Promoter analysis of a light‐regulated gene encoding hydroxypyruvate reductase, an enzyme of the photorespiratory glycolate pathway

Abstract

SummaryHydroxypyruvate reductase (HPR) is a peroxisomal enzyme that catalyzes the NADH‐dependent reduction of hydroxypyruvate to glycerate in the photorespiratory glycolate pathway. HPR gene expression in cucumber seedlings is organ‐specific and light‐regulated. A 5.7 kb fragment of cucumber genomic DNA containing the entire HPR‐encoding gene, hpr‐A, plus 1069 bp OF 5′ flanking sequence was introduced into tobacco, as was a construct consisting of the upstream region (positions ‐ 1069 to +43) of the hpr‐A gene fused to the ß‐glucoronidase (GUS) reporter gene. Both constructs were expressed in the transgenic plants in an organspecific and light‐dependent manner. A deletion analysis of the 5’flanking sequence of the hpr‐A gene was conducted in transgenic tobacco. A construct in which the 5′‐flanking region had been deleted to within 299 bases of the transcription start site was sufficient to confer a high level of light‐regulated expression on the hpr‐A gene in the transgenic plants. However, deletion to position ‐218 resulted in a substantial reduction in expression. The region between positions ‐299 and ‐218 contains sequences resembling the 1 box and G box elements that are associated with other light‐regulated genes.