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ngl9: A Third MADS Box Gene Expressed in Alfalfa Root Nodules

December 2001 , Volume 14 , Number  12
Pages  1,463 - 1,467

Joseph C. Zucchero , Michal Caspi , and Kathleen Dunn

Department of Biology, Boston College, Chestnut Hill, MA 02467 U.S.A.

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Expression of MADS box genes has previously been localized to the infected cells of alfalfa (Medicago sativa) root nodules. These genes represent the first putative transcription factors to be identified in nodules and are hypothesized to be involved in a signal transduction pathway initiated by the intracellular bacterium. The eventual activation of specific target genes defines pertinent characteristics of this nitrogen-fixing differentiated cell. In this study, we identify a third nodule MADS box gene, ngl9, and demonstrate that the DNA-binding activity of its protein product is dependent on the presence of a second MADS box protein, NMH7. Despite previous results to the contrary, both genes are expressed in the early stages of flower development, further strengthening the premise that nodule developmental programming may capitalize upon existing developmental cascades.

© 2001 The American Phytopathological Society