Molecular cloning, characterisation and expression of two catalase genes from peach

Two cDNA clones encoding catalase (Cat1 and Cat2) from peach [Prunus persica (L.) Batsch] were identified, that show homologies to other plant catalases. The nucleotide sequences of the two coding regions showed 88% identity to each other. The amino acid sequences predicted from the two full-length clones showed the highest homology to a catalase from cotton and Nicotiana plumbaginifolia L. and included C-terminal tri-peptides typical of those used to target proteins to peroxisomes. Southern hybridisation analysis suggested the existence of two catalase genes in peach. The expression of Cat1 and Cat2 was determined in seeds, vegetative tissue, leaves during the seasonal cycle and in leaves in response to light / dark treatments. Cat1 had high levels of expression only in leaf tissue and was responsive to light and seasonal changes. Cat2 had high levels of expression in in vitro shoots and was also responsive to seasonal changes, but not to light. In situ hybridisations to leaf tissue indicated that the expression of Cat1 was localised mainly in palisade cells, while Cat2 mRNA was present in the vascular tissue. The results of the expression analysis and in situ hybridisation suggest a role for Cat1 in photorespiration and for Cat2 in stress responses.