Characterization of a Casuarina glauca nodule-specific subtilisin-like protease gene, a homolog of Alnus glutinosa ag12

In search of plant genes expressed during early interactions between Casuar ina glauca and Frankia, we have isolated and characterized a C, glauca gene that has strong homology to subtilisin-like protease gene families of seve ral plants including the actinorhizal nodulin gene ag12 of another actinorh izal plant, Alnus glutinosa, Based on the expression pattern of cg12 in the course of nodule development, it represents an early actinorhizal nodulin gene. Our results suggest that subtilisin-like proteases may be a common el ement in the process of infection of plant cells by Frankia in both Betulac eae (Alnus glutinosa) and Casuarinaceae (Casuarina glauca) symbioses.