Cactus pear: a model to study fruit ripening

Development, maturation and ripening of fruits have received considerable experimental attention, primarily due to the uniqueness of such processes to plant species and the importance of these products as significant aspects of human dietary intake and nutrition. The semiarid regions of Central Mexico host the greatest genetic diversity of cactus pear in the world. This fruit is a many-seeded berry with a thick wall enclosing a delicately flavored flesh. On the basis of seasonal availability and development, there are cactus pears for early, intermediate and late ripening. Thus we hereby analyze the changes in enzymatic activity for several cell wall hydro-lases and their genes, which were isolated by RT-PCR from varieties cultivars with different ripening behavior. The molecular analysis showed differential expression for several genes in an early ripening cultivar 'Naranjona', and in a late ripening cultivar 'Charola'; a constitutive expression of the genes was found. The results suggest a different control between gene expression and enzymatic activity.