Cyclic Electron Flow Plays an Important Role in Photoprotection of Tropical Trees Illuminated at Temporal Chilling Temperature
Cyclic Electron Flow Plays an Important Role in Photoprotection of Tropical Trees Illuminated at Temporal Chilling Temperature
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循环电子流在临时寒冷温度下照明的热带树木的光保护中发挥重要作用
DOI：
10.1093/pcp/pcq166
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发表时间：
2011-02-01
影响因子：
4.9
通讯作者：
Cao, Kun-Fang
中科院分区：
文献类型：
--
作者：
Huang, Wei;Zhang, Shi-Bao;Cao, Kun-Fang
我们的前期研究表明，热带树木的PSII比PSI对寒冷和光胁迫更敏感，几内亚红属植物对寒冷胁迫的敏感性高于降香黄檀（Dalbergia odorifera）和Khaya ivorensis，但其潜在的生理机制尚不清楚。虽然最近的研究报道了循环电子流（cyclic electron flow， CEF）在光保护中起重要作用，但CEF在保护热带树种PSI和PSII中的作用尚不清楚。本文研究了不同时间降温温度对上述热带常绿树种PSII能量分布、P700氧化还原状态和CEF的影响。结果表明，PSII反应中心在冷却温度下过闭导致PSII中激发态压力过高。在弱光下瞬时冷却温度下，所有树种的PSI受体侧限制[Y(NA)]均低于25℃时。虽然在弱光条件下，豚鼠和猕猴的CEF [Y(CEF)]的有效量子产率没有受到显著刺激，但Y（CEF）与PSII [Y(II)]的有效量子产率之比显著增加。在低温条件下，Y(CEF)/Y（II）在伊氏家鼠和臭臭家鼠体内的表达量明显高于对低温敏感的几内亚家鼠。这些结果表明，刺激Y(CEF)/Y（II）在保护PSI和PSII免受低温胁迫引起的光抑制中起重要作用。
Our previous study indicated that PSII is more sensitive to chilling and light stress than PSI in tropical trees, and Erythrophleum guineense is more sensitive to chilling stress than Dalbergia odorifera and Khaya ivorensis, but the underlying physiological mechanisms are unclear. Although recent studies have reported that cyclic electron flow (CEF) plays an important role in photoprotection, the role of CEF in protecting PSI and PSII of tropical tree species remains unclear. We investigated the effect of temporal chilling temperature on energy distribution in PSII, the redox state of P700 and CEF in the above-mentioned tropical evergreen tree species grown in an open field. Our results indicated that the overclosure of PSII reaction centers at chilling temperature led to excess excitation pressure in PSII. At the temporal chilling temperature under low light, PSI acceptor side limitation [Y(NA)] was lower than those at 25C for all species. Although the effective quantum yield of CEF [Y(CEF)] was not significantly stimulated in E. guineense and K. ivorensis under temporal chilling at low light levels, the ratio of Y(CEF) to the effective quantum yield of PSII [Y(II)] significantly increased. Under chilling conditions Y(CEF)/Y(II) was stimulated much more in K. ivorensis and D. odorifera compared with that in the chilling-sensitive E. guineense. These results suggested that stimulation of Y(CEF)/Y(II) plays an important role in protecting PSI and PSII from photoinhibition caused by chilling stress.