Characterization of the 11S Globulin Gene Family in the Castor Plant Ricinus communis L.

The 11S globulin (legumin) gene family has been characterized in the castor plant Ricinus communis L. Phylogenetic analysis reveals the presence of two diverged subfamilies (RcLEG1 and RcLEG2) comprising a total of nine genes and two putative pseudogenes. The expression of castor legumin genes has been studied, indicating that it is seed specific and developmentally regulated, with a maximum at the stage when cellular endosperm reaches its full expansion (around 40-45 DAP). However, conspicuous differences are appreciated in the expression timing of individual genes. A characterization of the 5'-proximal regulatory regions for two genes, RcLEG1-1 and RcLEG2-1, representative of the two legumin subfamilies, has also been performed by fusion to the GUS reporter gene. The results obtained from heterologous expression in tobacco and transient expression in castor, indicating seed-specific regulation, support the possible utility of these promoters for biotechnological purposes.