Differential rind and pulp ripening of transgenic antisenseACC oxidase melon

1-Aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO) antisense Cantaloupe melons (Cucumis melo var. cantalupensis Naud.) unable to produce ethylene were used to identify the characteristic physiological processes occurring during ethylene-dependent ripening and to determine which tissue (pulp or rind) was most affected by this plant hormone. The antisense fruits were compared with untransformed fruits, which were used as controls. The most pronounced differences were observed in the rind when the untransformed melons entered in the climacteric respiratory stage. The major pigments, chlorophylls and carotenoids, remained undegraded, while sucrose and citric acid were accumulated continuously in antisense fruit rind. No big differences in the ripening parameters tested were observed in the pulp, except for those regarding the citric acid content and ripening index. The hypothesis of a differential ripening between pulp and rind in Cantaloupe melon is proposed.