BIOCHEMICAL AND HISTOCHEMICAL LIGNIN DETERMINATION AND RELATED ISOPEROXIDASES IN PEACH FRUIT ENDOCARP

A correlation among lignin content, its histochemical detection and is operoxidases related with peach endocarp lignification during stage II of fruit growth development, is performed in this work. These studies will clear aspects of peach ripening and its relationship with specif ic isoperoxidases. A peak of total peroxidase activity was found for p roteins ionically bound to endocarp cell walls in day 64 after anthesi s. This was the first day in which lignin was detected both chemically and histochemically. A group of these ionically bound isoperoxidases was partially purified through a SP-Sephadex column. Among these, the cationic isoforms showed the highest activity in the oxidation of coni feryl alcohol, a monolignol precursor of lignin biosynthesis. This fac t suggests that basic isoperoxidases are mainly involved in this proce ss. The most important finding was that coniferyl alcohol oxidase acti vity was temporally correlated with active lignification of endocarp.