Compositional changes in cell wall polysaccharides from Japanese plum ( Prunus salicina Lindl.) during growth and on-tree ripening.

Climacteric Japanese plums were harvested at six developmental stages with no intermediate storage period, and cell wall compositional changes were analyzed. Arabinose proved to be the principal neutral monosaccharide constituent in cell walls during growth and the most dynamic neutral sugar in pectic fractions. Arabinose loss from tightly bound pectins was found to be a relatively early feature in the sequence of cell wall biochemical modifications, thus suggesting a softening-related role during Japanese plum on-tree ripening. Depolymerization of matrix glycans started at the end of the cell expansion phase and increased throughout ripening. Pectin solubilization was first detected during early ripening. Firmness loss did not correlate with polyuronide depolymerization early in ripening, but the last softening phase was associated with a strong depolymerization of cell wall polyuronides as well as a decrease in the arabinose/galactose ratio in loosely bound pectins. This is the first work that characterizes the temporal sequence of cell wall polysaccharide changes in Japanese plum.