Changes in cell wall polysaccharides in kiwifruit (Actinidia chinensis Planch cv. Yellow Koshin) during softening on the vine.

摘要

The mechanism of softening and cell wall polysaccharide changes in kiwifruits (A. chinensis cv. Yellow Koshin) on the vine were compared with changes induced by ethylene treatment. Cell wall polysaccharides were prepared from 80% alcohol-insoluble residues by extracting the residues with water, EDTA, HCl and KOH in succession. The decrease in the amount of monosaccharides in the water-insoluble fraction (WIF) derived from EDTA, HCl and KOH soluble fractions was investigated. Ethylene evolution wasnot detected in the fruit during softening on the vine. Fruit softening on the vine was accompanied by a decrease in galacturonic acid, but not of neutral sugars in the WIF. Ethylene treatment caused a sharp decrease in rhamnose, arabinose and galactoselevels in the WIF, and galacturonic acid decreased with or without ethylene treatment. It is suggested that fruit softening on the vine is associated with the dissolution of homogalacturonan which is insensitive to ethylene, and that ethylene treatment induced solubilization of homogalacturonan and rhamnogalacturonan, followed by fruit softening.