Induction of adventitious buds and study on endogenous hormones in Chamaecyparis hodginsii

Focusing on the optimization of the adventitious bud induction system of Chamaecyparis hodginsii, a native species of Fujian, this study aims to provide theoretical support for the conservation of its germplasm resources and the development of in vitro propagation techniques.

By screening 6-BA, ZT, KT and other cytokinins, determining the most suitable implants, the best sterilization formula for implants, and the best incubation formula for adventitious bud induction, and exploring the mechanism of endogenous hormones in germination.

1) C. hodginsii is most suitable for extraction as a young, young, sprouted stem that was born in the year; 2) 75% alcohol disinfection for 10 s, 4% sodium hypochlorite disinfection for 600 s was the best disinfection formula of explants, which significantly reduced the risk of contamination; 3) The optimum culture medium for adventitious bud induction was MS + Sucrose 30.0 g/L + Agar 6.5 g/L + 0.1 mg/L KT, the rate of bud induction was 85.56%. At the same time, for the common browning problem in tissue culture of C. hodginsii, we found that the combination of AC and VC treatment had significant anti-browning effect, and the pollution rate was below 10%, effectively improving the culture efficiency; 4) The dynamic changes in the endogenous hormone levels during the process of adventitious bud induction indicate that the concentrations and ratios of IAA, ABA, GA₃, and CTK exhibit regular fluctuations. Among these, ABA and GA₃ have antagonistic effects. The balance between the ratios of IAA/ABA and CTK/IAA is the core mechanism regulating the bud germination of C. hodginsii. The period of 7-14 days is when the concentrations of IAA and the ratios of IAA/ABA, CTK/IAA reach their peak levels, making it a critical stage for the bud germination of C. hodginsii. During this period, the synergistic action of these hormones collectively contributes to their ability to adapt to the environment and promote growth and development.

This study has preliminarily established a low-pollution adventitious bud induction system for C. hodginsii, clarified the impact of different cultivation conditions on the content of endogenous hormones, and revealed the regulatory rules of endogenous hormones in the process of adventitious bud induction.