Transcription of a sorghum phosphoenolpyruvate carboxylase gene in transgenic tobacco leaves: maturation of monocot PRE-mRNA by dicot cells.

The expression of a Sorghum vulgäre gene encoding the phosphoenol-pyruvate carboxylase involved in C4 photosynthesis has been studied after introduction into tobacco. Northern blot analysis of poly(A) mRNA from green leaves demonstrated i) the efficiency of this monocot promoter, ii) the transcription of the sorghum phosphoenol-pyruvate carboxylase mRNA with the expected size (3.4kb). These results strongly suggested that introns of this monocot gene have been excised efficiently by the dicot cells. Moreover, the presence of the sorghum phosphoenol-pyruvate carboxylase mRNA was not detected in the roots of the transformed plants, suggesting that the 2.4kb 5'-region of the gene could be sufficient to confer the tissue specific expression.