Background: Antisense transcription is a widespread phenomenon in plants and mammals. Our previous data on rice gene expression analysis by microarray indicated that the sense and antisense transcripts at the OsDof12 locus were co-expressed in leaves. In current study, we analyzed the expression patterns in detail and looked for the possible mechanism related to their expression patterns.
Results: OsDof12, being a single copy gene located on rice chromosome 3, encodes a predicted Dof protein of 440 amino acids with one intron of 945 bp. The antisense transcript, OsDofl2os, overlaps with both the exonic and intronic regions of OsDof12 and encodes a functionally unknown protein of 104 amino acids with no intron. The sense-antisense OsDof12 transcripts were co-expressed within the same tissues, and their expressions were not tissue-specific in general. At different developmental stages in rice, the OsDof12 and OsDof12os transcripts exhibited reciprocal expression patterns. Interestingly, the expression of both genes was significantly induced under drought treatment, and inhibited by dark treatment. In the ProOsDof12-GUS and ProOsDof12os-GUS transgenic rice plants, the expression profiles of GUS were consistent with those of the OsDof12 and OsDof12os transcripts, respectively. In addition, the analysis of cis-regulatory elements indicated that either of the two promoters contained 74 classes of cis-regulatory elements predicted, of which the two promoter regions shared 53 classes.
Conclusion: Based on the expression profiles of OsDof12 and OsDof12os, the expression patterns of GUS in the ProOsDof12-GUS and ProOsDof12os-GUS transgenic rice plants and the predicted common cis-regulatory elements shared by the two promoters, we suggest that the co-expression patterns of OsDof12 and OsDof12os might be attributed to the basically common nature of the two promoters.