9305007 Dunn Floral homeotic genes from Arabidopsis thaliana and Antirrhinum majus have been shown to share considerable sequence similarity with transcription factors from yeast (MCM1) and humans (SRF). all of these putative transcription factors contain a highly conserved DNA binding domain called the MADS box and are responsible for transducing environmental signals influencing organ development. To address the possibility that a member of this class of transcriptional regulators may be active in alfalfa root nodule development, degenerate oligonucleotides were designed to conserved sequences flanking the MADS box domain of the Arabidopsis thaliana ap3 homeotic gene. Preliminary data suggests that alfalfa root nodules express a MADS box gene localized primarily in the infected cells of the nodule. This factor is likely to play a role in both receiving signals originating from the bacteria and in transmitting the environmental cue to a cellular response. The first part of this project characterizes the alfalfa MADS box gene and examines its expression in several tissues. The second part of the project addresses questions about the function of this gene. The alfalfa MADS box domain will be inserted in place of the homologous region of the MCM1 deletion. The target genes of the alfalfa MADS box protein will be investigated by examining its specific binding to nodule specific plant promoters. The information produced from this study will be used to further examine the interaction of the MADS box protein with both plant promoters as well as bacterial factors required to bring about the desired symbiotic response. ***
