Features of the eGFP Gene Expression in Transplastomic Tobacco Plants

Transplastomic tobacco plants expressing a reporter gene egfp and selectable marker gene aadA as part of a bicistronic operon were obtained using the bioballistics method. Features of egfp gene expression were studied in two groups of transplastomic plants: seed progeny obtained from self-pollination and plants obtained as a result of two successive regeneration cycles from the leaves of the original transformants. A comparative fluorimetric analysis of the recombinant protein accumulation in groups of transplastomic plants and nuclear transformants was carried out. It was found that the amount of recombinant eGFP protein accumulated in the leaves of transplastomic plants was unexpectedly low and did not exceed the level established for nuclear transformants. Real-time PCR results showed that the low level of recombinant eGFP accumulation was not associated with low levels of transgene expression or the presence of nontransgenic copies of the plastid genome in chloroplasts. This is most likely due to limitations imposed at the level of translation of recombinant proteins in chloroplasts.