Departamento de Biología Vegetal, Facultad de Biología, Universidad de Murcia, Murcia, Spain.
J Plant Physiol. 2010 Jun 15;167(9):732-8. doi: 10.1016/j.jplph.2009.12.013. Epub 2010 Feb 20.
Sun (Chrysanthemum morifolium) and shade (Spathiphyllum wallisii) plants were used to study the effects of drought, heat and high illumination. The stress conditions caused a greater accumulation of hydrogen peroxide in Chrysanthemum morifolium than in Spathiphyllum wallisii leaves. They also resulted in down-regulation of linear electron transport in the leaves of both species, as indicated by a gradual reduction in the photochemistry efficiency of PS II, which was associated with an increase in the non-photochemical quenching of fluorescence. Only a slight decrease in F(v)/F(m) was observed under stress conditions in either plant species, suggesting that the chloroplast is protected by mechanisms that dissipate excess excitation energy to prevent damage to the photosynthetic apparatus. In addition to the effects on photosynthetic activity, changes were also observed by immunoblot analysis in the plastidial NADH DH complex, PTOX and PGR5. The quantities of the PTOX and NDH-H subunit of the thylakoidal NADH DH complex, and the NADH DH activity in the thylakoid membranes were similar in control plants of both species and increased in stressed plants, particularly in Spathiphyllum wallisii. The level of PGR5 polypeptide was higher in Chrysanthemum morifolium than in Spathiphyllum wallisii control plants, while after stress, the quantity of PGR5 increased significantly in Chrysanthemum morifolium and remained constant in Spathiphyllum wallisii. These results indicate that the relative importance of chlororespiration and the cyclic electron pathways in the tolerance to drought, heat and high illumination differs in sun and shade plants, indicating different adaptive mechanisms to the environment. In the conditions studied, the PGR5-dependent cyclic pathway is more active in Chrysanthemum morifolium, a sun species, whereas in Spathiphyllum wallisii, a shade species, other ways involving the NADH DH complex and PTOX are stimulated in response to stress, which results in lower levels of ROS accumulation in the leaves.
利用菊花（Chrysanthemum morifolium）和文殊兰（Spathiphyllum wallisii）研究干旱、高温和高光条件下的胁迫反应。胁迫导致菊花叶片中过氧化氢的积累量大于文殊兰叶片。同时，胁迫还导致两种植物叶片线性电子传递的下调，表现为 PSII 光化学效率的逐渐降低，这与荧光非光化学猝灭的增加有关。在两种植物中，胁迫条件下仅观察到 F(v)/F(m) 略有下降，表明叶绿体受到保护，通过耗散过剩激发能的机制来防止光合作用装置的损伤。除了对光合作用活性的影响外，免疫印迹分析还观察到质体 NADH 脱氢酶复合物、PGR5 和 PTOX 的变化。两种植物的对照植株中，类囊体 NADH 脱氢酶复合物的 PTOX 和 NDH-H 亚基以及类囊体膜中的 NADH 脱氢酶活性的数量相似，在胁迫植株中增加，特别是在文殊兰中。PGR5 多肽的水平在菊花对照植株中高于文殊兰，而胁迫后，菊花中 PGR5 的数量显著增加，文殊兰中则保持不变。这些结果表明，在耐干旱、高温和高光条件下，阴生和阳生植物中叶绿体呼吸和循环电子途径的相对重要性不同，表明它们对环境具有不同的适应机制。在研究的条件下，PGR5 依赖性的循环途径在阳性植物菊花中更为活跃，而在阴性植物文殊兰中，涉及 NADH 脱氢酶复合物和 PTOX 的其他途径在胁迫下被激活，从而导致叶片中 ROS 积累水平较低。
