Expression and promoter activity of the desiccation-specific Solanum tuberosum gene, StDS2

Environmental stresses induce the expression of several plant genes via multiple and cross-talking signalling pathways. Previously it was shown that ScDS2 , a gene of the wild potato species, Solanum chacoense , is highly inducible by dehydration but not by abscisic acid (ABA), the mediator of many plant stress responses. Herein it is shown that ScDS2 -related genes are present in the cultivated potato, Solanum tuberosum (StDS2) and also in the non-tuberizing Solanum species, Solanum brevidens (SbDS2). We show that expression of StDS2 is dehydration-specific, is not inducible by cold, heat, salt, hypoxia or oxidative stresses, and is independent of ABA. Signalling of StDS2 induction, however, is dependent on the synthesis of novel proteins because cycloheximide can block StDS2 expression. To analyse the promoter region of StDS2 a genomic library of Solanum tuberosum was established and 1140 and 498 bp regions of the StDS2 promoter were isolated. The promoter fragments were fused to the beta-glucuronidase (GUS) reporter gene and tested in transgenic potato plants. Both promoter fragments were able to induce GUS activity in response to dehydration. This result suggests that drought-specific cis -elements are located within 498 bp upstream to the StDS2 coding sequence.