Expression pattern of ara12, an Arabidopsis homologue of the nodule-specific actinorhizal subtilases cg12/ag12

In response to infection by Frankia, cells of Alnus glutinosa and Casuarina glauca nodules strongly express a subtilase-gene (ag12 and cg12 respectively). In order to gain a better understanding of the function of these genes in the symbiotic process, we have analysed the gene expression of ara12, an Arabidopsis thaliana homologue of cg12 and ag12. Transcription fusion of the promoter region of ara12 to the β-glucuronidase gene was introduced into A. thaliana. Para12-gus expression was found in young developing tissues. This result suggests that ara12 might be involved in proteins or polypeptides processing during A. thaliana development. We therefore speculate that cg12 and ag12, the actinorhizal homologues of ara12 might be involved in differentiation of Frankia infected cells in nodules.