Identification of tissue-specific, dehydration-responsive elements in the Trg-31 promoter

Trg-31 is a pea gene which is rapidly induced in response to dehydration stress. Trg-31 belongs to a family of membrane intrinsic proteins that play a role in facilitating inter-membrane transport. In order to understand the mechanism of regulation of Trg-31 expression we defined the cis-acting elements of the Trg-31 promoter and the trans-acting factors that interact with them. Deletion analysis of the Trg-31 promoter in transgenic tobacco plants indicated the presence of two positive regulatory region: (1) between the -1412 to -1066 nucleotides and (2) between the -559 to -391 nucleotides, with respect to the transcription initiation site. A negative regulatory element was also identified between -1066 and -559 nucleotides. All three regulatory regions specifically regulated Trg-31 induction in leaf tissue and had little or no effect on Trg-31 induction in root tissue. Gel-mobility shift assays indicated the presence of leaf nuclear proteins that interacted with the -1412 to -1066 and -1066 to -559 regions and an 'ABRE-like' sequence at -74 in the 5' promoter region of Trg-31.