A wheat α‐Amy2 promoter is regulated by gibberellin in transformed oat aleurone protoplasts

Gibberellin (GA 3 )‐responsive aleurone protoplasts isolated from Avena sativa have been successfully used as a transient expression system to analyse promoter fusions between the wheat α‐amylase gene α‐ Amy2/54 and the reporter gene GUS . Following PEG‐mediated uptake of plasmid DNA, transient expression directed by the α‐ Amy2/54 promoter was found to be regulated in the same way as the endogenous oat α‐amylase genes. Expression was thus dependent on the inclusion of GA 3 in the protoplast incubation media, could not be detected before a lag phase of 2 days following transformation and was inhibited by simultaneous addition of abscisic acid (ABA) with GA 3 to the media. In contrast, expression from the CaMV 35S promoter in the same system was not affected by GA 3 or ABA and could be detected 1 day after transformation. Introduction of a further three different promoters into the aleurone protoplasts confirmed that GA 3 specifically controlled transient expression from the α‐ Amy2/54 promoter only. Promoter deletions of the α‐ Amy2/54 : GUS fusion demonstrated that sequences within 300 bp of the start of transcription of the gene were sufficient to direct high‐level expression that was regulated by GA 3 and ABA.