Sequence and expression characteristics of three G-box-binding factor cDNAs from Brassica napus [corrected]

G-box-binding factors (GBFs) are bZIP proteins that have been implicated in the transcriptional control of a number of plant genes including the family for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. Using rbcS promoter regions as recognition site probes, we have cloned three Brassica GBFs designated as BnGBF1a, 1b and 2a. RNA gel blot analyses showed that all three BnGBF sequences give transcripts of the same size (1.3 kb) but in different amounts at a constant ratio in various tissues and developmental stages (1a > 2a > 1b). Transcript pools were largest in photosynthetically active organs such as leaves and cotyledons. Pool sizes correlated with those of total rbcS transcripts.