Promoters derived from banana bunchy top virus DNA-1 to-5 direct vascular-associated expression in transgenic banana (Musa spp.)

The intergenic regions of banana bunchy top virus (BBTV) DNA-1 to -5 were f used to the green fluorescent protein (GFP) and uidA reporter genes and ass essed for promoter activity in transgenic banana (Musa spp. cv. Bluggoe). P romoter activity associated with the BBTV-derived promoters was transgene d ependent with greatest activity observed using the GFP reporter. The BBTV p romoters (BT1 to BT5) directed expression primarily in vascular-associated cells, although levels of activity varied between individual promoters. Pro moters BT4 and BT5 directed the highest levels of GFP expression, while act ivity from BT1, BT2 and BT3 promoters was considerably weaker. Intron-media ted enhancement. using the maize polyubiquitin 1 (ubi1) intron, generated a significant increase in GUS expression directed by the BBTV promoters in t ransgenic plants.