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United States Department of Agriculture

Agricultural Research Service

Research Project: ENVIRONMENTAL EFFECTS ON PHYTOCHEMICALS IN FOOD CROPS: CONNECTING GLOBAL CHANGE AND HUMAN NUTRITION
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?
This project is a multidisciplinary team effort that addresses primarily interactions between atmospheric CO2 and multiple stresses with respect to plant quality as outlined in the "Cropping Systems" Problem Area of Component III, "Agricultural Ecosystems," of National Program 204 - Global Change and project #5 "Identifying the health promoting properties of plant and animal foods" of National Program 107 - Human Nutrition.

Plants contain a wide range of organic compounds with known or putative nutritive or anti-nutritive functions in humans. Many of these compounds are also involved in the adaptation or resistance of plants to stress and are altered by environment during plant growth. But more detailed information is needed to assess the impact on crop nutritional properties of both current fluctuations in weather (e.g., temperature or drought) as well as potential changes in climate predicted to accompany on-going increases in atmospheric greenhouse gases. Indications are that climate is changing faster than at any time in recent history, so it is important to develop this information. In addition to more precise characterization of multiple and potentially interacting factors such as atmospheric CO2, temperature, and soil moisture, studies are needed to monitor a wide range of phytochemicals in an appropriate mix of crop species and genetic lines. Since warm temperatures are more likely to occur earlier rather than later in the growing season, it will be important to characterize the effect of environment with respect to the stage of seed development. Information from this project should assist plant scientists to evaluate and improve the ability of plants to adapt to altered environments through improved crop management and/or breeding strategies that will maximize benefits and minimize adverse effects of extremes in weather or shifts in climate. In addition, this work should enhance the ability of crop scientists to predict levels of plant nutrients in response to the growing environment. For example, recommendations emphasizing the consumption of particular crops for their nutrient content depend on knowledge of those levels. However, some known or suspected nutrients are highly variable in concentration; environment likely influences this variability, but detailed information is generally lacking. Results will also assist in the development of techniques to generate crops enriched or depleted in specific compounds, either to improve the nutritional composition of commodities or to evaluate the nutritional effects of specific phytonutrients for humans or animals.


2.List by year the currently approved milestones (indicators of research progress)
FY 2006 Complete method development for additional phytonutrients.

Study 1 (Greenhouse Temperature x Drought x Cultivar): finish analysis of soybean tocopherols and isoflavones. Study 2 (Growth Chamber Temperature Response Characterization): finish analysis of soybean tocopherols and isoflavones. Study 3 (Growth Chamber CO2 x Temperature x Drought): finish analysis of soybean tocopherols and isoflavones. Study 5 (Field CO2 Enrichment): start analysis of soybean tocopherols. Study 6 (Greenhouse CO2 x Temperature): analyze soybean, rice or peanut tocopherols, tocotrienols, or phytosterols. Study 8 (Seed Stage Specific Temperature Effects x CO2): analyze soybean tocopherols and isoflavones. Study 9 (Effects of Weather on Tocopherols and Isoflavones): analyze soybean isoflavones and tocopherols.

FY 2007 Study 1: analyze soybean phytosterols or saponins. Study 2: analyze soybean phytosterols or saponins. Study 3: analyze soybean phytosterols or saponins. Study 4 (Maryland Uniform Soybean Trials, 1999-2002): analyze soybean phytosterols or saponins. Study 5: continue analysis of soybean tocopherols. Study 6: continue analysis of soybean, rice or peanut tocopherols, tocotrienols, or phytosterols. Study 8: continue analysis of soybean tocopherols and isoflavones. Study 9: continue analysis of soybean tocopherols and isoflavones.

FY 2008 Study 1: complete and prepare report. Study 2: complete and prepare report. Study 3: complete and prepare report. Study 4: complete and prepare report. Study 5: continue analysis of soybean tocopherols. Study 6: continue analysis of soybean, rice or peanut tocopherols, tocotrienols, or phytosterols. Study 7 (Identify Temperature Sensitive Stages of Soybean Seed Development Affecting Tocopherols and Isoflavones): initiate and begin analyses of tocopherols and isoflavones. Study 8: complete and prepare report. Study 9: continue analysis of soybean isoflavones and tocopherols.

FY 2009 Study 5: continue analysis of soybean tocopherols. Study 6: continue analysis of soybean, rice or peanut tocopherols, tocotrienols or phytosterols. Study 7: analyze soybean isoflavones and tocopherols and assess efficacy of treatments. Study 9: continue analysis of soybean isoflavones and tocopherols.

FY 2010 Study 5: complete and prepare report. Study 6: complete and prepare report. Study 7: complete and prepare report. Study 9: complete and prepare report.


4a.List the single most significant research accomplishment during FY 2006.
Elevated temperatures in controlled environments (growth chambers or greenhouses) during soybean seed maturation were previously shown to increase the proportion of alpha-tocopherol and decrease the proportion of delta-tocopherol in mature seed. Although field-grown soybeans also had elevated alpha- and diminished delta-tocopherol when grown in warm regions or during hot, dry years, it is unclear whether a brief episode of elevated temperature or drought is sufficient to elicit a significant change. Controlled environments were used to provide a 1-week period of high temperature (+7 deg. C) or drought (withholding water) midway through seed development. Analysis of tocopherols revealed a small but highly significant increase in alpha-tocopherol in seeds from droughted plants compared to seeds from control or elevated temperature plants, indicating that even brief exposure to stress conditions can alter phytochemical composition in seeds. This work addresses primarily interactions between atmospheric CO2 and multiple stresses with respect to plant quality as outlined in the "Cropping Systems" Problem Area of Component III, "Agricultural Ecosystems," of NP 204. In addition, results are relevant for the "Climate and Weather Variability and Extremes" section of Component IV, "Changes in Weather and the Water Cycle at Farm, Ranch, and Regional Scales," which includes work to predict agricultural productivity under variable and extreme climate and weather conditions and to develop production, management, and mitigation alternatives.


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


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


4d.Progress report.
None.


5.Describe the major accomplishments to date and their predicted or actual impact.
Atmospheric CO2 is projected to double by the end of this century and may result in global warming. It is important to determine how such changes will affect crops and food quality. Consequently, the effect of elevated temperature during rice seed maturation on gamma-oryzanols, a family of about 12 different ferulylated phytosterols, was studied. The function of gamma-oryzanols in plants is not known, but they are good antioxidants are thought to be one of the factors underlying hypocholesterolemic effects of rice bran oil. Elevated temperatures during rice seed maturation was previously shown to increase total tocopherols and tocotrienols, including vitamin E (i.e., alpha-tocopherol), in rice seeds obtained from six different varieties that were raised to seed maturity in three replicate temperature gradient greenhouses (i.e., ambient at one end and elevated +4.5 deg. C at the other end). Levels of total gamma-oryzanols increased about 30% in seeds from elevated temperatures. Most of the increase resulted from an increase in one compound, ferulyl-24-methylene cycloartenol. Implications for biosynthesis of phytosterols and nutrition are being analyzed. These results show how amounts of phytonutrients in an important crop are affected by environment, potentially altering both the monetary and nutritional value of the crop. These results should be of interest to farmers, consumers, nutritionists, plant scientists, breeders and policymakers evaluating impacts of global change.


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?
None.


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).
Wang, S., McKay, B. 2006. More reasons to eat your veggies. The Wall Street Journal On-Line, July 25, 2006, p. D1.


Review Publications
Caldwell, C.R., Britz, S.J. 2006. Effect of supplemental ultraviolet radiation on the carotenoid and chlorophyll composition of green house-grown leaf lettuce (lactuca sativa l.)cultivars. Journal of Food Composition and Analysis. 19:617-644.

Last Modified: 12/24/2014
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