Abstract:

In order to analyze the signal effect of H₂O₂ on seasonal dormancy release of Japanese apricot induced by exogenous GA₄，the buds of Japanese apricot and transgenic poplar with PmRGL2 gene were taken as the plant materials to investigate the content of H₂O₂，activities of antioxidant enzymes and gene transcriptional expression related to antioxidant enzymes and signal transduction. The results showed that the sprout rate of flower buds of Japanese apricot treated by GA₄ was significant higher than that of the control and the content of H₂O₂ accompanied with the expression of signal transduction related genes and reached to a peak at the time of dormancy release. The chilling requirement of‘Taoxingmei’and ‘Bungo’Japanese apricots are 574 CH（Chilling hours）and 1 108 CH，respectively. The content of H₂O₂ in leaf buds did not have significant difference in both cultivars before and after dormancy release，while the activities of antioxidant enzymes were higher in the former one. The down-regulation expression of NADPHoxi and up-regulation of expression of the antioxidant enzymes related genes contributed to maintain the content of H₂O₂ in transgenic poplar with a low level，which could affect the genes expression associated with gibberellin synthesis and signal transduction. Above all，we suggested that GA₄ may regulate the genes expression encoding antioxidant enzymes to affect the content of H₂O₂ which acted as a signal molecular to lead to signal gene expression changes related to seasonal dormancy release in Japanese apricot.

Key words: Japanese apricot, dormancy, GA₄, floral bud, vegetative bud, H₂O₂