Higher electron transport rate observed at low intercellular CO2 concentration in long-term drought-acclimated leaves of Japanese mountain birch (Betula ermanii)
Higher electron transport rate observed at low intercellular CO2 concentration in long-term drought-acclimated leaves of Japanese mountain birch (Betula ermanii)
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DOI：
10.1034/j.1399-3054.2003.00120.x
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发表时间：
2003-07-01
影响因子：
6.4
通讯作者：
Maruyama, Y
中科院分区：
文献类型：
--
作者：
Kitao, M;Lei, TT;Maruyama, Y
研究了长期干旱胁迫对岳桦（Betula ermanii Cham.）的叶绿素荧光和气体交换测量。通过将灌溉频率从每天（对照）减少到每周两次和每周一次来在盆栽植物中施加干旱胁迫。将在完全胁迫条件下发育的30天龄的叶用于测量。在干旱胁迫植物中原位观察到的净CO2同化率（A）的下降是由于气孔关闭导致的较低的胞间CO2浓度（C-i），但羧化效率不受影响，因为浇水后A/C-i响应的初始斜率没有差异。尽管在C-i低于270 mumol mol（-1）时，A无处理差异，（与环境空气在360 mumolmol（-1）CO2），更高的电子传递速率（ETR），光化学猝灭（q（P））和开放PSII的能量转换效率在干旱胁迫下，在给定的C-i下，观察到类似或甚至更低的非光化学猝灭（NPQ）。（每周两次和一次灌溉），这表明更高的分数开放PSII通过更高的电子流，而不是通过PSII天线的热耗散实现的能量耗散。每周浇水一次的植物表现出较低的总碳同化率ETR（A*/ETR）的比例，这表明一个增强的电子流的替代途径可能涉及的Mehler-过氧化物酶（MP）反应所示的较高的Phi（PSII）在给定的Phi（CO2）在非光呼吸条件下。另一方面，每周两次浇水的植物表现出几乎相同的A*/ETR和Phi（PSII）-Phi（CO2）的关系，表明在轻度干旱胁迫下没有增强的替代途径。
The influence of long-term drought stress on photosynthesis of Japanese mountain birch (Betula ermanii Cham.) was examined using chlorophyll fluorescence and gas exchange measurements. Drought stress was imposed in potted plants by reducing irrigation frequency from daily (control) to twice-weekly and once-weekly. Thirty-day-old leaves, which had developed under fully stressed conditions, were used for the measurements. The decline in net CO2 assimilation rate (A) observed in situ in drought-stressed plants resulted from a lower intercellular CO2 concentration (C-i) due to stomatal closure but the carboxylation efficiency was not affected as there was no difference in the initial slope of the A/C-i response after watering. Although there were no treatment differences in A at C-i below 270 mumol mol(-1) (with ambient air at 360 mumol mol(-1) CO2), higher electron transport rate (ETR), photochemical quenching (q(P) ) and the efficiency of energy conversion of open PSII (F-v'/F-m'), and similar or even lower non-photochemical quenching (NPQ) were observed at a given C-i in drought-stressed plants (of both twice- and once-weekly irrigation), suggesting a higher fraction of open PSII resulting from energy dissipation achieved through higher electron flow rather than through thermal dissipation in PSII antennae. The once-weekly watered plants showed a lower ratio of gross carbon assimilation rate to ETR (A*/ETR), suggesting an enhanced alternative pathway of electron flow probably involving the Mehler-peroxidase (MP) reaction as indicated by a higher Phi(PSII) at a given Phi(CO2) under non-photorespiratory conditions. On the other hand, plants of twice-weekly watering exhibited almost the same A*/ETR and Phi(PSII)-Phi(CO2) relationship as control plants, indicating no enhanced alternative pathways under mild drought stress.