Catalase and Manganese Superoxide dismutase are differentially expressed during development in woody species

Catalase (CAT) and superoxide dismutase (SOD), two of the major antioxidant enzyme systems, were examined by native PAGE in different tissues of germinating seed, adult tree and microcuttings of cypress, three different pine species and oak. Somatic and zygotic embryogenesis of horse chestnut was also analysed. In all the species Cat and SOD resulted differently active in the various tissues analysed. Catalase isoforms activity in particular resulted correlated with leaf growth in all the species analysed and in the case of cypress also with the tree age. During both zygotic and somatic embryogenesis analysis revealed remarkable differences in the CAT and SOD isoenzyme patterns. In contrast to zygotic, the CAT isoforms are equally active during the somatic embryo development. The SOD isoenzymes, one Mn-SOD and five Cu/Zn-SODs, were present during all the stages of zygotic embryo formation, but only the Mn-SOD and an Fe-SOD were detected during somatic embryogenesis. These data suggest the occurrence of oxidative stress conditions during in vitro culture. The results obtained indicate CAT isoenzymes are sensitive markers for leaf development and growth and their use to identify the phase state of the tree deserve to be further investigated. SOD, on the other hand, are convenient markers to monitor the occurrence of oxidative stress conditions during in vitro culture which could account for the difficulties observed in the development of the somatic embryo or rooting ability.