Departamento Biología Vegetal, Facultades de Ciencias y Farmacia, Universidad de Navarra, Pamplona, Spain.
J Plant Physiol. 2010 Jun 15;167(9):701-8. doi: 10.1016/j.jplph.2009.12.012. Epub 2010 Feb 20.
Greenhouse experiments were conducted to compare stress effects caused by Verticillium dahliae and drought on gas exchange, chlorophyll (Chl) fluorescence and photosynthetic pigments of pepper plants. Three treatments were compared: Verticillium inoculated plants (+V), non-inoculated well-watered plants (-V) and non-inoculated plants subjected to progressive drought (D). Gas exchange, fluorescence and photosynthetic pigments were measured and represented along a gradient of relative water content (RWC) and stomatal conductance (g(s)). Net photosynthesis (A) and electron transport rate (ETR) decreased, as RWC and g(s) declined, similarly in both +V and D plants. However, dark respiration (R(D)) and photorespiration (R(L)) tended to increase in inoculated plants compared to those subjected to soil drought, as g(s) decreased. Photoinhibitory damage was not observed in infected or in droughted plants. Soil drought decreased intrinsic PSII efficiency (Phi(exc.)), which seemed to result in part from enhanced xanthophyll cycle- and/or lutein-related thermal energy dissipation. Nevertheless, the fact that 1-Phi(exc.) increased in D only at high values of the de-epoxidation state of the xanthophyll cycle (DPS) suggests that DeltapH could be the major factor controlling thermal energy dissipation in this treatment. By contrast, antheraxanthin, zeaxanthin and lutein, as well as Phi(exc.), were not markedly affected in +V. Water stress appeared to be the main limitation to photosynthesis in Verticillium infected plants, probably through stomatal closure, together with impaired mesophyll conductance (g(m)). However, our results indicate differential effects of V. dahliae on dark respiration, photorespiration, g(m) and on the capability of thermal energy dissipation under low g(s) values.
温室实验比较了由黄萎病菌和干旱引起的胁迫对辣椒植株气体交换、叶绿素（Chl）荧光和光合色素的影响。比较了三种处理方式：接种黄萎病菌的植株（+V）、未接种且水分充足的植株（-V）和未接种且逐渐干旱的植株（D）。测量并沿相对水含量（RWC）和气孔导度（g(s)）梯度表示气体交换、荧光和光合色素。净光合速率（A）和电子传递速率（ETR）随着 RWC 和 g(s)的下降而下降，+V 和 D 植株的下降趋势相似。然而，与遭受土壤干旱的植株相比，接种植株的暗呼吸（R(D)）和光呼吸（R(L)）随着 g(s)的下降而趋于增加。在感染或干旱的植株中未观察到光抑制损伤。土壤干旱降低了 PSII 内在效率（Phi(exc.)），这似乎部分归因于增强的叶黄素循环和/或叶黄素相关的热能耗散。然而，在 D 中仅在叶黄素循环去氧化态（DPS）高值时 1-Phi(exc.)增加的事实表明，DeltapH 可能是控制该处理中热能耗散的主要因素。相比之下，在+V 中，花药黄质、玉米黄质和叶黄素以及 Phi(exc.)并没有明显受到影响。水胁迫似乎是感染黄萎病菌的植物光合作用的主要限制因素，可能是通过气孔关闭以及受损的叶肉导度（g(m)）。然而，我们的结果表明，黄萎病菌对暗呼吸、光呼吸、g(m)和在低 g(s)值下热能耗散能力的影响存在差异。
