The promoter of coconut foliar decay-associated circular single-stranded DNA directs phloem-specific reporter gene expression in transgenic tobacco.
A full-length double-stranded DNA copy of the single-stranded circular DNA associated with coconut foliar decay virus (CFDV) was constructed. Full-length CFDV DNA and smaller fragments were transcriptionally fused to the β-glucuronidase reporter gene and examined for promoter activity in vivo. In stably transformed tobacco plants, the CFDV DNA promoter conferred a tissue-specific expression pattern in that the reporter gene was specifically expressed in the phloem tissue of the vascular system in stems, leaves and flowers. These results are in agreement with the previously reported association of CFDV DNA with the phloem of its coconut host plant.