Transient expression of green fluorescent protein in various plastid types following microprojectile bombardment

The green fluorescent protein gene (gfp) is a widely used reporter in both animals and plants. Fusions between the plastid rrn promoter or the Escherichia coli trc promoter and the gfp coding region have been delivered to chloroplasts using gold or tungsten microprojectiles, and fluorescence from GFP was visible in individual tobacco chloroplasts and in the abnormally large chloroplasts of the arc6 mutant of Arabidopsis thaliana 2-4 days after bombardment. The fusion of the gfp coding region to the bacterial trc promoter demonstrated that a bacterial promoter is active in chloroplasts in vivo. GFP was also detectable in amyloplasts of potato tubers and in chromoplasts of marigold petals, carrot roots and pepper fruits 4 days after bombardment. This demonstrates that GFP can be used as a reporter for transient gene expression in chloroplasts and in non-photosynthetic plastids in a range of higher plants.