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United States Department of Agriculture

Agricultural Research Service

Title: Evidence from Antisense and Inhibitor Studies Suggests a Role for Pepc in N2 Fixation?

Authors
item Schulze, Joachim - MARTIN LUTHER UNIV GERMAN
item Shi, Lifang - UNIVERSITY OF MINNESOTA
item Samac, Deborah
item Gantt, J - UNIVERSITY OF MINNESOTA
item Vance, Carroll

Submitted to: Nitrogen Fixation International Congress
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 1997
Publication Date: N/A

Technical Abstract: Two approaches were used to evaluate the role of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) in N2 fixation and N assimilation of alfalfa. Transgenic plants were generated containing an antisense cDNA construct of nodule PEPC driven by the nodule enhanced AAT-2 promoter. Compared to the transformed controls, 10 antisense PEPC plants show a clear rreduction in PEPC enzyme activity and protein (Western blot). This reduction ranged from 35 to 90% and was accompanied by a comparable decrease in PEPC mRNA. Individual antisense PEPC plants when clonally propagated were altered in viability. The second approach involved treating nodules with the PEPC competitive inhibitor, 3,3-dichloro-2- dihydroxyphosphinoylmethyl-2-propenoate (DCDP). In vitro DCDP inhibits PEPC but not other enzymes of N metabolism. Results from experiments comparing the impact of DCDP treatment versus antisense PEPC inhibition on N2 fixation, N assimilation, nodule CO2 fixation, amino acids, and organic acid labeling will be presented. Funding source Deutsche Akadamie der Naturforscher Lepoldina (J.S.) and NSF/IBN: 9206890.

Last Modified: 12/18/2014
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