Transient expression of the gfp gene in tobacco leaves. A. Relative GFP mRNA level. B. Relative amount of GFP expressed. C. Specific GFP amount/unit mRNA of GFP. Average GFP level of three leaves for each construct divided by its corresponding mRNA level. G1-1(A) contained the Arabidopsis actin7 gene and its 5′-UTR intron (540 bp) instead of the Gladiolus 5′-UTR intron.