Advances in research on the relationship between pectolytic enzymes and fruit softening

Pectolytic enzymes are widespread in plants and mainly include pectinmethylesterase(PME),pectate lyase(PEL),endo-polygalacturonase(endo-PG),exo-polygalacturonase(exo-PG),β-galactosidase,α-L-arabinofuranosidase and rhamnogalacturonase in fruit tissues.They constitute a unique group of enzymes that are responsible for the degradation of pectin and pectic substances in fruit cell walls,and make cell-to-cell separation and disassembly of the cell wall structure and lead to fruit-tissue softening.This review summarizes our current knowledge about pectolytic enzymes and their corresponding genes that participate in the degradation of pectin polysaccharides in fruit plants.In addition,the existing problems and direction of fruit softening study in near future are put forward.