尖叶拟船叶藓的77 K荧光光谱及对强光照的短期适应

Fluorescence Emission Spectra at 77 K and Capacity of Short-term Regulation to Light of Dolichomitriopsis diversiformis

报道了东亚特有濒危植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)在不同光质的光照诱导下的低温77 K荧光光谱及状态转移的初步研究结果。实验中,尖叶拟船叶藓在77 K下出现了3条发射带,分别是F680、F685、F720nm,并没有出现存在于大部分高等植物中的F695nm和F740nm两个峰。经过PSII光诱导后,在77K下出现了F680nm,这个峰在77K下出现是首次报道,而以前的研究认为只在4K下才出现这一条光谱带。这一结果表明尖叶拟船叶藓叶绿体的两个光系统结构与其他高等植物存在着差异。在自然光下,PSII与PSI的总能量比是2.04,经过15 min的PSII光(670nm)诱导后,PSII与PSI的总能量比变成了1.28(状态2),当用15 min的PSI光(716 nm)照射后,PSII与PSI的总能量比从2.04变成了3.41(状态1)。在自然光下,由尖叶拟船叶藓的光系统的外部LHCII所吸收的激发能是整个光系统激发能的21.19％。这说明尖叶拟船叶藓对光的短期调节能力是21.19％。尖叶拟船叶藓的光系统的外部LHCII有51.7％位于PSII中,48.3％在PSI中。

The 77 K fluorescence of Dolichomitriopsis diversiformis shows 3 emission bands: F680, F685, F720 respectively, although not all peaks would appear in an experiment. The emission peaks at 695 nm and 740 nm which exist in the flourescence spectra of most highter plants were not detected. After induction of PSⅡ light, F680 appears at 77 K, while previous studies have shown that F680 only appears at 4 K. These results mean that the structure of the two photosystems in chloroplast of D. diversiformis is differrent from that of other higher plants. Under natural light the total energy ratio of PSⅡ to PSⅠ is 2. 04. After induction of 15 min of PSⅡ light (670 nm), the total energy ratio of PSⅡ to PSⅠ becomes 1. 28 (state 2). While illumination PSI light(716 nm) for 15 min light results in the change of total energy ratio of PSII to PSI from 2. 04 to 3. 41 (state 1) . Under natural the excitation energy absorbed by outer LHCⅡ of D. diversiformis accounts for 21. 19% of the total excitation energy of photosystems. This means that the capacity of short-term regulation of D. diversiformis to light is 21. 19% . 51. 1% of outer LHCII of D. diversiformis locates in PSII and 48. 3% in PSⅠ.