Upstream sequence of fatty acyl-CoA reductase (FAR6) of Arabidopsis thaliana drives wound-inducible and stem-specific expression.

An Arabidopsis mutant line T90, exhibiting a stem-specific and wound-responsive GUS expression was identified from a population of Arabidopsis thaliana tagged with a promoterless β-glucuronidase (GUS) in the T-DNA. Sequence flanking the insertion from the right border was amplified by TAIL PCR and cloned. The insertion was located in the third chromosome, 57 bp upstream of the ATG start codon in 5' untranslated region (UTR) of the fatty acyl-CoA reductase 6 (FAR6) gene. RT-PCR analysis of the FAR6 gene revealed that the gene is expressed predominantly in stem tissue. Semi-quantitative RT-PCR showed that the expression is also induced by wounding in the epidermal layer of mature stem internodes. The transcription initiation site (TSS) was identified by 5' RACE PCR. Different 5' deletion fragments of the promoter sequences were developed and linked to the GUS reporter gene as transcriptional fusions and the expression patterns of GUS were histochemically analyzed in transgenic Arabidopsis plants. Sequences from -510 bp upstream to the transcriptional start site were sufficient to exhibit wound-inducible GUS expression in the stems. The addition of further upstream sequences (-510 to -958, -1,400 or -1,456) enhanced and extended the wound-inducible GUS expression throughout the mature stem.