Differential expression of invertase genes in internal and external phloem tissues of potato (Solanum tuberosum L.).

The cloning of promoter sequences of two invertase genes from potato (Solanum tuberosum L.) is described. Histochemical analysis of series of reporter transgenic lines reveals phloem-specific expression from both promoters, with one expressed preferentially in internal phloem and the other in external phloem of stem vascular bundles.