UV-B紫外辐射对条斑紫菜生理生化的影响

Effects of UV-B Ultraviolet Radiation on the Physiology and Biochemistry of Pyropia yezoensis

中文关键词: 条斑紫菜  UV-B  光合作用  叶绿素荧光  酪氨酸酶

英文关键词: Pyropia yezoensis  UV-B  Photosynthesis  Chlorophyll fluorescence  Tyrosinase

中文摘要:

      条斑紫菜(Pyropia yezoensis)作为一种生长在潮间带的经济海藻，在适应干露失水时的高紫外辐射上有其独特的特性。本研究以无UV-B辐射为对照组，0.5 W/m2(低)和2 W/m2(高)UV-B辐射为实验组，检测条斑紫菜对UV-B紫外辐射响应的叶绿素荧光光合参数、多光谱荧光参数以及酪氨酸酶活性的变化。结果显示，受到UV-B辐射的条斑紫菜的叶绿素荧光光合参数(QY_max、NPQ_Lss、qP_Lss和Rfd_Lss)随辐照时间呈不同程度的下降趋势，并且高辐射强度下的各光合参数值低于低辐射强度，表明条斑紫菜光合作用受到辐射的负面影响；极早期胁迫参数F440/F690和F440/F740的差异表明，2 W/m2 UV-B辐射组条斑紫菜比0.5 W/m2辐照组更早(1 h)进入胁迫状态，且UV-B辐射下条斑紫菜酚醛类物质减少；与叶绿素浓度呈负相关的参数F690/F740变化表明，0.5 W/m2辐照组叶绿素浓度高于对照组，而在辐照3 h内低于2 W/m2辐照组，2 W/m2辐照组叶绿素浓度则先上升，并在辐照4 h下降，至6 h呈显著降低，说明藻体可耐受较低UV-B辐射，而高UV-B长时间辐照对藻体造成明显的伤害；对酪氨酸酶的活性检测结果表明，受到UV-B辐照的条斑紫菜酪氨酸酶活性显著高于对照组，且高辐照组的酶活性高于低辐照组的酶活性。

英文摘要:

      As an economically important alga growing in the intertidal zone, Pyropia yezoensis has the unique characteristics of adapting to high ultraviolet radiation in the open air and to desiccation conditions. In this experiment, light without UV-B radiation was used as a control, and low UV-B radiation of 0.5 W/m2 and high UV-B radiation of 2 W/m2 were used to detect changes in chlorophyll fluorescence photosynthetic parameters, multi-spectral fluorescence parameters, and tyrosinase activity in response to UV-B ultraviolet radiation in the gametophytes of P. yezoensis. The results showed that the chlorophyll fluorescence photosynthetic parameters (QY_max, NPQ_Lss, qP_Lss, Rfd_Lss) of P. yezoensis under UV-B radiation displayed a gradient decline with irradiation time, and the values of photosynthetic parameters were lower at high radiation intensity (2 W/m2) than at low radiation intensity (0.5 W/m2). The early stress parameters of F440/F690 and F440/F740, which are positively related to secondary metabolites such as phenol or aldehyde concentration, showed that the group under conditions of 2 W/m2 entered a forced state earlier than the group under 0.5 W/m2. Secondary metabolites such as phenol or aldehyde showed concentration declines. F690/F740, which is negatively correlated with chlorophyll concentration, indicated that the chlorophyll concentration under 0.5 W/m2 irradiation was higher than that under no UV-B irradiation, but was lower than the maximum value in the rising period of 2 W/m2 irradiation. The chlorophyll concentration increased initially and then decreased rapidly after 4 h under 2 W/m2, indicating that the chlorophyll concentration is less sensitive to UV-B radiation under low radiation intensity, whereas it is more sensitive under high radiation intensity. The results showed that the tyrosinase activity was significantly higher in P. yezoensis gametophytes irradiated with UV-B than in the control group and that the enzyme activity under 2 W/m2 UV-B was higher than that under 0.5 W/m2 UV-B.