Actin genes with unusual organization in the parasitic angiosperm Striga asiatica L. (Kuntze).

In order to better understand the regulation of cellular differentiation during haustorial development in parasitic angiosperms, we have begun to examine the structure and expression characteristics of genes encoding various components of the plant cytoskeleton in Striga asiatica L. (Kuntze). We describe here the cloning and characterization of three actin genes from Striga with significant similarity at the nucleotide level and encoding proteins having greater than 98% identity. However, the three genes (designated SAAc-1, SAAc-2 and SAAc-3) differ from each other in their organization and SAAc-3 contains an unusual exon-intron arrangement relative to genes encoding actins described in other higher plants. The significance of these observations concerning the evolutionary origins and potential roles of Striga actin genes is discussed.