Vráblíková Hana, McEvoy Maria, Solhaug Knut Asbjørn, Barták Milos, Gauslaa Yngvar
Department of Ecology and Natural Resource Management (Urbygningen), Norwegian University of Life Sciences, P.O. Box 5003, N-1432 As, Norway.
J Photochem Photobiol B. 2006 May 1;83(2):151-62. doi: 10.1016/j.jphotobiol.2005.12.019. Epub 2006 Feb 14.
Seasonal variation in maximal photochemical quantum yield (F(V)/F(M)) of photosystem II (PS II), light adapted quantum yield (Phi(II)) of PS II, non-photochemical quenching (NPQ), contents of chlorophylls, and xanthophyll cycle pigments (VAZ) was studied in Xanthoria parietina repeatedly sampled in one location in S Norway during one year. The seasonal course in the susceptibility to photoinhibition was evaluated as high light-induced changes (1,800 micromol photons m(-2) s(-1) for 24h) in F(V)/F(M), Phi(II), and NPQ, measured as the ability to recover after 2 and 20 h at low light in control thalli with a natural cortical parietin screen, and in thalli from which parietin had been removed prior to high light exposures. F(V)/F(M), Phi(II), chlorophyll content, and the conversion state of VAZ (DEPS) reached minimum in spring. At the same time, yearly maxima of VAZ content and NPQ were recorded. Thereafter, F(V)/F(M), Phi(II), and chlorophyll content increased gradually, reaching maximum values in late autumn. DEPS peaked already in summer. Similarly, VAZ and NPQ decreased from early summer until winter. All data show that the X. parietina photobiont acclimates to seasonal changes in solar radiation, consistent with the lichen's preference for well-lit habitats. However, a comparison with a study of seasonal acclimation in the X. parietina mycobiont shows that in order to understand the seasonal photobiont acclimation, one has to consider the seasonal variation in internal screening caused by the fungal regulation of the PAR-absorbing parietin. A joint effort of both bionts seems to be required to avoid serious photoinhibition.
在挪威南部一个地点对墙黄衣（Xanthoria parietina）进行了为期一年的重复采样，研究了光系统II（PS II）的最大光化学量子产率（F(V)/F(M)）、PS II的光适应量子产率（Phi(II)）、非光化学猝灭（NPQ）、叶绿素含量以及叶黄素循环色素（VAZ）的季节性变化。通过测量在自然皮层含有紫铆素的对照藻体以及在高光暴露前已去除紫铆素的藻体中，在低光下2小时和20小时后恢复的能力，评估了光抑制敏感性的季节性变化过程，即高光诱导的F(V)/F(M)、Phi(II)和NPQ的变化（1800微摩尔光子·平方米⁻²·秒⁻¹，持续24小时）。F(V)/F(M)、Phi(II)、叶绿素含量以及VAZ的转化状态（DEPS）在春季达到最小值。同时，记录到VAZ含量和NPQ的年度最大值。此后，F(V)/F(M)、Phi(II)和叶绿素含量逐渐增加，在深秋达到最大值。DEPS在夏季已经达到峰值。同样，VAZ和NPQ从初夏到冬季逐渐下降。所有数据表明，墙黄衣共生藻适应太阳辐射的季节性变化，这与地衣对光照良好栖息地的偏好一致。然而，与一项关于墙黄衣菌共生体季节性适应的研究比较表明，为了理解共生藻的季节性适应，必须考虑由真菌调节吸收PAR的紫铆素所引起的内部筛选的季节性变化。似乎需要两个共生体的共同努力来避免严重的光抑制。
