Effects of solar UV-B radiation on canopy structure of Ulva communities from southern Spain
Effects of solar UV-B radiation on canopy structure of Ulva communities from southern Spain
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DOI：
10.1093/jxb/erf091
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发表时间：
2002-12-01
影响因子：
6.9
通讯作者：
Breeman, AM
中科院分区：
文献类型：
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作者：
Bischof, K;Peralta, G;Breeman, AM
在加的斯湾隐蔽的小溪中，乌尔瓦菌形成了延伸的席状树冠。在田间试验中，研究了太阳紫外线辐射对西班牙南部圆叶树光合活性、光合和叶黄素循环色素组成、RubisCO、伴侣蛋白60 （cpn60）含量以及DNA损伤诱导的影响。从自然群落收集的样本被筛选过滤器覆盖，产生不同的辐射条件。在日周期中，单个菌体对天然太阳辐射表现出光抑制作用。这种抑制作用在仅暴露于光合有效辐射（PAR）的样品中更为明显。在这些样品中强烈增加的热耗散表明参与动态光抑制的调节机制的活性。UV-B辐射对光合作用的不利影响仅在高PAR水平下观察到，这表明两个波长范围的协同效应。暴露于PAR+UV-A或不暴露于UV-B+UVA的样品，在一天中没有发现光合量子产率的抑制。在自然地点，席状树冠的顶层通常完全漂白。人工设计的Ulva冠层在自然太阳辐射条件下表现出顶层的快速漂白，而在屏蔽UV或PAR的冠层中没有观察到这种情况。漂白的第一层冠层作为选择性UV- b过滤器，从而防止冠下菌体暴露于有害辐射。冠层内不同位置菌体的光合活性、色素组成和RubisCO浓度的差异证实了这一点。此外，紫外线照射下应激蛋白CPN 60的诱导和DNA损伤的低积累表明存在针对有害UV- b的生理保护机制。提出了在田间条件下uv - b诱导的光合作用抑制机理。
Within the sheltered creeks of Cadiz bay, Ulva thalli form extended mat-like canopies. The effect of solar ultraviolet radiation on photosynthetic activity, the composition of photosynthetic and xanthophyll cycle pigments, and the amount of RubisCO, chaperonin 60 (CPN 60), and the induction of DNA damage in Ulva aff. rotundata Bliding from southern Spain was assessed in the field. Samples collected from the natural community were covered by screening filters, generating different radiation conditions. During daily cycles, individual thalli showed photoinhibitory effects of the natural solar radiation. This inhibition was even more pronounced in samples only exposed to photosynthetically active radiation (PAR). Strongly increased heat dissipation in these samples indicated the activity of regulatory mechanisms involved in dynamic photoinhibition. Adverse effects of UV-B radiation on photosynthesis were only observed in combination with high levels of PAR, indicating the synergistic effects of the two wavelength ranges. In samples exposed either to PAR+UV-A or to UV-B+UVA without PAR, no inhibition of photosynthetic quantum yield was found in the course of the day. At the natural site, the top layer of the mat-like canopies is generally completely bleached. Artificially designed Ulva canopies exhibited fast bleaching of the top layer under the natural solar radiation conditions, while this was not observed in canopies either shielded from UV or from PAR. The bleached first layer of the canopies acts as a selective UV-B filter, and thus prevents subcanopy thalli from exposure to harmful radiation. This was confirmed by the differences in photosynthetic activity, pigment composition, and the concentration of RubisCO in thalli with different positions within the canopy. In addition, the induction of the stress protein CPN 60 under UV exposure and the low accumulation of DNA damage indicate the presence of physiological protection mechanisms against harmful UV-B. A mechanism of UV-B-induced inhibition of photosynthesis under field conditions is proposed.