CURRENT RESEARCH PROJECTS
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CO2-induced changes in heat-shock proteins (HSPs) and photosynthetic tolerance to acute heat stress.
Ecological physiology of plant chloroplast small heat-shock proteins.
Proteonomic and physiological analysis of nutritional stress in plants.
Effects of global environmental change on plant-soil microbe linkages.
Assessing the role of turbid river plumes in the development of Microcystis blooms in Lake Erie with molecular techniques.
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CO2-induced changes in heat-shock proteins (HSPs) and photosynthetic tolerance to acute heat stress
PI: Scott A. Heckathorn, University of Toledo
Co-PI: EW (Bill) Hamilton, Washington & Lee University
Post-doctoral Researcher: Deepak Barua
Graduate students: Dan Wang, Puneet Joshi, Kumar Mainali, Rajan Tripathee
Funding: Collaborative grants to SAH & EWH funded by the National Science Foundation, Ecological & Evolutionary Physiology Program, Summer 2004-Summer 2008.
The major objective of this project is to investigate the effect of elevated atmospheric CO2 on HSP production in plants of different functional types and with different tolerances to heat stress, how CO2 and changes in HSPs affect tolerance of photosynthesis to acute heat stress, how CO2 effects are influenced by nitrogen availability and growth temperature, and how the balance of basal-to-inducible thermotolerance is affected by these factors.
Ecological physiology of plant chloroplast (and, to a lesser extent, mitochondria) small heat-shock proteins
PI: Scott A. Heckathorn, University of Toledo
Co-PI: Dawn S. Luthe, Mississippi State University (now at Penn State Univ.)
Co-PI: EW (Bill) Hamilton, Washington & Lee University
Post-doctoral researcher: Bill Hamilton (and later, Assist. Prof.)
Graduate student: Deepak Barua
Funding: Collaborative grants to SAH/EWH & DSL funded by the National Science Foundation, Ecological & Evolutionary Physiology Program, Summer 2001-Summer 2004/5.
The project makes a cover story in a journal
The major objective of this project is to investigate natural variation in chloroplast small HSP genes and proteins among and within plant species (especially heat-tolerant vs. -sensitive genotypes), and the functional consequences of this natural variation for protecting electron transport and other aspects of photosynthesis.
Biomonitoring of nutritional and environmental stress in plants
Co-PI: John Gray, University of Toledo
Co-PI: Scott Heckathorn, University of Toledo
Co-PI: Jonathan Frantz, USDA-ARS & Univ. of Toledo
Post-doctoral researchers: Futong Yu, Sasmita Mishra
Graduate students: Mei Chen, Ying Deng
Funding: USDA Specific Cooperative Agreement, 2004-2008.
In this project, we are using genomic and proteonomic tools (the Gray and Heckathorn labs, respectively) to identify genes and proteins expressed in horticultural plants (e.g., geranium) during early stages of nutritional stress (deficiency and toxicity, primarily of the micronutrient Boron). Initial studies are being conducted with Arabidopsis thaliana, and are focused on boron nutrition. One project goal is to develop bioassays to be used by growers to identify, and thereby limit, nutrient stress prior to development of visible damage.
Effects of global environmental change on plant-soil linkages
Co-PI: Scott Heckathorn (University of Toledo)
Co-PI: Von Sigler (University of Toledo)
Co-PI: Bill Hamilton (Washington & Lee University)
Graduate students: Issmat Kassem, Puneet Joshi, Kumar Mainali
The objectives of this research are to explore the impact of global environmental change factors (namely CO2, heat stress, precipitation, and nitrogen) on interactions between plants and soil (i.e., plant C or N loss to soil, plant soil-N uptake, and microbial activity, growth, and composition). We are using the dominant warm-season C4 prairie grass, Andropogon gerardii (big bluestem), as a model plant, and a variety of tools, including stable isotope labeling and DNA profiling, to examine how elevated CO2, drought, and summer heat waves affect plant-soil interactions.
In one completed study, led by Issmat Kassem, we found that elevated CO2 alone increased microbial growth and carbon use and changed community structure in response to increased soil %C (likely from root exudation). Also, elevated CO2 limited drought-related decreases in microbial activity, which likely resulted from decreased plant water use at elevated CO2.
In a second study, led by Kumar Mainali, a set of studies in the lab and field revealed that heat waves (1) increased plant C loss to soil (presumably via fine-root turnover); (2) increased total plant N uptake (due to increased root mass), but decreased the efficiency of N uptake per gram of root; (3) decreased soil (root and microbe) respiration and root exudation, yet increased microbial biomass. Therefore, heat waves affected plant-soil linkages in this system, often to the detriment of the plant and to the benefit of soil microbes.
Assessing the role of turbid river plumes in the development of Microcystis blooms in Lake Erie with molecular techniques
PI: Tom Bridgeman, University of Toledo
Co-PI: Christine Mayer, University of Toledo
Co-PI: Scott Heckathorn, University of Toledo
Co-PI: Von Sigler, University of Toledo
Funding: Ohio SeaGrant, 2007-2008.
Microcystis bloom near Maumee Bay, Lake Erie, August 19, 2003 (photos: OhioView, T. Bridgeman)
In August 2003 and 2004, massive blooms of the cyanobacterium, Microcystis aeruginosa, formed in western Lake Erie and persisted for nearly a month (Figure 1). Surface scums of Microcystis containing high concentrations of the toxin microcystin washed ashore in Michigan and Ohio, resulting in foul-smelling, rotting, algal mats. Beaches and recreational boating areas were rendered unusable and sport fishing was adversely affected. The Microcystis bloom of 2003 was perhaps the most severe in Lake Erie’s recent history, but of greater concern is a trend towards increasing frequency of Microcystis blooms in the last decade. Based on our field observations in 2003 and 2004, we hypothesize that low-light and high-nutrient conditions in the Maumee River plume may potentially explain why outer Maumee Bay, the epicenter of both 2003 and 2004 blooms, is especially prone to bloom formation. We will test our hypothesis using a combination of traditional field measurements and recently-developed molecular and physiological techniques. Recommendations resulting from this research may include controls on sediment loading and shifts in the timing of dredging activity.
