IDENTIFYING AND MANIPULATING DETERMINANTS OF PHOTOSYNTHATE PRODUCTION AND PARTITIONING
Global Change and Photosynthesis Research
2011 Annual Report
1a. Objectives (from AD-416)
Objective 1: Define the key regulatory elements controlling photosynthate partitioning and nitrate assimilation and their interactions; develop and begin to test strategies to modify those processes for agricultural purposes.
Objective 2: Determine the mechanistic basis for limitations on photosynthetic performance including those imposed by agriculturally significant stresses.
Objective 3: Establish the major features controlling the response of photosynthetic productivity in soybean and corn to elevated atmospheric CO2, tropospheric ozone, and their interactions with drought and temperature, explore the bases for genetic variability in responses, and test potential transgenic amelioration strategies.
Objective 4: Determine the environmental impacts of land cover change associated with alternative bioenergy crops.
1b. Approach (from AD-416)
Investigate isoform specificity for nitrate reductase (NR) posttranslational modification in vivo, and elucidate the impact of 14-3-3 binding on NR protein degradation. Localize the membrane binding site(s) on sucrose synthase and identify factors that may control the interaction. Use high-resolution spatial and temporal analysis of leaf growth to identify specific areas where leaf growth is occurring. Determine the biochemical factors responsible for the lower activation state of Rubisco, at high temperatures and test potential transgenic amelioration strategies. Further elucidate the role of Rubisco activase in thermal sensitivity/tolerance. Determine the biochemical basis for the "Green Seed Problem" of canola. Perform metabolite analysis of growing leaves under elevated CO2 and O3 to identify key components that may be involved in controlling growth. Determine the factors that lower the activation state of Rubisco under sink- and/or N-limited conditions, which are often encountered when plants are grown under high CO2. Explore the interaction of elevated CO2 with drought on soybean performance. Explore the interaction of elevated CO2 with temperature on soybean and corn performance. Determine if growth at elevated CO2 enhances or ameliorates oxidative stress. Determine the impact of land cover change from row crops to perennial grasses on hydrological cylce and carbon biosequestration.
3. Progress Report
Experiments are underway to investigate the effect of the predicted increase in the frequency and severity of heat waves on both corn and soybean production. Three meter diameter plots of soybean were warmed by 6°C for three consecutive days during three different developmental stages for each crop to test the dual hypothesis that 1) warming during reproductive stages of corn and soybean development will have the largest negative effects but that 2) heat waves during reproductive developmental phases will have much greater yield impact because the much longer flowering interval in soybean will allow for yield compensation by later flowering. A full suite of physiological and agronomic measurements are being conducted just prior to, during and after the heat wave treatments. End of season yield measurements will be taken.
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Oh, M., Wang, X., Wu, X., Zhao, Y., Clouse, S.D., Huber, S.C. 2010. Phosphorylation of Tyr-610 in the receptor kinase BAK1 plays a role in Brassinosteroid signaling and basal defense gene expression. Proceedings of the National Academy of Sciences. 107(4):17827-17832.
Drewry, D.T., Kumar, P., Long, S., Bernacchi, C.J., Liang, X., Sivapalan, M. 2010. Ecohydrological responses of dense canopies to environmental variability Part 1: Interplay between vertical structure and photosynthetic pathway. Journal of Geophysical Research-Biogeosciences. doi:10.1029/2010JG001340.
Gillespie, K.M., Rogers, A., Ainsworth, E.A. 2011. Growth at elevated ozone or elevated carbon dioxide concentration alters antioxidant capacity and response to acute oxidative stress in soybean (Glycine max). Journal of Experimental Botany. 62(8):2667-2678.
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