Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
J Plant Physiol. 2010 Nov 1;167(16):1390-7. doi: 10.1016/j.jplph.2010.05.028. Epub 2010 Aug 16.
The moss Syntrichia caninervis (S. caninervis) is one of the dominant species in biological soil crusts of deserts. It has long been the focus of scientific research because of its ecological value. Moreover, S. caninervis has a special significance in biogenesis research because it is characterized by its fast restoration of photosynthesis upon onset of rehydration of the desiccated organism. In order to study the mechanisms of rapid photosynthetic recovery in mosses upon rewatering, we investigated the kinetics of the recovery process of photosynthetic activity in photosystem (PS) II, with an indirect assessment of the photochemical processes based on chlorophyll (Chl) fluorescence measurements. Our results showed that recovery can be divided into two phases. The fast initial phase, completed within 3 min, was characterized by a quick increase in maximal quantum efficiency of PSII (F(v)/F(m)). Over 50% of the PSII activities, including excitation energy transfer, oxygen evolution, charge separation, and electron transport, recovered within 0.5 min after rehydration. The second, slow phase was dominated by the increase of plastoquinone (PQ) reduction and the equilibrium of the energy transport from the inner antenna to the reaction center (RC) of PSII. Analysis of the recovery process in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) revealed that blocking the electron transport from Q(A) to Q(B) did not hamper Chl synthesis or Chl organization in thylakoid membranes under light conditions. A de novo chloroplast protein synthesis was not necessary for the initial recovery of photochemical activity in PSII. In conclusion, the moss's ability for rapid recovery upon rehydration is related to Chl synthesis, quick structural reorganization of PSII, and fast restoration of PSII activity without de novo chloroplast protein synthesis.
金发藓（Syntrichia caninervis）是荒漠生物土壤结皮中的优势物种之一。由于其生态价值，它长期以来一直是科学研究的焦点。此外，由于其干燥生物体再水合时光合作用迅速恢复的特点，S. caninervis 在生物发生研究中具有特殊意义。为了研究苔藓类植物再水合时光合作用快速恢复的机制，我们研究了光合作用系统（PS）II 中光合作用活性恢复过程的动力学，通过叶绿素（Chl）荧光测量对光化学过程进行间接评估。我们的结果表明，恢复可以分为两个阶段。快速初始阶段在 3 分钟内完成，其特征是 PSII 最大量子效率（F(v)/F(m)）快速增加。超过 50%的 PSII 活性，包括激发能转移、氧气释放、电荷分离和电子传递，在再水合后 0.5 分钟内恢复。第二阶段是缓慢阶段，主要由质体醌（PQ）还原的增加和从天线到 PSII 反应中心（RC）的能量传递的平衡决定。在 3-（3,4-二氯苯基）-1,1-二甲基脲（DCMU）存在下分析恢复过程表明，电子从 Q(A)到 Q(B)的传递受阻不会在光照条件下阻碍类囊体膜中 Chl 的合成或 Chl 组织。对于 PSII 光化学活性的初始恢复，新的叶绿体蛋白合成不是必需的。总之，苔藓类植物再水合时的快速恢复能力与 Chl 合成、PSII 的快速结构重组以及新的叶绿体蛋白合成无关的 PSII 活性的快速恢复有关。
