紫外辐射对条斑紫菜不同部位藻体光化学效率和光合色素含量的影响

摘要

实验室条件下研究了紫外辐射(UVR)对条斑紫菜藻体不同部位最大光化学效率(Fv/Fm)和光合色素含量的影响,以探讨条斑紫菜不同部位对紫外辐射反应的差异性.在全光谱PAB(PAR+UV-A+UV-B,280～700 nm)和滤除紫外辐射UVR(UV-A+UV-B)的有效光辐射(PAR,395～700 nm)两种处理下进行测定.实验结果表明,PAB处理后的各部位藻体最大光化学效率下降程度均高于PAR处理后,且弱光期恢复程度低、速度慢.藻体不同部位间最大光化学效率下降程度也存在差异,藻体梢部对PAB的耐受性高,恢复也较快;基部耐受性最差,恢复也较慢.藻红蛋白(phycoerythrin,PE)和藻蓝蛋白(phycocyanin,PC)对不同辐射处理较敏感,PAB辐射处理后,各藻体部位的PE、PC含量均显著上升(P＜0.05),其中藻体梢部PAB处理后的PE、PC含量的均极显著升高(P＜0.01).然而不同部位藻体在PAB和PAR照射下,叶绿素a(Chl.a)和类胡萝卜素(Car)并无显著变化(P＞0.05).藻体的紫外吸收物质(MAAs)的含量从基部到梢部逐步升高,不同辐射处理前后,各藻体部位的紫外吸收物质也未显著增加(P＞0.05).总之,条斑紫菜不同部位藻体光合生理特性存在较大差异.推测条斑紫菜应对紫外辐射的策略有遮蔽作用,积累紫外吸收物质和动态光抑制作用.%In this study, the amount of damage to Porphyra yezoensis by ultraviolet radiation ( UVR ) was assessed by analyzing the photochemical efficiency and pigment concentration between different blade parts under laboratory conditions. All parts of the blade were exposed to either PAB( PAR + UV- A + UV- B)(280 - 700 nm) a full spectrum or partial PAR ( 395 - 700 nm) spectrum using cut-off glass filters. It was observed that PAB caused a more significant decrease in the optimal photochemical efficiency than PAR in all blade parts, followed by a lower recovery toward the initial values. Marked differences of the optimal photochemical efficiency between all parts of blade under UV exposure were observed. Apical parts were more resistant but had quicker recovery, basal parts were more sensitive to PAB and had slower recovery.After different radiation treatment, phycoerythrin (PE)and phycocyanin (PC)are more sensitive to PAB treatment and increased significantly in all parts of blade. The PE and PC contents of apical parts had extreme increase,while no remarkable differences of Chlorophyll a and carotenoid were observed. Determination of mycosporine-like amino acids (MAAs)before and during exposure to solar simulated irradiation showed no remarkable differences. The MAAs contents increased from basal to apical parts. Above all, the different parts of Porphyra yezoensis displayed bigger dissimilarity in the photosynthetic physiology characteristics. We presumed that the strategies to cope with UV radiation may including sheltering effect, accumulateing UV absorbing substance and dynamic photoinhibition.