A 318 bp
mannopine synthase 2' (mas2') promoter
element from the
T-DNA of Agrobacterium tumefacians can direct
wound-inducible and root-preferential expression of a linked uidA gene in transgenic tobacco plants.
Wound inducibility is further enhanced by
sucrose in the medium. Promoter deletion analysis indicated that the
sucrose enhancement is conferred by a region extending from -318 to -213.
DNase I footprinting indicated that an A/T-rich DNA sequence in this region is protected by tobacco nuclear factors. Regions extending from -103 to +66 and from -213 to -138 directed
wound-inducibile expression of a linked uidA gene when placed downstream of a CaMV 35S enhancer or upstream of a truncated (-209) CaMV 35S promoter, respectively.
DNase I footprinting analyses indicated that
proteins from wounded tobacco leaves specifically bound to three contiguous motifs downstream of the mas2' TATA box. In addition to a common retarded band formed by the upstream
wound-responsive
element complexed with
proteins from either wounded or unwounded tobacco leaves, two unique retarded bands were observed when this
element was incubated with
protein from wounded leaves. Methylation interference analysis additionally identified an unique motif composed of promoter elements and nuclear factors derived specifically from wounded tobacco leaves. We propose a model to describe the involvement of nuclear factors with mas2' promoter elements in
wound-inducible gene expression.