A 69 bp fragment in the pyrroline-5-carboxylate reductase promoter of Arabidopsis thaliana activates minimal CaMV 35S promoter in a tissue-specific manner

The Arabidopsis thaliana gene that encodes pyrroline-5-carboxylate reductas e (At-PSR), the last enzyme in proline biosynthesis in A. thaliana, is deve lopmentally regulated and is highly expressed in cells that divide rapidly or undergo changes in osmotic potential. A 69 bp region (P69; -120 to -51) has previously been identified in a 5' deletion analysis of the At-PSR prom oter to be necessary for the basal expression. Here, the essential role of P69 for tissue-specific expression of At-PSR is demonstrated by loss- and g ain-of-function experiments. (C) 1999 Federation of European Biochemical So cieties.