Pectin methyl esterase (PME), catalysing
hydrolysation of methyl ester group of pectin, is a key control
enzyme for both assembly and disassembly of pectic network
(Willats, McCartney, Mackie, & Knox, 2001) by determining tissue
integrity during fruit senescence, perhaps by regulating cation
binding to cell wall (Tieman & Handa, 1994).