Transcriptional activation of the parsley chalcone synthase promoter in heterologous pea and yeast systems

Introduction by electroporation of different parsley (Petroselinum crispum) CHS-promoter/beta-glucuronidase(GUS)-reporter constructs into pea (Pisum s ativum L.) protoplasts leads to a high constitutive GUS-expression and to t he loss of the light-inducibility seen in the homologous parsley protoplast system. These results indicate that Unit 1 of the parsley CHS-promoter is only partly responsible for the GUS-expression detected. Instead, additiona l cis-elements, which are located downstream within 100 bp from the transcr iptional start site, mediate the de-repression in pea protoplasts. In contr ast, in yeast (Saccharomyces cerevisiae) cells, the GUS expression from the heterologous CHS/GUS construct is controlled by elements between Unit 1 an d -100 bp. In both pea and yeast cells, transcription factors different fro m those regulating UV-responsiveness in parsley, are probably mediating the constitutive expression from the heterologous construct. The results with pea protoplasts imply that protoplastation of pea leaf cells itself induces de-repression as a result of stress to the protoplasts. This notion was st rengthened by the finding that mRNA levels of the endogenous chalcone synth ase were drastically increased as the result of the protoplastation procedu re. (C) 1999 Editions scientifiques et medicales Elsevier SAS.