Analysis of the 5' cis-regulatory region of the seed storage protein gene helianthinin : a promoter proximal region confers regionalized seed-specific expression

Vita.DNA elements involved in the tissue-specific expression of two sunflower helianthinin genes were identified by analysis of B-glucuronidase (GUS) expression in transgenic tobacco driven by sequences derived from the 5' upstream regions of these genes. All members of a series of 5' deletions expressed GUS in a seed-specific manner. A promoter proximal region (PPR) was identified that conferred significant GUS expression in seeds but not in leaves of transgenic tobacco. This promoter proximal region was also shown to be dominant to an abcisic acid (ABA) responsive element and an A/T rich region with respect to tissue-specific expression. Both of these elements affected the developmental profile of PPR driven GUS expression in transgenic tobacco seeds. Histochemical localization of GUS in the 5' deletions series and other chimeric promoters indicates that the helianthinin 5' cis-regulatory region can be divided into spatial domains within the embryo. The PPR corresponds to the cotyledon/apical shoot region although enhancement of PPR expression indicated that the PPR is capable of driving expression further down the embryo axis. Additional elements alter the dynamic range of expression and interactions between elements is more complex than a simple additive effect of linear elements