[Isolation, sequencing analysis and characterization of the promoter of banana lectin gene].

Banana (Musa spp) is one of the most important fruit crops in the world. Banana fruit is an ideal organ for producing foreign pharmaceutical proteins and chemicals by genetic engineering. A perfect promoter driving foreign gene to express strongly and specifically in banana fruit is necessary for that. In order to isolate a banana fruit-specific expressed promoter, a fragment of 702 nt nucleotide sequence upstream 5' of banana lectin (BanLec) gene, which was demonstrated to express specifically in banana fruit previously, was isolated by using chromosomal walking in this study. Bioinformatical analysis of this sequence shows that the sequence contains some typical elements of a promoter. To identify the fruit-specific expression of this promoter, a construct was derived from pBI121, which originally CaMV 35S promoter was replaced by the 702 nt nucleotide sequence, and named as pBIL2. Transformations of pBIL2 to roots, leaves and fruit pieces of banana were carried out by using particle bombardment. The transient expression of gus showed that the gus expressed specifically in banana fruit with a little higher level compared with CaMV 35S. It is the first report that BanLec promoter is a potential fruit-specific expressed promoter which can further be used in transgenes into banana.