PROTEINS FUNCTIONALLY AND IMMUNOGENICALLY RELATED TO PATHOGENESIS-RELATED PROTEINS ARE INDUCED DURING PARSLEY LEAF SENESCENCE

The advancement of leaf senescence is accompanied by a reduction in ce llular protein content together with the induction of specific protein s which are probably involved in the process. In the present study, wi th parsley, we followed the changes in the levels of proteins function ally and immunogenically related to pathogenesis-related proteins duri ng both senescence of detached leaves and natural senescence of attach ed leaves. Both chitinase activity and protein level were found to be induced during senescence, as was the level of two other proteins immu nologically related to beta-1,3-glucanase and P4 pathogenesis-related proteins of citrus and tomato, respectively. A high correlation betwee n the advancement of senescence and the induction of these proteins wa s demonstrated. Treatments with CO2 or gibberellic acid, which retard senescence, reduced both chitinase activity and the level of the patho genesis-related proteins, whereas enhancement of senescence with ethyl ene induced them further. The induction of pathogenesis-related protei ns during senescence suggests that these proteins may have a primary r ole in this process.