The different effects of chilling stress under moderate light intensity on photosystem II compared with photosystem I and subsequent recovery in tropical tree species |
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Authors: | Wei Huang Shi-Bao Zhang Kun-Fang Cao |
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Institution: | (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 |
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Abstract: | 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. |
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Keywords: | |
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