DIFFERENTIAL EXPRESSION OF CATALASE GENES IN NICOTIANA-PLUMBAGINIFOLIA (L)

We have analyzed the expression of three catalase (Cat; EC 1.11.1.6) g enes from Nicotiana plumbaginifolia by means of RNA blot and in situ h ybridizations. Our data demonstrate that the expression of each catala se is associated with a particular H2O2-producing process. Cat1 appear s to be specifically involved in the scavenging of photorespiratory H2 O2 and is under control of a circadian rhythm, Cat2 is uniformly expre ssed in different organs with a cellular preference for vascular tissu es, and the expression profile of Cat3 points to a role in glyoxysomal processes. Differential expression of these catalases is also manifes ted in response to temperature changes. DNA sequence comparison with o ther dicotyledonous catalases led to the identification of at least th ree distinct classes, which indicates that the functional organization of catalases is generally conserved in dicotyledonous plants.