Barták Milos, Solhaug Knut Asbjørn, Vráblíková Hana, Gauslaa Yngvar
Department of Plant Physiology and Anatomy, Masaryk University, Kotlarska 2, 61137, Brno, Czech Republic.
Oecologia. 2006 Oct;149(4):553-60. doi: 10.1007/s00442-006-0476-2. Epub 2006 Jun 28.
This study aims to assess the photoprotective potential of desiccation-induced curling in the light-susceptible old forest lichen Lobaria pulmonaria by using chlorophyll fluorescence imaging. Naturally curled thalli showed less photoinhibition-induced limitations in primary processes of photosynthesis than artificially flattened specimens during exposures to 450 micromol m-2 s-1 in the laboratory after both 12- (medium dose treatment) and 62-h duration (high dose treatment). Thallus areas shaded by curled lobes during light exposure showed unchanged values of measured chlorophyll fluorescence parameters (FV/FM, PhiPS II), whereas non-shaded parts of curled thalli, as well as the mean for the entire flattened thalli, showed photoinhibitory limitation after light treatments. Furthermore, the chlorophyll fluorescence imaging showed that the typical small-scale reticulated ridges on the upper side of L. pulmonaria caused a spatial, small-scale reduction in damage due to minor shading. Severe dry-state photoinhibition readily occurred in flattened and light-treated L. pulmonaria, although the mechanisms for such damage in a desiccated and inactive stage are not well known. Natural curling is one strategy to reduce the chance for serious photoinhibition in desiccated L. pulmonaria thalli during high light exposures.
本研究旨在通过叶绿素荧光成像评估干燥诱导卷曲对光敏感的老龄森林地衣肺衣（Lobaria pulmonaria）的光保护潜力。在实验室中，将自然卷曲的叶状体暴露于450微摩尔·平方米⁻²·秒⁻¹光照下12小时（中等剂量处理）和62小时（高剂量处理）后，与人工展平的标本相比，自然卷曲的叶状体在光合作用初级过程中受光抑制诱导的限制较小。光照期间被卷曲裂片遮挡的叶状体区域，其测量的叶绿素荧光参数（FV/FM、PhiPS II）值未发生变化，而卷曲叶状体未被遮挡的部分以及整个展平叶状体的平均值在光照处理后显示出光抑制限制。此外，叶绿素荧光成像显示，肺衣上侧典型的小规模网状脊由于轻微遮光导致空间上小规模的损伤减少。在展平且经光照处理的肺衣中很容易发生严重的干燥状态光抑制，尽管在干燥和无活性阶段这种损伤的机制尚不清楚。自然卷曲是一种减少高光暴露期间干燥的肺衣叶状体发生严重光抑制几率的策略。
