Abstract: In order to understand the role of abscisic acid（ABA）in sweet cherry fruit maturation, one cDNA（PacNCED1）encoding 9-cis-epoxycarotenoid dioxygenase（NCED）as a key enzyme in ABA biosynthesis was cloned from the sweet cherry fruit，and one cDNA（PacACO1）encoding 1-aminocyclopropane-1-carboxylic acid（ACC）oxidase involved in ethylene biosynthesis was cloned from ethephon treated fruits using RT-PCR and RACE-PCR approach. The amino acid sequences of PacNCED1 and PacACO1 showed high homology to those of other NCEDs and ACOs. The expression patterns of PacNCED1 and PacACO1 were determined using RT-PCR and Real time PCR. The results indicated that the PacNCED1 was expressed continuously during the whole period of sweet cherry fruit development and in different tissues. Expression of PacNCED1 gene increased in the flesh and seeds and reached the maximum before maturation and that in pedicle reached the maximum at full maturity of sweet cherry fruit. PacNCED1 gene was weakly expressed in control leaves and roots，but sharply increased in water stressed leaves. Compared to the control，ABA and ethephon treatments could enhance the expression of PacNCED1in fruit，while the NDGA and IAA treatments had no effect. The expression of PacACO1 during sweet cherry fruit development was not detected，but it could be induced with the ethephon and ABA treatments.

Key words: sweet cherry, NCED, ACO, ABA, gene, clone, expression