ABSTRACT
This chapter reviews protection from oxidative stress present in the leaves of trees and evaluate their role in preventing photooxidative damage. The glutathione content in leaves of deciduous tree species has only rarely been investigated. Little information is available with respect to the characteristics and subcellular localization of protective enzymes in leaves of tree species. Tree species at high altitude are exposed to higher irradiation, lower average temperatures, and higher mean ozone concentrations than trees grown at valley level. Tree species may encounter specific problems as compared to annual species, since they must cope with large changes in environmental conditions in their long life-span. To date, most studies conducted with trees present only circumstantial evidence for an association between levels of protective systems, environmental changes, and damage symptoms. Therefore, investigations are needed to determine whether stress tolerance in susceptible tree species can be enhanced by increasing their antioxidative capacity.
