Chilling-injury in cucumbers. V. Polysaccharide changes in cell walls

A decline in the hot-water-soluble pectin and an increase in the hot-water-insoluble pectin were observed when cucumber fruits were subjected to chilling temperatures. Infrared absorption spectra revealed the presence of highly esterified carboxyl groups in the soluble pectin, and of free carboxyl groups in the insoluble pectin. An increase of the insoluble pectin during chilling was also found in other chilling-sensitive plants. From these results it is suggested that a de-esterification of pectin and the concomitant increase of polymeric pectin takes place during chilling, making cell walls firmer, and that these pectic changes may be a characteristic common to a number of chilling-sensitive plants.