Abstract:

The changes in albedo cell wall substances such as water-soluble pectin (WSP), cellulose (CEL), hemicellose (HC)
and lignin and related enzyme activities such as pectinesterase (PME), polygalacturonase (PG) and cellulase (Cx) in Kiyomi
fruits during 120–300 days after flowering were explored and correlated with albedo fracture toughness. The results showed
that the contents of WSP, CEL, HC and lignin decreased during the later stages of maturation; the activities of PG and Cx
increased, whereas the opposite trend was observed for PME activity. Low levels of CEL, HC and lignin and high contents
of WSP were beneficial to reduce the fracture toughness of albedo in Kiyomi fruits. The key hydrolases affecting albedo
fracture toughness in Kiyomi during 210–300 days after flowering were PG and Cx.

Key words: Kiyomi, fracture toughness, cell wall substances, cell wall related enzyme activities