Nelso P. Navarro, Pirjo Huovinen, Jocelyn Jofre, Iván Gómez
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引用次数: 0
摘要
研究了紫外线辐射和低温对亚热带鸢尾(Iridaea cordata)鲤鱼孢子的超微结构、光合作用活性(以光系统 II 的最大光化学量子产率 Fv/Fm 度量)、叶绿素-a(Chl-a)含量和紫外线吸收化合物的短期影响。在所有处理中,暴露于光合有效辐射(PAR)和 PAR + 紫外线 4 小时都会引起超微结构的改变。在 2 °C 的 PAR + 紫外线条件下,叶绿体的内部组织被破坏。在暴露于 2 ℃ 的鲤形体中经常发现质球。在 PAR 和 PAR + 紫外线(8 °C)条件下暴露的细胞中首次检测到 "电子致密颗粒",类似于褐藻的藻体。在 PAR + UV(64%)和 PAR(25%)条件下,在 2 °C下暴露 4 小时后,Fv/Fm 下降。在 8 °C时,只有在 PAR + UV条件下,Fv/Fm才下降了21%。经过紫外线处理的鲤鱼孢子在暗光下暴露 4 小时后,光合作用部分恢复。在所有的辐射和温度处理中,紫外线吸收化合物都发生了降解,但在昏暗光照 4 小时后没有恢复。研究表明,虽然虫草鲤孢子具有光保护机制,但紫外线辐射会严重破坏它们的超微结构和生理机能,在低温条件下更会加剧这种破坏。
Temperature Dependence and the Effects of Ultraviolet Radiation on the Ultrastructure and Photosynthetic Activity of Carpospores in Sub-Antarctic Red Alga Iridaea cordata (Turner) Bory 1826
The short-term effects of UV radiation and low temperature on ultrastructure, photosynthetic activity (measured as the maximal photochemical quantum yield of photosystem II: Fv/Fm), chlorophyll-a (Chl-a) contents, and UV-absorbing compounds on the carpospores of Iridaea cordata from a sub-Antarctic population were investigated. Exposure to both photosynthetically active radiation (PAR) and PAR + UV for 4 h caused ultrastructural modifications in all treatments. Under PAR + UV at 2 °C, a disruption of the chloroplast’s internal organization was observed. Plastoglobuli were often found in carpospores exposed to 2 °C. ‘Electron dense particles’, resembling physodes of brown algae, were detected for the first time in cells exposed to PAR and PAR + UV at 8 °C. Fv/Fm decreased following 4 h exposure at 2 °C under PAR + UV (64%) and PAR (25%). At 8 °C, Fv/Fm declined by 21% only under PAR + UV. The photosynthesis of carpospores previously treated with UV partially recovered after a 4 h exposure under dim light. UV-absorbing compounds were degraded in all radiation and temperature treatments without recovery after a 4 h dim light period. Chl-a did not change, whereas total carotenoids increased under PAR at 8 °C The study indicates that although carpospores of I. cordata exhibit photoprotective mechanisms, UV radiation strongly damages their ultrastructure and physiology, which were exacerbated under low temperatures.