Arabidopsis thaliana endo-1,4-β-glucanase (cel1) promoter mediates uidA expression in elongating tissues of aspen (Populus tremula)

Transgenic aspen plants were transformed with a bacterial β-glucuronidase gene (uidA) under the control of the Arabidopsis thaliana elongation-specific endo-1,4-β-glucanase (cel1) promoter. Transformed plants exhibited a high level of β-glucuronidase (GUS) activity in young, fast-growing tissues. Unlike the cauliflower mosaique virus 35S promoter, the expression pattern of uidA in the shoots and leaves was dear-cut and highly controlled by cel1 promoter. GUS-staining in the leaves mirrored the pattern of expanding cells in the organ. These results further substantiate the link between cel1 expression and plant cell elongation. Moreover, our results suggest that the cell promoter may be useful in the genetic engineering of forest trees and possibly other plants when gene expression is desired only in fast growing tissues.