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United States Department of Agriculture

Agricultural Research Service

Research Project: CROP AND WEED RESPONSES TO INCREASING ATMOSPHERIC CARBON DIOXIDE
2006 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
The concentration of carbon dioxide in the atmosphere is increasing rapidly. In addition to its role in global warming, increased carbon dioxide has many direct effects on plants, including changes in growth rate and the quality of plant products. However, the effects of elevated carbon dioxide on plants differ greatly among species and with other environmental factors such as high temperature and drought. Because the mechanisms of responses are not sufficiently understood, these effects have proven very difficult to predict under field conditions. One purpose of this work is to increase our ability to adapt crops to the rising atmospheric carbon dioxide concentration itself and in combination with drought and high temperature stress. Another is to determine how responses to rising atmospheric carbon dioxide concentration may affect crop/weed competition and soil carbon sequestration under different weed and fertilizer management practices. This project is part of NP 204, Global Change, Ecosystem Impacts.


2.List by year the currently approved milestones (indicators of research progress)
The project plan lists milestones at 14, 36 and 60 months:

Objective 1, 14 months: Finish analysis of protein changes in Arabidopsis in response to elevated CO2, finish first season of comparisons of responses of photosynthesis and yield to CO2 in bean varieties, finish first experiments with soybean responses to elevated CO2 and heat stress. At 36 months: finish analysis of changes in gene expression in response to elevated CO2 in soybean meristems, complete the comparison of CO2 responses of the first set of bean varieties, finish studies of soybean responses to elevated CO2 and heat stress. At 60 months: finish studies of changes in gene expression at elevated CO2 in beans and soybeans, finish comparisons of responses to CO2 of a second set of bean varieties, finish studies of responses of soybeans to elevated CO2 and drought stress.

Objective 2, 14 months: Complete first year of competition between weeds and soybean/sorghum at elevated CO2, compare responses to sub-ambient to future CO2 concentrations in Canada thistle and other weeds, determine soybean losses due to Canada thistle at ambient and elevated CO2. At 36 months: report results of weed competition with soybean/sorghum crops at elevated CO2, report responses of invasive weeds to sub-ambient to future CO2 concentrations and begin work on wild oat responses, finish work on yield losses of soybeans due to Canada thistle, begin work on CO2 effects on herbicide efficacy. At 60 months: summarize the effects of elevated CO2 on carbon sequestration in the soybean/sorghum system, finish work on wild oat responses to rising atmospheric CO2, finish experiments on CO2 effects on herbicide efficacy in Canada thistle.

Objective 3, at 14 months: Complete first year, and determine if the fertilizer treatments are adequate. At 36 months: determine responses of photosynthesis and yield to nitrogen at ambient and elevated CO2. At 60 months: evaluate responses of carbon sequestration to nitrogen level at ambient and elevated CO2.


4a.List the single most significant research accomplishment during FY 2006.
"Carbon dioxide concentration at night affects soybean yield" work in the Crop Systems and Global Change Laboratory (CSGCL) has shown that elevated carbon dioxide treatments applied only during the daytime underestimate the response of seed yield of soybean to rising atmospheric carbon dioxide, in which carbon dioxide would be elevated continuously. Yield responses of soybean to elevated carbon dioxide in the SOYFACE facility have been anonymously small. This work provides a potential explanation and solution to this problem.

This accomplishment aligns with the NP 204 Action Plan, Agricultural Ecosystems Impacts, "Measure and predict plant responses (above and below-ground) to multiple interactions of abiotic and biotic stresses with rising carbon dioxide."


4b.List other significant research accomplishment(s), if any.
None.


4c.List significant activities that support special target populations.
None.


4d.Progress report.
Scientists in CSGCL identified 387 transcripts in maize plants that were differentially expressed in response to ambient and elevated carbon dioxide treatments. Experiments were performed with DNA microarrays made from over 7,000 ESTs from maize. Of the total, 227 maize transcripts were induced at least two fold in response to carbon dioxide enrichment. Most of the transcripts induced by elevated carbon dioxide had no known gene function or encoded unknown proteins, largely because the maize genome has not been sequenced. In spite of this, several maize genes involved in stomatal development and photosynthesis were induced by carbon dioxide enrichment. However, it was difficult to link the function of carbon dioxide responsive genes in maize with specific physiological responses.

During research on poison ivy scientists within CSGCL developed a novel method for extracting, analyzing, and quantifying the leaf urushiol content using gas chromatography coupled to mass spectrometry. Urushiols are a family of oily chemicals responsible for the immune response in humans after contact with the poison ivy plant. The research findings showed that total urushiol content was unchanged in ambient and elevated carbon dioxide but a chemical shift occurred resulting in urushiols with a greater degree of unsaturatation in the side chain. This was significant because the unsaturated forms of urushiol have greater bioactivity than the saturated forms.

Scientists in CSGCL demonstrated that recent increases in atmospheric carbon dioxide may be a factor in the biological success of cheatgrass (Bromus tectorum), an invasive species associated with the outbreak of fires in the Western United States. The growth and combustibility of cheatgrass is related to increases in atmospheric CO2 that occurred during the 20th century.

Scientists in CSGCL evaluated the effect of rising CO2 and temperature on the production of secondary alkaloids in weeds species that are associated with pharmacological products.

Scientists in CSGCL quantified that increasing carbon dioxide alters the percentage of ambient A 1, a surface protein on ragweed pollen associated with contact dermatitis.


5.Describe the major accomplishments to date and their predicted or actual impact.
"CO2 effects on proteins" work in CSGCL identified six proteins that were modified by growth at elevated carbon dioxide in Arabidopsis: myrosinase precursor, luminal binding protein 2, putative 3-beta hydroxysteroid dehydrogenase/isomerase protein, nucleoside dikinase II, major latex protein-related, and photosystem-II oxygen evolving complex 23. These findings indicate that, in addition to increasing photosynthesis, the rising carbon dioxide concentration in the atmosphere will also affect genes involved in plant defense and in the regulation of plant development. This work will be of interest to scientists trying to determine how plants will respond to rising atmospheric carbon dioxide.

This accomplishment aligns with the NP 204 Action Plan, Agricultural Ecosystems Impacts, "Measure and predict plant responses (above and below-ground) to multiple interactions of abiotic and biotic stresses with rising carbon dioxide."


6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
The knowledge that daytime-only elevation of carbon dioxide underestimates soybean yield responses to rising atmospheric carbon dioxide has been conveyed to ARS scientists directly involved in the SOYFACE experiment in Illinois. A new method of analyzing the urushiol content of poison ivy was developed and conveyed to other scientists attempting to quantify this compound.


7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
None.


Review Publications
Bunce, J.A. 2005. Seed yield of soybeans with daytime or continuous elevation of carbon dioxide under field conditions. Photosynthetica. 43:435-438.

Ziska, L.H., Emche, S.D., Johnson, E.L., George, K., Reed, D.R., Sicher Jr, R.C. 2005. Alterations in the production and concentration of selected alkaloids as a function of rising atmospheric carbon dioxide and air temperature: Implications for Ethno-pharmacology. Global Change Biology. 11: 7198-1807.

Derner, J.D., Schuman, G.E., Jawson, M.D., Shafer, S.R., Morgan, J.A., Polley, H.W., Runion, G.B., Prior, S.A., Torbert Iii, H.A., Rogers Jr, H.H., Bunce, J.A., Ziska, L.H., White, J.W., Franzluebbers, A.J., Reeder, S.J., Venterea, R.T., Harper, L.A. 2005. USDA-ARS global change research on rangelands and pasturelands. Rangelands. 27(5):36-42.

Bae, H., Kim, M.S., Sicher Jr, R.C., Bae, H., Bailey, B.A. 2006. Necrosis- and ethylene-inducing peptide (nep1) from fusarium oxysporum induces a complex cascade of transcripts associated with signal transduction and programmed cell death. Plant Physiology. 141:1056-1067.

Mohan, J.E., Ziska, L.H., Schlesinger, W.H., Thomas, R.B., Sicher Jr, R.C., George, K., Clark, J.S. 2006. Biomass and toxicity responses of poison ivy (Toxicodendron radicans) to elevated atmospheric CO2. Proceedings of the National Academy of Sciences. 103(24):9086-9089.

Bunce, J.A. 2005. What is the usual internal carbon dioxide concentration in C4 species under midday field conditions? Photosynthetica. 43:603-608.

Blank, R.R., White, R., Ziska, L. 2006. Combustion properties of bromus tectorum l.: influence of ecotype and growth under four co2 concentrations. International Journal of Wildland Fire. 15:227-236

Last Modified: 11/28/2014
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