Abstract
Japanese beech (Fagus crenata) is deciduous broad-leaved tree species and differently responses to high-light between the Pacific Ocean type (PAO) and the Japan Sea type (JAS). When PAO and JAS saplings were grown under high-light (H) and low-light (L) condition, only JAS-H turned its leaf color to pale green. To elucidate these phenomena, we analyzed about the two photosystems. JAS-H decreased D1-protein level, resulting in decreasing in Fv/Fm and ETR, while PAO-H highly maintained. P-700 photooxidation kinetics showed that the intersystem electron pool size in JAS-H was 1.4-times higher than that in PAO-H. Furthermore, re-reduction kinetics of P-700+ showed that the PS I cyclic electron transport in PAO-H was 1.2-times faster than that in JAS-H. These results demonstrated that PAO shows acclimatization mechanisms against high-light, whereas JAS is vulnerable to continuous high-light due to increases of the intersystem electron pool size and suppression of electron transport activity.
