ABSTRACT: A reporter gene was constructed consisting of the 5´ region of the C. reinhardtii rbcL gene from position –70 to +47, relative to the transcription start point, fused to the E. coli uidA(GUS) structural gene terminated by the Chlamydomonas psaB 3´ end. Two point mutations were introduced into this construct at positions +46 and +47 (A to T and C to T, respectively) in the rbcL 5´UTR. The construct was introduced into the Chlamydomonas chloroplast genome downstream of the atpB gene. Transcript accumulation from this reporter gene was determined by a Northern blot assay. It was found that GUS transcripts did not accumulate.