Postharvest fruit softening in apple
is regulated by the activities of cell wall hydrolysis enzymes, and
ethylene dependent polygalacturonase (Costa et al., 2010), which
consequently modifies the cell wall polysaccharide architecture.
Polygalacturonase is involved in the hydrolytic cleavage of -(1-4)
galacturonan linkage and is responsible for pectin disassembly during
fruit softening (Fischer and Bennett, 1991). Loss of fruit firmness
in the present studies due to delayed harvest may be attributed
to the same process of depolymerisation of pectin in the middle
lamella of fruit cell walls or increased content of water-soluble
pectin that caused loss of cell-to-cell wall adhesion. Loss of firmness
in‘Cripps Pink’ apple withdelayedharvesting inthepresent study is
consistent with results reported earlier for ‘Royal Gala’ (Johnston et