TRANSIENT EXPRESSION OF THE GUS REPORTER GENE IN THE PROTOPLASTS AND PARTIALLY DIGESTED CELLS OF ULVA-LACTUCA L (CHLOROPHYTA)

The electroporation-mediated DNA transfer and expression of the gene e ncoding beta-glucuronidase (GUS) in the protoplasts and partially dige sted cells of a marine green alga Ulva lactuca was studied. In order t o obtain protoplasts, vegetative blades of freshly collected plants we re digested with a mixture of 1.5% Cellulysin and 1.5% abalone acetone powder for 3 h. Protoplasts were separated from partially digested th alli by sieving and centrifugation. The GUS reporter gene carried on t he plasmid pBI121 was introduced into both isolated protoplasts and pa rtially digested cells by electroporation in the presence of polyethyl ene glycol (PEG-8000). Different parameters of electroporation were va ried in order to achieve 50% viability of the protoplasts. Histochemic al assays revealed a transient expression of GUS activity in both elec troporated protoplasts and partially digested cells 2 to 7 days after electroporation, indicating that an exogenous gene can be introduced i nto the protoplasm with or without the removal of the cell wall. Subse quent culture led to the regeneration of protoplasts into filamentous or disc-like multicellular plantlets. However, none of these regenerat ed plants stained positively for GUS activity.