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United States Department of Agriculture

Agricultural Research Service

Research Project: Optimizing Rubisco Regulation for Increased Photosynthetic Performance Under Climate Change

Location: Plant Physiology and Genetics Research

2010 Annual Report

1a. Objectives (from AD-416)
The objective of this proposal is to develop the technology for improving the efficiency of Rubisco, particularly under the warmer temperatures predicted from climate change. To resolve some of the basic scientific questions that are impeding wide-spread implementation of the technology, we propose to move beyond Arabidopsis by using the oilseed plant, Camelina sativa, to refine the technology and then evaluate the results of the refinements under more natural conditions. The research will allow us to evaluate several mechanistic questions, while also improving camelina germplasm.

1b. Approach (from AD-416)
To test the feasibility of improving photosynthetic thermotolerance, we would like to launch an extensive transgenic project with the oilseed crop, camelina. In this project we would express both regulated and non-regulated forms of modified activase behind activase and heat-inducible promoters in a background of wild type activase. Transgenic camelina plants harboring the various constructs will be evaluated under natural conditions of light under control and elevated temperatures in the greenhouse and plants with superior performance will be tested in the field. Successful completion of the three objectives with camelina and a fourth objective with tobacco will resolve outstanding questions about the feasibility of improving plant thermotolerance by introducing an improved activase and answer several basic mechanistic questions about the regulation of Rubisco in plants.

3. Progress Report
This subordinate project is related to parent project Subobjective 1A: “Improve crop tolerance to heat stress by devising approaches to improve the ability of Rubisco activase to activate Rubisco at leaf temperatures above the optimum for photosynthesis.” The ADODR monitored progress of this agreement by direct supervision of the scientist supported by this grant. The project was initiated in May, 2010. The thermotolerance of photosynthesis in camelina was determined in both the field and in growth chambers. Photosynthesis was sensitive to inhibition by moderate heat stress. Experiments are being initiated to relate the results to the effect on Rubisco activation. To determine the mechanism for regulation of Rubisco activase in plant species that express only the non-redox regulated beta-isoform, the tobacco Rubisco activase gene was modified by addition of a redox-regulated C-terminal extension to produce an artificial tobacco alpha-isoform of Rubisco activase. The modified gene was expressed in E.coli. Experiments have been initiated to examine the properties of the recombinant artificial alpha activase and to transform tobacco plants with the modified gene. The research on improving plant thermotolerance using camelina relates directly to Component 4 of the Action Plan for NP301: Plant Biological and Molecular Processes and specifically to Problem Statement 4B: Biological Processes that Improve Crop Productivity and Quality.

4. Accomplishments

Last Modified: 10/16/2017
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