生长温度对烟草叶片环式电子传递活性的影响（英文）

Effect of Growth Temperature on the Activity of Cyclic Electron Flow in Tobacco Leaves

高等植物的光合机构在环境胁迫条件下非常容易产生光抑制,环式电子传递在光合机构的光保护中发挥着重要的作用。但是,生长温度对环式电子传递的影响并不清楚。本研究测定了在24/18℃和32/26℃条件下生长40天的烟草(K326)叶片的气体交换、叶绿素荧光和P700氧化还原态的光响应曲线。结果表明,烟草叶片在两种生长温度下的的光合能力、光化学淬灭、非光化学淬灭和通过光系统II的电子传递速率(ETR II)均没有差异。但是,在强光条件下,生长在24/18℃的叶片比生长在32/26℃的具有更高的通过光系统I的电子传递速率(ETR I)和ETR I/ETR II比值。短时间的强光处理后,生长在24/18℃的叶片具有较高的光系统II最大量子产额(Fv/Fm),表明环式电子传递活性的上调有助于缓解生长在24/18℃的叶片光系统II受到的光损伤。综上所述,环式电子传递活性的增强是植物适应较低生长温度的重要策略。

Cyclic electron flow （CEF） around photosystem I （PSI） is an important mechanism for photoprotection in higher plants under environmental stresses. However, the response of CEF activity to growth temperature has not been clarified. We here monitored gas exchange, chlorophyll fluorescence, and the P700 redox state over a range of light intensities in leaves of tobacco cultivar ＇ k326＇ grown at 24/18 ℃ and 32/26 ℃ （day/night）. No significant difference was found in the capacity of photosynthetic CO2 assimilation between the plants grown at 24 ℃ and 32 ℃. In addition, the light response changes in the photochemical quenching of photosystem II （ Y （II） ） and non-photochemical quenching （NPQ） did not differ significantly between those plants. Light response curves indicated that the plants grown at 24 ℃ and 32 ℃ displayed the same level of electron flow through PSII （ETR II） irrespective of light intensity. However, under intense light, plants grown at 24 ℃ showed significantly higher electron flow through PSI （ETR I）. The ETR I/ETR II ratio was significantly higher in plants grown at 24 ℃ when exposed to intense light. Furthermore, after short-term treatment with strong light at 24 ℃, the maximum quantum yield of photosystem II （ Fv/Fm ） was significantly higher in plants grown at 24 ℃ than that grown at 32 ℃. Taken together, our results suggest that enhancement of CEF activity in plants grown at 24 ℃ alleviates PSII photoinhibition, which is an important strategy in tobacco for acclimating to a relatively low growth temperature.