5. Conclusions
Premature fruit drop is often associated with abiotic stresses. During the early development, apple fruit are exposed to abnormal cold conditions following temperature fluctuations. Our results indicate that apple trees having early developing fruit produce signals for abscission induction in response to cold. Once the initial elevation of ABA biosynthesis in the pedicel spreads to adjacent organs, increased ABA signalling orchestrates cold response. AZ development is coordinated with the signals for cell wall modification produced in the branch and inhibition of negative hormones in the fruit. Based on these findings, we suggest that ABA-dependent responses to cold contribute to abscission induction signalling in early developing apple.