MOLECULAR RESPONSES TO ABSCISIC-ACID AND STRESS ARE CONSERVED BETWEENMOSS AND CEREALS

Promoter elements from the wheat Em gene have been characterized. Thes e elements are inducible by abscisic acid (ABA) and by osmotic stress. In this study, we demonstrated that the same promoter elements functi on in a distantly related plant species, the moss Physcomitrella paten s. Transient and stable expression of the beta-glucuronidase reporter gene was used to determine that the heterologous wheat promoter also r esponds to osmotic stress and ABA in moss. Mutational analysis of the promoter indicated that the mechanism of gene regulation is conserved in both species. Gel retardation and DNase I footprint analyses were c onducted to characterize further the interaction of moss transcription factors with the Em promoter. In addition, the synthesis of stress-re lated polypeptides in moss was observed. The evolutionary significance of these data and the potential for studying the entire ABA perceptio n-response pathway in moss are discussed.