Abstract
Spraying 500mg·liter-1 abscisic acid (ABA) on fruit 90 days after full bloom (DAFB) enhanced sugar accumulation in 'Hakuho' peach fruit which was accompanied by a temporal rise in ABA content. Simultaneously, the activity of sorbitol oxidase (SOX), a predominant enzyme in the metabolism of the translocated sugar alcohol, sorbitol, increased. Activities of the sugar metabolizing enzymes, sucrose synthase (SS), sucrose phosphate synthase (SPS), and acid invertase were unaffected by the ABA treatment, whereas NAD+-dependent sorbitol dehydrogenase (SDH) activity was not detected. These results indicate that ABA may stimulate SOX activity, enhancing sugar accumulation in the fruit. Possible mechanisms of accelerated sugar accumulation by ABA are discussed in relation to sugar metabolism.
