Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 26 of 26

Full-Text Articles in Life Sciences

Carbon And Nitrogen Dynamics In Plants Grown At Low Co2 Conditions Of The Past, Andre Galvao Duarte Sep 2019

Carbon And Nitrogen Dynamics In Plants Grown At Low Co2 Conditions Of The Past, Andre Galvao Duarte

Electronic Thesis and Dissertation Repository

For most of the recent evolutionary history of plants, atmospheric CO2 concentrations have been far below modern values. However, little is known about how plants grown in a low CO2 environment balance their carbon demand for growth while meeting their requirement for nitrogen acquisition, the establishment of mycorrhizal fungal associations, and the production of defense compounds. Here, I investigated how low CO2 affects Elymus canadensis and Picea mariana by comparing their growth at low and current CO2 concentrations. I found that reduced N availability exacerbated low CO2 effects on growth, and reduced stomatal index and ...


Greening Rates And Photosynthetic Development Of Leaves In C3 And C4 Plants, Tayler J. Kriss Jan 2019

Greening Rates And Photosynthetic Development Of Leaves In C3 And C4 Plants, Tayler J. Kriss

Master's Theses

To study chlorophyll development time and overall photosynthetic development in C3 and C4 leaves, seeds were germinated in complete darkness and achlorophyllous leaves were then allowed to develop in lighted conditions. Corn (Zea mays, C4), sorghum (Sorghum bicolor, C4), green bean (Phaseolus vulgaris, C3), broad bean (Vicia faba, C3), and wheat (Triticum aestivum, C3) were investigated for the first ten days of sunlight exposure. Chlorophyll concentration, chlorophyll fluorescence, and CO2 gas exchange measurements were conducted daily on the first leaf that emerged after the embryonic leaves of each plant. The first five days of the experiment, days zero to four ...


Optimizing The Use Of A Liquid Handling Robot To Conduct A High Throughput Forward Chemical Genetics Screen Of Arabidopsis Thaliana, B. Kirtley Amos, Victoria G. Pook, Seth Debolt Apr 2018

Optimizing The Use Of A Liquid Handling Robot To Conduct A High Throughput Forward Chemical Genetics Screen Of Arabidopsis Thaliana, B. Kirtley Amos, Victoria G. Pook, Seth Debolt

Horticulture Faculty Publications

Chemical genetics is increasingly being employed to decode traits in plants that may be recalcitrant to traditional genetics due to gene redundancy or lethality. However, the probability of a synthetic small molecule being bioactive is low; therefore, thousands of molecules must be tested in order to find those of interest. Liquid handling robotics systems are designed to handle large numbers of samples, increasing the speed with which a chemical library can be screened in addition to minimizing/standardizing error. To achieve a high-throughput forward chemical genetics screen of a library of 50,000 small molecules on Arabidopsis thaliana (Arabidopsis), protocols ...


Variation In Mechanical Strength Of Ferns In The Santa Monica And Santa Cruz Mountains, Helen I. Holmlund Jul 2013

Variation In Mechanical Strength Of Ferns In The Santa Monica And Santa Cruz Mountains, Helen I. Holmlund

Featured Research

Mentor: Stephen D. Davis

In recent years, experts in plant physiology have begun to explore the functional traits of ferns, especially in regards to their tissue-water relations. However, to our knowledge, no scientist had yet examined the relationship between fern biomechanics and physiology. We examined the mechanical properties of fern stipes (stems) and attempted to relate those properties to ecological and physiological traits. Based on our knowledge of fern anatomy, we hypothesized that stipe mechanical strength would not correlate with cavitation resistance as it does in seed-bearing plants. This assertion that mechanical strength will not relate to cavitation resistance begs ...


Emerging Technologies For Non-Invasive Quantification Of Physiological Oxygen Transport In Plants, P. Chaturvedi, M. Taguchi, S. L. Burrs, B. A. Hauser, W.W. A.W. Salim, Jonathan C. Claussen, E. S. Mclamore Jan 2013

Emerging Technologies For Non-Invasive Quantification Of Physiological Oxygen Transport In Plants, P. Chaturvedi, M. Taguchi, S. L. Burrs, B. A. Hauser, W.W. A.W. Salim, Jonathan C. Claussen, E. S. Mclamore

Jonathan C. Claussen

Oxygen plays a critical role in plant metabolism, stress response/signaling, and adaptation to environmental changes (Lambers and Colmer, Plant Soil 274:7-15, 2005; Pitzschke et al., Antioxid Redox Signal 8:1757-1764, 2006; Van Breusegem et al., Plant Sci 161:405-414, 2001). Reactive oxygen species (ROS), by-products of various metabolic pathways in which oxygen is a key molecule, are produced during adaptation responses to environmental stress. While much is known about plant adaptation to stress (e.g., detoxifying enzymes, antioxidant production), the link between ROS metabolism, O2 transport, and stress response mechanisms is unknown. Thus, non-invasive technologies for measuring O2 ...


Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong Jan 2006

Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong

Retrospective Theses and Dissertations

Autophagy is a process in which cytoplasmic components are degraded in the vacuole. It occurs when organisms are subjected to environmental stress conditions or during certain stages of development. Upon induction of autophagy, a portion of cytoplasm is surrounded by a double membrane structure to form an autophagosome. The outer membrane of the autophagosome then fuses with the vacuole and the inner membrane and its contents are degraded by vacuolar hydrolases. The morphological characteristics of autophagy have been observed in plants for decades and several autophagy defective mutants have been isolated recently; however, little is known about the molecular mechanism ...


Carbohydrate Partitioning And Photosynthesis In Arabidopsis Thaliana , Dan Joseph Stessman Jan 2004

Carbohydrate Partitioning And Photosynthesis In Arabidopsis Thaliana , Dan Joseph Stessman

Retrospective Theses and Dissertations

To characterize carbohydrate partitioning and photosynthesis in Arabidopsis thaliana we examined three different lines: wild type Columbia ecotype, immutans, and T-DNA knockouts of vacuolar acid invertase. Wild type plants displayed decreasing photosynthesis from the beginning of leaf expansion through senescence. Chlorophyll, total soluble protein, and expression of LhcB also declined in a similar fashion. Pulse-label feeding of 14C showed a peak flux into glucose and fructose coincident with full leaf expansion a large decrease in LhcB expression. However, flux of 14C into the different carbohydrate fractions did not reflect carbohydrate pool sizes. The conclusion was that flux into the different ...


Investigating The Influence Of Cadmium Stress On Glutathione Metabolism Utilizing Mutant And Transgenic Arabidopsis Plants , Annita Gatherum Peterson Jan 2004

Investigating The Influence Of Cadmium Stress On Glutathione Metabolism Utilizing Mutant And Transgenic Arabidopsis Plants , Annita Gatherum Peterson

Retrospective Theses and Dissertations

Glutathione (GSH) has long been known to be an essential molecule in a number of important basic cellular functions including detoxification of reactive oxygen species, transport and storage of organic sulfur, and regulation of the cell cycle. Furthermore, GSH is essential in the detoxification of some heavy metals including cadmium through the production of phytochelatins. Because the accounts of heavy metal pollution are increasing due to human activities, heavy metal toxicity in plants is an important topic of study. To investigate the role of GSH-related functions in response to cadmium exposure I examined three distinct levels of GSH involvement in ...


Three Amino Acid Loop Extension (Tale) Transcription Factors That Regulate Potato (Solanum Tuberosum L) Tuberization , Hao Chen Jan 2003

Three Amino Acid Loop Extension (Tale) Transcription Factors That Regulate Potato (Solanum Tuberosum L) Tuberization , Hao Chen

Retrospective Theses and Dissertations

Homeodomain (HD) proteins play an important role in cell fate determination and body plan definition by binding to regulatory regions of key target genes. Using the yeast two-hybrid system and a potato KNOX HD protein, POTH1, as bait, seven distinct interacting proteins have been identified from a potato (Solanum tuberosum L.) stolon library. All seven cDNAs belong to the BEL1-like family of transcription factors. Through deletion mutation analysis, we identified a protein-binding domain present in the carboxy-end of the KNOX domain of POTH1. The protein-binding domain in the BEL protein is located in the amino-terminal half of the 120-residue conserved ...


The Structure-Function Relationships Of Maize Starch Synthase, Zhong Gao Jan 2001

The Structure-Function Relationships Of Maize Starch Synthase, Zhong Gao

Retrospective Theses and Dissertations

This research was to study the structure-function relationships and catalytic mechanisms of maize starch synthase IIa (SSIIa). Chemical modification of maize SSIIa showed that pyridoxal-5-phosphate, which specifically modifies lysine residues, inactivated maize SSIIa activity in a time and concentration dependent manner. Substrate ADP-glucose completely protected SSIIa from inactivation by pyridoxal-5-phosphate, indicating that lysine residue(s) is important for ADP-glucose binding of maize SSIIa. To identify lysine residues possibly involved in substrate ADP-glucose binding, site-directed mutagenesis was used to generate mutants at conserved lysine sites. Lysine-193 located at the conserved KTGGL domain has been widely suggested as a putative ADP-glucose binding ...


Insertional Mutagenesis Of The Signal Transduction Pathway For Low Co2 Acclimation In Chlamydomonas Reinhardtii , Kyujung Van Jan 2001

Insertional Mutagenesis Of The Signal Transduction Pathway For Low Co2 Acclimation In Chlamydomonas Reinhardtii , Kyujung Van

Retrospective Theses and Dissertations

Chlamydomonas reinhardtii shows adaptive changes in order to survive in limiting CO2 conditions because they live in quite variable conditions of CO2 availability. We are trying to identify mutants defective in the acclimation response to limiting CO 2. Nuclear transformation to complement an Arg- phenotype was used to generate insertional mutants, and Cah1 expression and having high CO2-requiring (HCR) phenotype were used as reporters for induction of genes involved in acclimation to limiting CO 2.;Among a collection of insertionally generated mutants, a mutant has been isolated that showed no pCA1 protein and no Cah1 mRNA. This mutant strain, designated ...


The Wheat Book : Principles And Practice, W K. Anderson, J R. Garlinge Jan 2000

The Wheat Book : Principles And Practice, W K. Anderson, J R. Garlinge

Bulletins 4000 -

Contents : Environment / revised by J. Cramb, J. Courtney and P. Tille - The structure and development of the cereal plant / revised by T.L. Setter and G. Carlton - Germination, vegetative and reproductive growth / revised by T.L. Setter and G. Carlton - Crop water use / D. Tennant - Nutrition / revised by M.D.A. Bolland, R.F. Brennan, J.W. Bowden, M.G. Mason, N.K. Edwards, M.M. Riley and S.W. Gartrell - Wheat in farming systems / revised by B. Bowden, P. Blackwell, P. Carmody, M. Ewing, R. Kingwell, R. L ghman, I. McFarlane, P. Michael, P. Nelson, I. Pritchard, C. Revell ...


Changes In Physiology, Molecular Biology, And Biochemistry Associated With Maize Seedlings Germinated From Freeze-Damaged Seed , Jack Alan Hartwigsen Jan 1999

Changes In Physiology, Molecular Biology, And Biochemistry Associated With Maize Seedlings Germinated From Freeze-Damaged Seed , Jack Alan Hartwigsen

Retrospective Theses and Dissertations

Injury to immature maize seed caused by early season frost is of great economic concern to seed producers. Surprisingly, there has been very little research investigating the adverse effects of freezing on immature seed and the resulting biochemical changes in seedlings germinated from freeze damaged seed. In this three part study, we investigated the effects of freezing injury, first as they pertained to the overall viability of the seed, then to how exposure of immature seed to freezing induces biochemical changes in seedlings germinated from these seed. We found that the extent of freezing injury as determined by reduced viability ...


Seed Development Of Shrunken-2 Sweet Corn (Zea Mays L.) And The Use Of Film Coating And Field Chemical Applications To Improve Seed Quality , Xianming Duan Jan 1997

Seed Development Of Shrunken-2 Sweet Corn (Zea Mays L.) And The Use Of Film Coating And Field Chemical Applications To Improve Seed Quality , Xianming Duan

Retrospective Theses and Dissertations

This study investigated the impacts of shrunken-2 (sh2) endosperm mutation on sweet corn embryogenesis and germination acquisition during seed development and maturation. Comparison between three pairs of sh2 and sugary (su) isogenic inbred lines and two dent corn inbreds showed that sh2 not only reduced the endosperm reserve accumulation, but also significantly retarded embryo development, especially during early seed development, resulting in a smaller embryo after maturation. Developing seed of sh2 lines acquired the same germinability at least 10 days later than su and dent corn seeds. During the late maturation stage, the germinability of sh2 seeds tended to decline ...


Effect Of Weed Water Stress On Postemergence Herbicide Activity , Emilio Sabas Oyarzabal Jan 1991

Effect Of Weed Water Stress On Postemergence Herbicide Activity , Emilio Sabas Oyarzabal

Retrospective Theses and Dissertations

Shattercane (Sorghum bicolor (L.) Moench) and woolly cupgrass (Eriochloa villosa (Thunb.) Kunth) growing under water stress conditions suffer morphological and physiological changes that may affect the activity of postemergence herbicides. Morphological and physiological changes in shattercane and woolly cupgrass growing under different levels of water stress were determined. Leaf area expansion was the growth variable most affected in both species. Both plants exhibit decreased dry matter accumulation due to water stress treatments. Woolly cupgrass stomatal conductance was more affected by water stress than shattercane. Photosynthesis was greatly reduced in both weeds, but only partially related to decreased stomatal conductance, indicating ...


Characterization Of The Alternative Respiratory Pathway In Soybean , David Michael Obenland Jan 1989

Characterization Of The Alternative Respiratory Pathway In Soybean , David Michael Obenland

Retrospective Theses and Dissertations

The alternative respiratory pathway may be important in the energy economy of higher plants. The objective of this study was to characterize the alternative pathway in soybean and to gain a better understanding of the importance of this respiratory pathway to soybean productivity;Capacity for the alternative pathway was assessed in leaf and root tissue of male-sterile and fertile soybean plants and in leaf, embryonic axis and epicotyl tissue, as well as isolated mitochondria, of pea (Pisum sativum L.) by measurement of oxygen uptake in the presence and absence of KCN and salicylhydroxamic acid (SHAM). Male-sterile and fertile soybean tissues ...


Seed Dormancy In Pennsylvania Smartweed And Barnyardgrass , James Lowell Jordan Jan 1981

Seed Dormancy In Pennsylvania Smartweed And Barnyardgrass , James Lowell Jordan

Retrospective Theses and Dissertations

The competitive effects of maize plants on weed growth, seed production, and seed dormancy were investigated. Weed seed dormancy was studied using ultrafreezing and electron microscope techniques. The importance of weed seed dormancy in weed control was discussed;Plants of four weed species, Setaria luteschens (Weigel) Hubb., Setaria viridis (L.) Beauv., Polygonum pensylvanicum L., and Abutilon theophrasti Medic., were grown free from competition with maize. Height of Pennsylvania smartweed and velvetleaf plants increased for plants in competition with maize plants; other plant growth parameters decreased. Plant growth and seed production for green and yellow foxtail decreased for plants that were ...


Oxygen And Carbon Dioxide Effects On The Photosynthetic And Photorespiratory Carbon Pools In Glycine Max, William D. Hitz Jan 1979

Oxygen And Carbon Dioxide Effects On The Photosynthetic And Photorespiratory Carbon Pools In Glycine Max, William D. Hitz

Retrospective Theses and Dissertations

No abstract provided.


Primary Phloem Regeneration Without Concomitant Xylem Regeneration: Controlling Factors In Coleus Blumei , Duane Francis Houck Jan 1973

Primary Phloem Regeneration Without Concomitant Xylem Regeneration: Controlling Factors In Coleus Blumei , Duane Francis Houck

Retrospective Theses and Dissertations

No abstract provided.


Responses Of Yeast To 2,4-D , Charles Richard Swanson Jan 1953

Responses Of Yeast To 2,4-D , Charles Richard Swanson

Retrospective Theses and Dissertations

No abstract provided.


Determination Of Moisture In Seeds , Ashley Monroe Bryan Jan 1953

Determination Of Moisture In Seeds , Ashley Monroe Bryan

Retrospective Theses and Dissertations

The moisture content of samples of corn and soybeans were determined by five different methods, which included oven methods, drying under vacuum over magnesium perchlorate distillation methods, and an electrical conductivity method;The methods yielded varying results. It was observed that vacuum drying at 100°C or 70°C gave the most consistent results, while fluctuations were the greatest at 135°C. The highest moisture values were obtained in the 100°C vacuum oven, while Tag-Heppenstall method, as standardized, always underestimated these results. The Brown-Duvel distillation method underestimated moisture content except at higher moisture levels of the seeds;Vacuum desiccator ...


Physiologic Responses Of Bromus Inermis , Darrel Seymour Metcalfe Jan 1950

Physiologic Responses Of Bromus Inermis , Darrel Seymour Metcalfe

Retrospective Theses and Dissertations

No abstract provided.


Physiological Changes And Freezing Injury In Maturing Maize , Mohamed Mohamed Aboul-Ela Jan 1950

Physiological Changes And Freezing Injury In Maturing Maize , Mohamed Mohamed Aboul-Ela

Retrospective Theses and Dissertations

No abstract provided.


Effects Of Light And Other Factors On Germination Of Seed Of Poa Pratensis , Louis Nelson Bass Jan 1949

Effects Of Light And Other Factors On Germination Of Seed Of Poa Pratensis , Louis Nelson Bass

Retrospective Theses and Dissertations

No abstract provided.


Physiological Studies Of Weed Seed Germination , Robert Owen Bibbey Jan 1946

Physiological Studies Of Weed Seed Germination , Robert Owen Bibbey

Retrospective Theses and Dissertations

Environmental influences on the after-ripening and dormancy of seeds of a number of species were studied in the field and laboratory;Environmental dormancy is defined as the type of dormancy affecting a readily germinable seed when it was prevented from germinating by absence of some essential environmental factor or by the presence of some inhibitor, and seed dormancy, embracing both primary and secondary types, as the dormancy existing in a seed which fails to germinate under apparently satisfactory germinating conditions;The after-ripening of seeds of Thlaspi arvense, Brassica arvensis and Avena fatua was studied (1) in fine sandy loam, (2 ...


The Relation Of Root Reserves To Cold Resistance In Alfalfa , Jesse Jarue Mark Jan 1935

The Relation Of Root Reserves To Cold Resistance In Alfalfa , Jesse Jarue Mark

Retrospective Theses and Dissertations

Roots from Grimm alfalfa that had been subjected to different cutting treatments were collected during summer, fall, and winter and the amount of reserves determined;Frequent cutting checked root growth 50 percent or more. The root reserves were higher in the uncut plants than in the cut plants. The period of greatest difference was during October and November;The amount of reserve materials in the roots of cut and uncut plants was positively correlated with cold resistance in both artificial freezing tests and in field tests;The starch and dextrin decreased in autumn and early winter. The non-reducing sugars increased ...