Xyloglucan-derived oligosaccharides induce ethylene synthesis in persimmon (Diospyros khaki L.) fruit

In this work the effect of injection of xyloglucan-derived oligosaccharides (XGOs) into whole persimmon (Diospyros khaki L.) fruits on ethylene biosynthesis was investigated. Fruits collected during different ripening stages produced low levels of ethylene without a climacteric-like peak. Pretreatment of these fruits with 10 cm³ C2H4 m^-3 for 8 h stimulated little or no endogenous ethylene production. However, when persimmon fruits were injected with a mixture of XGOs a burst in ethylene production was observed compared with water-injected control fruits or fruits injected with different monosaccharide solutions. In order to study the influence of oligosaccharide structure and fruit ripening stage on the ability of XGOs to induce ethylene synthesis, fucosylated and non-fucosylated XGOs were injected into persimmon fruits harvested at two different ripening stages. Both oligosaccharide structures were able to induce ethylene production. Induction of ethylene by XGOs was much more evident in fruits harvested later in time, indicating that the process is developmentally regulated. The levels of 1-aminocyclopropane-1-carboxylic acid (ACC) in injected persimmon fruits were also examined. This study showed that the increase in the rate of ethylene biosynthesis induced by XGOs was accompanied by the accumulation of its metabolic precursor ACC.