典型熱帶植物對零度以上低溫十分敏感,，但機(jī)理尚不清楚,。
近日,，中國科學(xué)院西雙版納熱帶植物園曹坤芳研究組通過模擬零上低溫和中等強(qiáng)度光照對4種熱帶樹木光合系統(tǒng)的影響，發(fā)現(xiàn)熱帶植物的光系統(tǒng)II比光系統(tǒng)I對零上低溫更敏感,，其中一個種光系統(tǒng)I也遭遇嚴(yán)重?fù)p傷,，低溫處理后其光合系統(tǒng)的功能不能恢復(fù),，隨后葉片死亡脫落。
研究表明,，典型的熱帶植物不能在冬季較冷涼的北熱帶,、亞熱帶地區(qū)正常生長的一個重要的原因是短時間的低溫光照脅迫就可能導(dǎo)致其葉片受損嚴(yán)重并死亡。該項(xiàng)研究結(jié)果與傳統(tǒng)認(rèn)識相悖,，傳統(tǒng)研究認(rèn)為冷敏感植物光系統(tǒng)I比光系統(tǒng)II更敏感,。
相關(guān)研究成果發(fā)表在《光合作用研究》（Photosynthesis Research）期刊上，評審專家認(rèn)為該論文的發(fā)現(xiàn)對于認(rèn)識熱帶植物低溫敏感性具有重要的意義,。(生物谷www.bioon.net)
生物谷推薦原文出處：
Photosynthesis Research DOI：10.1007/s11120-010-9539-7
The different effects of chilling stress under moderate light intensity on photosystem II compared with photosystem I and subsequent recovery in tropical tree species
Wei Huang1, 2 , Shi-Bao Zhang1 and Kun-Fang Cao1, 2
(1) Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 666303 Mengla, Yunnan, China
(2) School of Life Science, University of Science and Technology of China, 230027 Hefei, Anhui, China
Tropical plants are sensitive to chilling temperatures above zero but it is still unclear whether photosystem I (PSI) or photosystem II (PSII) of tropical plants is mainly affected by chilling temperatures. In this study, the effect of 4°C associated with various light densities on PSII and PSI was studied in the potted seedlings of four tropical evergreen tree species grown in an open field, Khaya ivorensis, Pometia tomentosa, Dalbergia odorifera, and Erythrophleum guineense. After 8 h chilling exposure at the different photosynthetic flux densities of 20, 50, 100, 150 μmol m?2 s?1, the maximum quantum yield of PSII (F v /F m) in all of the four species decreased little, while the quantity of efficient PSI complex (P m) remained stable in all species except E. guineense. However, after chilling exposure under 250 μmol m?2 s?1 for 24 h, F v /F m was severely photoinhibited in all species whereas P m was relative stable in all plants except E. guineense. At the chilling temperature of 4°C, electron transport from PSII to PSI was blocked because of excessive reduction of primary electron acceptor of PSII. F v /F m in these species except E. guineense recovered to ~90% after 8 h recovery in low light, suggesting the dependence of the recovery of PSII on moderate PSI and/or PSII activity. These results suggest that PSII is more sensitive to chilling temperature under the moderate light than PSI in tropical trees, and the photoinhibition of PSII and closure of PSII reaction centers can serve to protect PSI.
