XYLOGLUCAN-DERIVED OLIGOSACCHARIDES INDUCE ETHYLENE SYNTHESIS IN PERSIMMON (DIOSPYROS-KAKI L.) FRUIT

In this work the effect of injection of xyloglucan-derived oligosaccha rides (XGOs) into whole persimmon (Diospyros kaki L.) fruits on ethyle ne biosynthesis was investigated, Fruits collected during different ri pening stages produced low levels of ethylene without a climacteric li ke peak. Pretreatment of these fruits with 10 cm(3) 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 ethy lene production was observed compared with water-injected control frui ts or fruits injected with different monosaccharide solutions. In orde r to study the influence of oligosaccharide structure and fruit ripeni ng stage on the ability of XGOs to induce ethylene synthesis, fucosyla ted and non-fucosylated XGOs were injected into persimmon fruits harve sted at two different ripening stages. Both oligosaccharide structures were able to induce ethylene production, Induction of ethylene by XGO s was much more evident in fruits harvested later in time, indicating that the process is developmentally regulated, The levels of 1-aminocy clopropane-1-carboxylic acid (ACC) in injected persimmon fruits were a lso examined, This study showed that the increase in the rate of ethyl ene biosynthesis induced by XGOs was accompanied by the accumulation o f its metabolic precursor ACC.