Transient gene expression and influence of promoters on foreign gene expression in Arabidopsis thaliana

The influence of a variety of parameters was investigated on polyethylene glycol (PEG)-mediated transient nptII and gus gene expression in mesophyll protoplaats of Arabidopsis thaliana ecotype, Estland, in order to develop a suitable transient gene expression system. The investigation revealed that a combination of 20% PEG, incubation time of 15 min, 20-30 mu g plasmid concentration per mi along with 50 mu g carrier DNA m/l, and inclusion of calcium and magnesium ions during transfection followed by a culture period of 24 h registered maximum NPTII activity. Of the various promoters used fur driving expression of the gus gene, the ubiquitin promoter from A. thaliana was the most efficient followed by 35S promoter of the CaMV and the actin promoter of rice. For comparison, similar studies in protoplasts of rice, wheat, and Brassica also revealed the differences in strength of these promoters. Arabidopsis ubiquitin promoter was the most effective in Brassica, and the rice actin 1 promoter was the most effective in rice and wheat.