2017 ASHS Annual Conference

There have been few reports on hormonal regulation of dormancy in buried seeds with morphological (MD) and morphophysiological dormancy (MPD). The phenology of embryo development and germination in seeds of Aquilegia buergeriana and Adonis amurensis (Ranunculaceae) was investigated in the natural field soil, and the seasonal changes of endogenous phytohormone levels (ABA and GAs) were analyzed. A. buergeriana seeds had MD, and embryo growth and germination were completed within 30 days in the natural field conditions when soil temperatures were high. On the other hand, A. amurensis seeds had MPD, and the seeds experienced warm temperatures in summer followed by cold temperatures in winter to break seed dormancy in the natural environment. In A. buergeriana seeds, ABA content and sensitivity decreased rapidly, and GA content and sensitivity increased rapidly after burial. On the other hand, in A. amurensis seeds, ABA content decreased drastically after burial but GA content did not increase before the seeds experienced temperature changes from high in summer to medium temperatures in autumn in the natural environment. When underdeveloped embryos grew rapidly, ABA was non-detectable and GA content increased. After embryo maturation in autumn, ABA content increased and GA content decreased at the same time, and thus, the seeds remained ungerminated during cold season in winter. When the seeds started to germinate after cold season in winter, GA content increased rapidly. GA₄ played a key role in promoting embryo growth and germination in the seeds with MD and MPD. The changes of GA/ABA ratio were similar to the changes of embryo growth and germination in the buried seeds. These results indicate that MD or MPD in the basal angiosperm taxa is also controlled by a hormone balance model.

(The results of this research were introduced at KSHS 2015 Annual Spring Conference through oral presentation)