THE VICIA FABA DIAMINE OXIDASE SYSTEM AND ITS ROLE IN RESPONSE TO ASCOCHYTA FABAE AND TO WOUNDING

Abstract

Diamine oxidase (DAO) activity was determined in internodes and leaves of faba bean (Vicia faba L.) cultivars susceptible and resistant to Ascochyta blight. DAO activity was measured in stems and leaves of whole plants and on detached leaves, untreated or inoculated with a highly virulent Ascochyta fabae isolate. DAO activity was higher in leaves than in stems, and decreased acropetally along the plant. No increase in activity was detected as a response to inoculation. The time course of DAO activity was analysed during A. fabae infection of the third leaf of V. faba seedlings. In fact, DAO activity with different inoculum concentrations showed no significant differences between inoculated plants and controls. Moreover, no increase was detected either in the susceptible line 14-12 or in the resistant line 29H. The time courses of DAO activity was also analysed during wound healing of the third internodes and leaves of the faba bean cultivar ‘Lunga delle Cascine’ and line 29H. Enzyme activity was enhanced during the days following wounding, showing that this enzyme may have an important role in tissue repair.