PJB-2019-915
Exogenous gibberellin promote epicotyl dormancy breaking of Paeonia emodi through regulating endogenous hormone levels
Zhang Min
Abstract
Paeonia emodi is an important wild germplasm resource for medical utilization and high-quality cutting flowers breeding of herbaceous peony. However, both hypocotyl and epicotyl dormancy are displayed in Paeonia, and incomplete removal of that lead to the failure of germination and seedling formation. The aim of this study was to evaluate the effect of different concentrations of gibberellin (GA3) on the percentage of seedling formation and the endogenous phytohormones content. In this research, embryos of Paeonia emodi were rooted in 1/2 MS culture medium added with 0.6 g•L-1AC in vitro after 30 days, then the rooted embryos were transferred to 1/2 MS culture medium containing different concentrations of GA3 (0, 0.1, 0.3, 0.5, 0.7, 0.9 mg•L-1), and the epicotyl-plumule germination percentage was counted 4 weeks later. Embryos were taken on the 10th, 20th, and 30th day of culture, and four endogenous hormones in the embryos were detected by LC-MS analysis. The results showed that: The adding of 0.3~0.9 mg•L-1 GA3 could completely break the epicotyl dormancy of Paeonia emodi. The best results were obtained with the use of 0.5 mg•L-1 GA3, and the epicotyl-plumule germination percentage was up to 90.00 %±10.00%. In 0.5 mg•L-1 GA3 treatment, the ABA content continued to decrease while the content of GA3 increased in the first 20 days, and then decreased. On the 30th day after treatment, the GA3/ABA ratio of 0.5 mg•L-1 GA3 treated which successfully breaking dormancy was much higher than control treatment. It suggests that exogenous adding of GA3 restrains the synthesis of ABA in the embryo of Paeonia emodi, which regulates the equilibrium relationship between the epicotyl dormant promoter and inhibitor, and finally achieves the break of dormancy.
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