CONSEQUENCES OF ALTERING RUBISCO REGULATION - USDA, ARS, Midwest Area Office

Recipient Organization
USDA, ARS, Midwest Area Office
1201 W. Gregory Drive
Urbana,IL 61801

Performing Department
(N/A)

Non Technical Summary
(N/A)

Animal Health Component

Research Effort Categories

Basic

100%

Applied

Developmental

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
203	1510	1000	10%
203	1510	1040	10%
203	1820	1000	25%
203	1820	1040	25%
203	2010	1000	10%
203	2010	1040	10%
203	2410	1040	10%

Knowledge Area
203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants;

Subject Of Investigation
1510 - Corn; 2010 - Sugar beet; 1820 - Soybean; 2410 - Cross-commodity research--multiple crops;

Field Of Science
1040 - Molecular biology; 1000 - Biochemistry and biophysics;

Goals / Objectives
The photosynthetic characteristics and growth under various environmental regimes will be determined for a series of transgenic Arabidopsis plants in which modified forms of Rubisco activase have been introduced to alter the regulation of Rubisco. The properties of these plants should indicate the significance of Rubisco regulation as a determinant of plant productivity and in the response of plants to their environment.

Project Methods
The physiological consequences of altering the activity and other kinetic properties of a regulatory protein such as Rubisco activase cannot always be predicted on the basis of in vitro experiments with the isolated proteins. A detailed examination of plants transformed with altered Rubisco activase proteins in necessary to verify ultimately any conclusions drawn from in vitro studies and the study of such plants can address questions that cannot be approached in any other way and is likely to raise new questions. Thus evaluation to the properties of such transformed plants are likely to provide new insights into the regulatory process. Urbana, IL, BSL-1; Certified September 9, 2001 through life of agreement.

Progress 09/30/00 to 09/29/05

Outputs
4d Progress report. This report serves to document research conducted under an Interagency Reimburseable Agreement between ARS and the US Department of Energy. Additional details of the research can be found in the report for the parnt project 3611-21000-013-00D, Identifying and Manipulating Determinants of Photosynthate Production and Partitioning. The research is determining the impact of altering the regulation of a key photosynthetic enzyme on photosynthate production under diverse environmental conditions, which is one of the goals of the parent project. This years progress included a kinetic characterization of the rate of decline in the activity of maximally activated Rubisco (requiring high CO2 and Mg2+) which is facilitated by high temperature, low concentration of CO2 or Mg2+ and high CO2. Because Rubisco activity must be maintained by the activity of Rubisco activase, this information provides a baseline for understanding and resolving the effects of high temperature on Rubisco and Rubisco activase activity under the physiologically relevant conditions of non-saturating CO2 and Mg2+ concentrations.

Impacts
(N/A)

Publications

Progress 10/01/03 to 09/30/04

Outputs
4. What were the most significant accomplishments this past year? This report serves to document research conducted under an Interagency Reimbursable Agreement between ARS and the U.S. Department of Energy. Additional details of the research can be found in the report for the parent research project #3611-21000-013-00D, Identifying and Manipulating Determinants of Photosynthate Production and Partitioning. The research is determining the impact of altering the regulation of a key photosynthetic enzyme on photosynthate production under diverse environmental conditions, which is one of the goals of the parent project. This year's progress included the discovery that wild type Rubiscos from bacteria, algae and plants produce significant amounts of hydrogen peroxide as a minor product associated with the oxygenase activity of Rubisco. The other product of the reaction is a known potent inhibitor of Rubisco and thus this reaction contributes to the slow decline in Rubisco activity in the absence of Rubisco activase activity.

Impacts
(N/A)

Publications