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United States Department of Agriculture

Agricultural Research Service

Title: Molecular Control of Carbon-Nitrogen Interactions in Symbiotic Nitrogen Fixation

Authors
item Vance, Carroll
item Litjens, R - FONTYS UNIVERSITY
item Schulze, J - MARTIN LUTHER UNIV
item Bucciarelli, B - UNIVERSITY OF MINNESOTA
item Trepp, G - ETH ZURICH
item Samac, Deborah
item Allan, D - UNIVERSITY OF MINNESOTA
item Tesfaye, M - UNIVERSITY OF MINNESOTA

Submitted to: International Congress on Plant Nutrition Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 1, 2001
Publication Date: N/A

Technical Abstract: Malate plays a key role in symbiotic nitrogen fixation by providing the substrate for bacteroid respiration, thus fueling nitrogenase, and by providing the carbon skeletons for assimilation of fixed nitrogen. Malate may also play a role in regulating the nodule variable oxygen diffusion barrier. To define genetic and biochemical regulation of root nodule malate eformation, we isolated the alfalfa genes encoding cytosolic and nodule enhanced malate dehydrogenase (MDH: EC 1.1.1.82). Protein and mRNA localization showed that nodule enhanced MDH was localized predominantly in plastids of infected cells while cytosolic MDH occurred primarily in uninfected cells. Localization of these enzymes in distinct cell types of root nodules may differentiate function for symbiotic nitrogen fixation. Initial studies suggest over-expression of nodule enhanced MDH in alfalfa may enhance nitrogen fixation.

Last Modified: 4/23/2014
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