The root nodule is a highly differentiated organ where bacterial nitrogen fixation takes place. NMHC5 and NMH7, two putative transcription factors of the MADS-box family are thought to be involved in the regulation of alfalfa nodule differentiation.
The DNA-binding ability of NMHC5 and NMH7 was investigated using mobility shift assays. NMHC5 was found to bind a specific DNA sequence as a homodimer. NMH7 was unable to interact with DNA in vitro, which is consistent with its secondary structure and predictions of heterodimeric binding. The second part of this study describes the isolation and sequence analysis of two related genes ngl-6 and ngl-9, encoding potential heterodimer partners for NMH7.
