavelengths as indicators of stress from abiotic sources such as ozone or cadmium ...


Genetic Engineering Of The Polyamine Biosynthetic Pathway And Somatic Embryogenesis In Carrot (Daucus Carota L), Dhundy Raj Bastola Jan 1994

Genetic Engineering Of The Polyamine Biosynthetic Pathway And Somatic Embryogenesis In Carrot (Daucus Carota L), Dhundy Raj Bastola

Doctoral Dissertations

Ornithine decarboxylase (ODC), arginine decarboxylase (ADC), and S-adenosylmethionine decarboxylase (SAMDC) are three of the key regulatory enzymes involved in the biosynthesis of polyamines (putrescine, spermidine and spermine). To modulate the biosynthesis of putrescine, carrot (Daucus carota L.) cells were transformed with Agrobacterium tumefaciens strains containing 3$\sp\prime$-truncated mouse ornithine decarboxylase (ODC) cDNA under the control of a CaMV 35S promoter. Neomycin phosphotransferase gene linked with nopaline synthase promoter was used to select transformed cell lines on kanamycin. While the non-transformed cells contained no ODC, high levels of ODC activity were observed in the transformed cells. A significant increase ...


Ecological Aspects Of Iron Acquisition In Synechococcus Sp (Cyanophyceae), Steven Wray Wilhelm Jan 1994

Ecological Aspects Of Iron Acquisition In Synechococcus Sp (Cyanophyceae), Steven Wray Wilhelm

Digitized Theses

As primary producers, marine cyanobacteria regulate the biological and biogeochemical cycles of aquatic ecosystems and influence ocean-atmosphere gas exchange. The purposes of this project were to determine if a Synechococcus sp. was capable of utilizing a high-affinity iron transport system during periods of iron-limited growth and if physiological changes due to iron limitation could be identified. Resolution of these factors was achieved by maintaining the cyanobacterium Synechococcus sp. PCC 7002 in continuous culture chemostats over a range of iron availabilities.;Changes in physiology were detected over a range of iron concentrations. Reductions in the levels of photosynthetic pigments were accompanied ...


[Delta]-Aminolevulinic Acid Dehydratase Activity During Tomato Fruit Development And Ripening, Marios Costa Kyriacou Jan 1994

[Delta]-Aminolevulinic Acid Dehydratase Activity During Tomato Fruit Development And Ripening, Marios Costa Kyriacou

Retrospective Theses and Dissertations

No abstract provided.


Light Detection System In Higher Plant Chloroplasts: Pigment Mediated Or Overall Photon Flux Density Related, Soumitra Ghoshroy Jan 1993

Light Detection System In Higher Plant Chloroplasts: Pigment Mediated Or Overall Photon Flux Density Related, Soumitra Ghoshroy

Doctoral Dissertations

Plants adapt to short term changes in irradiance and quality of the light environment by modulating the structure of the thylakoid membranes to make the best use of the available light energy. Shade-acclimated chloroplasts develop more thylakoid surface area as compared to those growing in full sunlight. Conversion of sun-type chloroplasts to shade-types and vice versa on the basis of total thylakoid membrane surface area can occur quickly. However, the response mechanism of chloroplasts to changes in light levels is yet to be understood. This short term light detection mechanism may be mediated by a pigment system other than photosynthetic ...


Strawberry Malformation And The Tarnished Plant Bug, David Thomas Handley Jan 1993

Strawberry Malformation And The Tarnished Plant Bug, David Thomas Handley

Doctoral Dissertations

Experiments were designed to study the malformation of strawberries, Fragaria x ananassa (Duchesne) caused by the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois). In greenhouse experiments, duration of blossom exposure to tarnished plant bug affected the type of malformation observed. Exposure at anthesis for 48 hours was most likely to cause apical seediness, the malformation associated with tarnished plant bug. The number of nonviable achenes per fruit increased with longer feeding durations. Malformation was also affected by blossom stage. Prebloom feeding caused blossom death. Feeding at petal fall or achene separation resulted in malformations, including apical seediness. Feeding at ...


Day And Night Temperature Effects On Soybean (Glycine Max Merr.) Seed Yield, Seed Quality, And Seed Composition, Lance R. Gibson Jan 1992

Day And Night Temperature Effects On Soybean (Glycine Max Merr.) Seed Yield, Seed Quality, And Seed Composition, Lance R. Gibson

Retrospective Theses and Dissertations

No abstract provided.


Biosynthesis And Metabolism Of Dolichol And Polyprenol In The Seeds And Seedlings Of Rye (Secale Cereale L), Robert Thomas Rymerson Jan 1992

Biosynthesis And Metabolism Of Dolichol And Polyprenol In The Seeds And Seedlings Of Rye (Secale Cereale L), Robert Thomas Rymerson

Digitized Theses

The seeds of monocotyledonous plants contain both dolichol, an homologous series of {dollar}\alpha{dollar}-saturated polyisoprenoid alcohols, and polyprenol, and homologous series of {dollar}\alpha{dollar}-unsaturated polyisoprenoid alcohols. Dolichyl phosphate (Dol-P) participates in the N-glycosylation of proteins. The function of polyprenol is unknown. Several possible roles for polyprenol were investigated in rye (Secale cereale L.). Methods for the extraction, separation, analysis, and quantification of polyisoprenoids were developed. Rye embryos contained twice as much polyprenol as dolichol; the ratio of polyprenyl phosphate to dolichyl phosphate was estimated at three to one.;Experiments on the metabolic labelling of polyisoprenoids with ...


Physiological And Biochemical Significance Of Peanut (Arachis Hypogaea L) Peroxidases In Growth, Xiaohong Zheng Jan 1992

Physiological And Biochemical Significance Of Peanut (Arachis Hypogaea L) Peroxidases In Growth, Xiaohong Zheng

Digitized Theses

The molecular structures of peanut peroxidases from the cell suspension culture medium have been well characterized. The aim of present work is to investigate some of the physiological roles of these peroxidases, namely the functions in growth.;Specific polyclonal antibodies against both anionic and cationic peroxidases were produced by affinity chromatography. Immunological assays showed virtually no cross-reactivity between these antibodies and other compounds. The peroxidases from peanut cell suspension culture medium had {dollar}>{dollar}80% immunological homologies with those from cultured cells and hypocotyls as determined by Ouchterlony gel diffusion, western blot and competitive ELISA. Based on these homologies both ...


Expression Of The Murine Ornithine Decarboxylase Gene In Transgenic Nicotiana Tabacum Var Xanthi, Richard Anthony Descenzo Jan 1991

Expression Of The Murine Ornithine Decarboxylase Gene In Transgenic Nicotiana Tabacum Var Xanthi, Richard Anthony Descenzo

Doctoral Dissertations

Ornithine decarboxylase (ODC), arginine decarboxylase (ADC), and S-adenosyl-methionine decarboxylase (SAMDC) are the three key regulatory enzymes for polyamine (putrescine, spermidine, and spermine) biosynthesis. In order to gain more insight into the relationship between polyamine metabolism and other physiological processes, research was undertaken to obtain increased putrescine biosynthesis in tobacco by overexpression of a murine ODC cDNA.

Both a full-length and a truncated murine ODC cDNA were cloned into a binary expression vector containing the Cauliflower Mosaic Virus (CaMV) 35S promoter. Using standard leaf-disc transformation procedures, transgenic tobacco plants containing either the full length or the truncated ODC cDNA were obtained ...


Genetic, Physiological And Anatomical Analyses Of A Wilty Mutant In Tomato (Lycopersicon Esculentum Mill, Cv Large Plum), Karen Elizabeth Rasmussen Jan 1991

Genetic, Physiological And Anatomical Analyses Of A Wilty Mutant In Tomato (Lycopersicon Esculentum Mill, Cv Large Plum), Karen Elizabeth Rasmussen

Doctoral Dissertations

Large Plum', a tomato cultivar carrying a wilty mutation (LP-wilty), was characterized genetically, physiologically, and anatomically. Inheritance, complementation, and mapping studies of LP-wilty were performed. The mutation was found to be inherited as a single dominant gene, distinct from other wilty alleles, and was mapped to the long arm of chromosome six.

Measurements were taken of stomatal conductance, root conductance, shoot water potential, and leaf water potential for 'Large Plum' and normal plants. Results suggest that both stomatal conductance and root conductance rates are reduced in the wilty mutants. In addition, shoot and leaf water potentials are more negative in ...


Characterisation Of The Photosynthetic Responses Of Spring And Winter Wheat To Growth At Cold-Hardening Temperatures, Vaughan M. Hurry Jan 1991

Characterisation Of The Photosynthetic Responses Of Spring And Winter Wheat To Growth At Cold-Hardening Temperatures, Vaughan M. Hurry

Digitized Theses

In vivo room temperature chlorophyll a fluorescence coupled with CO{dollar}\sb2{dollar} and O{dollar}\sb2{dollar} exchange are measured to determine the effect of cold-hardening on the photosynthetic capacity and the susceptibility to photoinhibition of six cultivars of wheat (Triticum aestivum L.), covering a range of freezing tolerance. The role of the photosystem II (PSII) repair cycle in resistance to, and recovery from, photoinhibition is assessed at both low temperatures (5{dollar}\sp\circ{dollar}C & {dollar}-3\sp\circ{dollar}C) and in the presence of the 70S protein synthesis inhibitor, chloramphenicol. The effect of long-term, repeated photoinhibitory events and sustained reduction in PSII efficiency on net carbon gained is also assessed.;Winter wheat cultivars grown at 5{dollar}\sp\circ{dollar}C show light-saturated rates of CO{dollar}\sb2{dollar} exchange and apparent ...


The Organization Of The Maize Photosystem Ii Light-Harvesting Apparatus Under Normal And Chilling Conditions, Douglas A. Campbell Jan 1991

The Organization Of The Maize Photosystem Ii Light-Harvesting Apparatus Under Normal And Chilling Conditions, Douglas A. Campbell

Digitized Theses

The maize light harvesting system is structurally and functionally perturbed by chilling stress, with alterations in fluorescence parameters and protein processing. The molecular basis for these changes was investigated through biochemical analysis of the photosystem II-associated light-harvesting complexes (LHC II) of maize mesophyll thylakoids.;LHC II complexes from thylakoids were separated into three populations by mildly-denaturing electrophoresis. LHC II-1 contains four polypeptides and is equivalent to the oligomeric LHC IIb complex of Thornber et al. (1988). A less abundant oligomeric band, LHC II-2, contains a subset of the LHC IIb polypeptides, along with the LHC IIa complex (CP 29). The ...


Growth Temperature Effects On Photosynthesis And Photoinhibition Of Spinach (Spinacia Oleracea L), Steven Ray Boese Jan 1991

Growth Temperature Effects On Photosynthesis And Photoinhibition Of Spinach (Spinacia Oleracea L), Steven Ray Boese

Digitized Theses

Spinacea oleracea L. cv Savoy was utilized to determine the effects of growth temperature and temperature shifts after leaf expansion on growth, photosynthesis and photoinhibition.;Growth was slowed at 5{dollar}\sp\circ{dollar}C with the second leaves reaching full expansion at 92 days after planting compared to 32 days for 16{dollar}\sp\circ{dollar}C grown plants. Growth at 5{dollar}\sp\circ{dollar}C compared to 16{dollar}\sp\circ{dollar}C resulted in a 2 to 3 fold increases in leaf area, dry weight per area, and leaf thickness of fully expanded leaves. Further, growth ...


Rowcover Modification Of Carbon And Mineral Nutrient Partitioning In Strawberry (Fragaria Ananassa, Duch), Karen Lynn Brownlee Gast Jan 1988

Rowcover Modification Of Carbon And Mineral Nutrient Partitioning In Strawberry (Fragaria Ananassa, Duch), Karen Lynn Brownlee Gast

Doctoral Dissertations

In cool temperature climates where plant growth may be limited by short growing seasons and low temperature stress rowcovers are being used to increase production of fruit and vegetable crops. Two field experiments were conducted to investigate how floating rowcovers applied during autumn, winter and spring affect plant growth and development. The first experiment, 1985-86, examined mineral nutrient and biomass partitioning in a short-day cultivar, 'Sparkle', and a day-neutral cultivar, 'Fern', in rowcovered and nonrowcovered plants in autumn. The second experiment, 1986-87 examined carbon, nitrogen and biomass partitioning over time in autumn and in spring and development of yield components ...


Genetics And Physiology Of Cold Tolerance In Muskmelon (Cucumis Melo L), Mark Gordon Hutton Jan 1988

Genetics And Physiology Of Cold Tolerance In Muskmelon (Cucumis Melo L), Mark Gordon Hutton

Doctoral Dissertations

Five hundred muskmelon accessions were evaluated for germinability at 15$\sp\circ$C and classified as cold germinable (CG) or non-cold germinable (NCG). Accessions meeting the following criteria were classified as CG: germination $>$80%, EI $\leq$ 240, HI $\leq$ 265, and CI $\leq$ 290. EI, HI, and CI are mean hours to emergence, hypocotyl elongation and cotyledon expansion respectively. Only 5% of the accessions examined were considered as CG.

Seedling growth of CG (PI 126156, PI 126197, and 'Persia 202') and NCG ('Delicious 51', 'Minnesota Midget', 'Old Time Tennessee', Russian 4141) muskmelon genotypes was compared. Seedlings were grown to 30 ...


Polysome Metabolism In Winter Rye (Secale Cereale Cv Puma), Andre Laroche Jan 1987

Polysome Metabolism In Winter Rye (Secale Cereale Cv Puma), Andre Laroche

Digitized Theses

The effect of growth at low temperature on polysome metabolism in winter rye (Secale cereale cv Puma) has been investigated. A method for isolation of highly polymerized polysomes from mature leaf tissues has been developed. The degree of intactness of isolated polysomes was monitored by two independent but complementary methods: size class distribution on sucrose gradients and in vitro translation. The composition of the optimal polysome isolation buffer for mature rye leaves is similar for leaves grown at low (5{dollar}\sp\circ{dollar}) or high (20{dollar}\sp\circ{dollar}) temperature but different from that reported for young tobacco ...


Biosynthesis Of Peroxidase In Peanut Cells In Suspension Culture, Ravindra Nath Chibbar Jan 1984

Biosynthesis Of Peroxidase In Peanut Cells In Suspension Culture, Ravindra Nath Chibbar

Digitized Theses

Peroxidase (E.C.1.11.1.7) has been widely used as a marker of altered growth and development in plants. However, a definitive role of physiological significance has yet to be ascribed. This may be partially due to studies, that have been performed with a peroxidase molecule neither isolated to purity nor characterized from the system of investigation. A cationic peroxidase molecule (molecular weight 40 kD) had been purified to apparent homogenity and characterized from cultured peanut cells. Antibodies were raised against this peroxidase molecule in rabbits and used for monitoring biosynthetic studies on this peroxidase molecule in cultured ...


Kinetics, Regulation And Purification Of L-Phenylalanine Ammonia-Lyase From Germinating Lettuce Seeds (Phenylpropanoids, Enzyme, Alpha-Aminoxy - Beta-Phenylpropionic Acid), George Jose Kudakasseril Jan 1983

Kinetics, Regulation And Purification Of L-Phenylalanine Ammonia-Lyase From Germinating Lettuce Seeds (Phenylpropanoids, Enzyme, Alpha-Aminoxy - Beta-Phenylpropionic Acid), George Jose Kudakasseril

Doctoral Dissertations

The kinetics of L-phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) in germinating lettuce (Lactuca sativa cv. Grand Rapids) seeds was investigated. The Km of the enzyme was determined to be 4.2 x 10('-5) M. PAL in lettuce seeds did not show tyrosine ammonia-lyase activity. The nature of inhibition of PAL by various substrate analogues and phenylpropanoid compounds was studied. Substrate analogues like D-phenylalanine, p-fluorophenylalanine, (beta)-phenyllactic acid and tryptophan were found to inhibit PAL competitively whereas tyrosine did not show any inhibition of enzyme activity. Of the phenylpropanoids used, cinnamic acid was found to be a competitive ...


Electrophysiological Studies On Ulmus Americana, Jill Stanley Kathleen Shipman Jan 1982

Electrophysiological Studies On Ulmus Americana, Jill Stanley Kathleen Shipman

Doctoral Dissertations

Although membrane potentials have been measured in algal cells and in large cells of some higher plants, this investigation is the first to include such measurements in mesophyll cells of elm (Ulmus americana) leaves. The inquiry entailed the development of the technique for measuring elm leaf cell membrane potentials, the determination of membrane potentials expected of healthy, greenhouse elms, and the effects of various physical and chemical factors on the membrane potentials of elm leaf cells.

The membrane potential of a specific cell, was measured by amplifying the potential difference between a microelectrode inserted in the cell and a reference ...


Morpho-Physiological Factors Affecting Plant Productivity In Bush And Vine Forms Of Winter Squash (Cucurbita Maxima Duch), Cyril Emery Broderick Jan 1982

Morpho-Physiological Factors Affecting Plant Productivity In Bush And Vine Forms Of Winter Squash (Cucurbita Maxima Duch), Cyril Emery Broderick

Doctoral Dissertations

The productivity of a new bush winter squash cultivar ('Autumn Pride') was compared to that of 'Blue Hubbard', a high-yielding vine cultivar. Yields of 'Autumn Pride' increased with increasing plant density and, at high plant densities, were greater than yields of 'Blue Hubbard' at its near optimum plant density.

Several factors could have contributed to the higher yield potential of 'Autumn Pride'. CO(,2) compensation points were determined to be 38 ppm and 77 ppm CO(,2) for 'Autumn Pride' and 'Blue Hubbard', respectively, at 30(DEGREES)C. 'Autumn Pride' had two layers of palisade parenchyma cells, occupying 74 percent ...


Comparative Effects Of Gibberellic Acid And N(6)-Benzyladenine On Growth And Development Of Dwarf Watermelon Seedlings, Cheryl Diane Zack Jan 1981

Comparative Effects Of Gibberellic Acid And N(6)-Benzyladenine On Growth And Development Of Dwarf Watermelon Seedlings, Cheryl Diane Zack

Doctoral Dissertations

Apical applications of 0.2 micrograms N('6)-benzyladenine (BA), a synthetic cytokinin, or 5 micrograms gibberellic acid (GA) significantly enhanced hypocotyl elongation in intact dwarf watermelon seedlings. Accompanying the increase in hypocotyl length was increased expansion of the cotyledons and inhibition of root growth. A study on dry matter partitioning indicated that both hormones caused a preferential mobilization of metabolites from the cotyledons to the hypocotyl at an expense to roots. However, in comparison to untreated or GA-treated seedlings, BA decreased total translocation of metabolites out of the cotyledons. Hormonal effects on water potential of cotyledons and hypocotyls were ...


Aluminum Toxicity And Root Dna Synthesis In Wheat, Susan Ellen Ulmer Jan 1979

Aluminum Toxicity And Root Dna Synthesis In Wheat, Susan Ellen Ulmer

Retrospective Theses and Dissertations

No abstract provided.


The Role Of Potassium In Carbon-Dioxide Metabolism, Growth And Yield Of Alfalfa, Timothy Ree Peoples Jan 1978

The Role Of Potassium In Carbon-Dioxide Metabolism, Growth And Yield Of Alfalfa, Timothy Ree Peoples

Doctoral Dissertations

No abstract provided.


Study Of Peroxidase Isozymes From Culture Medium Of Peanut Cell Suspension, Om Prakash Srivastava Jan 1976

Study Of Peroxidase Isozymes From Culture Medium Of Peanut Cell Suspension, Om Prakash Srivastava

Digitized Theses

No abstract provided.


Altitudinal Variation Of Chlorophyll Concentration And Reflectance Of The Bark Of Populus Tremuloides, W.W. Covington Jan 1972

Altitudinal Variation Of Chlorophyll Concentration And Reflectance Of The Bark Of Populus Tremuloides, W.W. Covington

Aspen Bibliography

No abstract provided.