Effects of light and temperature on the photosynthetic pathway and antioxidant function of two green tide species
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摘要: 绿潮是潮间带绿藻大量增殖形成的高生物量生态灾害,其暴发不仅受到温度、营养盐等环境因素的驱动,而且与自身光合能力的强弱密切相关。本研究以绿潮物种—肠浒苔(Ulva intestinalis)和Ulva expansa为研究对象,通过室外培养实验,检测了它们在夏季高温、高光强条件下的光合途径与抗氧化生理特征,并分析了与光合产物的对应关系。研究结果表明,肠浒苔与U. expansa的光合途径与抗氧化能力存在显著差异。前者的C4光合途径关键酶活性在光合作用过程中出现高表达特征,与光、温度存在显著相关性,C3光合途径关键酶活性在中午受到强光抑制;组织δ13C的变化范围为−17.1‰~−15.7‰,表明其光合作用可能由C3和C4途径共同参与。后者的C4光合途径关键酶活性表达较弱,且与光、温度不存在显著相关性,C3光合途径关键酶活性没有出现明显的光抑制现象;组织δ13C的范围为−23.5‰~−21.9‰,表明其光合作用主要依靠C3途径进行。此外,肠浒苔在培养过程中表现出了较强的抗氧化能力,可能与其在高温、高光强条件下启动C4光合途径密切相关。肠浒苔与U. expansa的比较研究说明,藻类C4光合途径存在显著种间差异性。
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关键词:
- 肠浒苔 /
- Ulva expansa /
- 卡尔文循环 /
- Hatch-Slack光合途径 /
- 光合固碳
Abstract: Green tide is a high biomass ecological disaster caused by the proliferation of green algae in intertidal zone. Its outbreak is not only driven by environmental factors such as temperature and nutrients, but also closely related to its own photosynthetic capacity. In this study, Ulva intestinalis and Ulva expansa, the two green tide species, were selected for the outdoor culture experiment. The photosynthetic pathway, antioxidant physiological characteristics and their corresponding relationship with photosynthetic products of the two species were detected and compared under the conditions of high temperature and high light intensity in summer. The results showed that there were significant differences in photosynthetic pathway and antioxidant capacity between U. intestinalis and U. expansa. The key enzyme activity of C4 photosynthetic pathway was highly expressed in the process of photosynthesis of the former, which was significantly correlated with light and temperature. The key enzyme activity of C3 photosynthetic pathway of U. intestinalis was inhibited by strong light at noon, and the change range of δ13C in tissue ranged from −17.1‰ to −15.7‰, which indicated that C3 and C4 pathway might be involved in its photosynthetic cooperation. For U. expansa, the expression of key enzymes in C4 photosynthetic pathway was weak and there was no significant correlation with light and temperature. Also, there was no obvious photoinhibition in C3 photosynthetic pathway and the range of δ13C in tissue is from −23.5‰ to −21.9‰, indicating that the photosynthesis mainly depends on C3 pathway. In addition, U. intestinalis showed a strong antioxidant capacity in the process of culture, which may be closely related to its C4 photosynthetic pathway under high temperature and high light conditions. The comparative study between U. intestinalis and U. expansa showed that there were significant differences in the initiation of C4 photosynthetic pathway between algal species, and the comparative study on the photosynthetic mechanism of different green algal species needs further exploration. -
图 2 两种绿藻C3关键酶(Rubisco)与C4关键酶(PEPCase、PEPCKase)活性的日变化特征比较
*表示两个物种之间酶活性具有显著性差异,误差棒上的不同小写字母(a, b, c)表示同一物种在不同时间下酶活性有显著性差异(p<0.05)
Fig. 2 The comparison of diurnal variations of C3 key enzyme (Rubisco) and C4 key enzyme (PEPCase and PEPCKase) activities between U. intestinalis and U. expansa
*represents there is a significant difference in enzyme activity between the two species. Different lowercase letters (a, b, c) on the error bars indicate that the same species has a significant difference (p<0.05) in enzyme activity at different times
图 4 两种绿藻抗氧化物酶(SOD、POD)活性和MDA含量的日变化特征比较
*表示两个物种之间酶活性具有显著性差异,误差棒上的不同小写字母(a, b, c)表示同一物种在不同时间下酶活性有显著性差异(p<0.05)
Fig. 4 The comparison of antioxidant enzymes (SOD, POD) actirities and MDA content between U. intestinalis and U. expansa, corresponding to diurnal variations
*represents there is a significant difference in enzyme activity between the two species. Different lowercase letters (a, b, c) on the error bars indicate that the same species has a significant difference (p<0.05) in enzyme activity at different times
表 1 两种绿藻光合作用酶活性与温度、光强的相关性
Tab. 1 Correlations between photosynthetic enzyme activities of U. intestinalis and U. expansa vs. temperature and light intensity
参数 肠浒苔 U. expansa 温度 光强 温度 光强 Rubisco 0.080 0.118 0.700** 0.396 PEPCase 0.429 −0.048 0.068 0.458 PEPCKase 0.688** 0.590* −0.648** −0.515* 注:**表示在0.01水平(双侧)上显著相关;*表示在0.05水平(双侧)上显著相关。 表 2 两种绿藻的抗氧化酶(SOD,POD)活性以及MDA含量与温度、光强的相关性
Tab. 2 Correlation between antioxidase activities, MDA content of U. intestinalis and U. expansa vs. temperature and light intensity
参数 肠浒苔 U. expansa 温度 光强 温度 光强 SOD 0.578* 0.825** 0.277 0.432 POD 0.171 −0.210 0.296 0.368 MDA 0.561* 0.627** 0.390 0.145 注:**表示在0.01水平(双侧)上显著相关;*表示在0.05水平(双侧)上显著相关。 -
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