Genomic Structure and Promoter Analysis of Phosphoenolpyruvate Carboxylase in a C3 Plant, Nicotiana sylvestris

Three genes encoding phosphoenolpyruvate carboxylase were isolated from Nicotiana sylvestrisand designated Nsppc1-3. Sequencing of nucleotides showed that the coding sequence and deduced amino acid sequences were highly conserved among the genes, but sequences for noncoding regions including introns and 5′-flanking regions were not conserved. Analysis of the transcript level of the genes by a combination of reverse transcriptase-PCR and restriction fragment polymorphism showed mostNsppc1in the leaves, stems, roots, and cultured cells of N. sylvestris. β-Glucuronidase activity was detected histochemically in mesophyll cells in leaves, lateral buds, and vascular bundles in roots of transgenic tobacco harboring a chimeric construct of the Nsppc1promoter and the gene for β-glucuronidase. Deletion analysis indicated the presence of a silencer-like element for basal expression in the promoter region of Nsppc1.