Plant Physiology Division, National Botanical Research Institute (NBRI-CSIR), Rana Pratap Marg, Lucknow, Uttar Pradesh 226001, India.
J Plant Physiol. 2010 Nov 1;167(16):1351-9. doi: 10.1016/j.jplph.2010.05.001. Epub 2010 Jun 1.
Selaginella bryopteris is a lycophyte resurrection plant, which incurves during desiccation and recovers on availability of moisture. The aim of the study was to test and understand the various physiological and biochemical changes the fronds undergo during desiccation and rehydration, to get an insight as to how this plant adapts and survives through the dry phase. Upon desiccation, S. bryopteris fronds showed drastic inhibition in net photosynthesis (A) and maximal photochemical efficiency of PSII (F(v)/F(m)) however, chlorophyll content did not show much variation. Dark respiration (R(d)) continued even at 10% relative water content (RWC), and showed a burst after rehydration, which is proposed to be crucial to establish protection mechanisms. Desiccation caused an enhanced production of reactive oxygen species (ROS) and increased lipid peroxidation. Proline accumulation increased substantially by 11-fold. Sucrose and starch contents decreased upon desiccation as compared to control. The antioxidative enzymes viz. superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) along with soluble acid invertase increased during desiccation. S. bryopteris shows mechanical as well as physiological mechanisms for tolerance to extreme levels of desiccation stress. The rapid and almost complete recovery of F(v)/F(m) after rehydration clearly indicates the absence of marked photoinhibitory or thermal injury to PSII during desiccation. This along with the homoiochlorophyllous characteristics enables S. bryopteris to recover its A. The antioxidant metabolism further plays an important role in the desiccation tolerance of S. bryopteris.
卷柏是一种石松类复苏植物，在干燥时会向内卷曲，在水分充足时会恢复。本研究旨在测试和了解叶片在干燥和复水过程中经历的各种生理和生化变化，以深入了解该植物如何通过干燥阶段适应和生存。在干燥过程中，卷柏叶片的净光合作用（A）和 PSII 的最大光化学效率（F(v)/F(m)）急剧下降，但叶绿素含量变化不大。暗呼吸（R(d)）即使在相对含水量（RWC）为 10%时仍在继续，并在复水后出现爆发，这被认为是建立保护机制的关键。干燥导致活性氧（ROS）产生增加和脂质过氧化加剧。脯氨酸积累增加了 11 倍。与对照相比，干燥后蔗糖和淀粉含量下降。抗氧化酶如超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）和过氧化氢酶（CAT）以及可溶性酸性转化酶在干燥过程中增加。卷柏表现出对极端干燥胁迫的机械和生理耐受机制。复水后 F(v)/F(m)几乎完全恢复，这表明在干燥过程中 PSII 没有明显的光抑制或热损伤。这与同绿叶素的特性一起使卷柏能够恢复其 A。抗氧化代谢在卷柏的干燥耐受性中进一步发挥重要作用。
