光强调控三角褐指藻对海洋酸化的生理学响应

光和海洋酸化(CO₂浓度升高)分别对海洋硅藻的光合能力具有不同程度的影响, 但两者的耦合响应被较少关注。研究以三角褐指藻作为实验材料, 测定了不同光强下CO₂浓度升高对三角褐指藻的生长、净光合速率、生化组分、胞外碳酸酐酶(eCA)活性和核酮糖-1,5-二磷酸羧化/氧化酶(Rubisco)活性的影响。结果显示在低光下, CO₂浓度对三角褐指藻的生长和净光合速率(P_n)并没有显著影响, 而在高光下, 具有明显的影响。无论是在高光或是低光下, eCA活性、叶绿素和可溶性蛋白的含量都随着CO₂浓度的升高而降低。在低光下, 高浓度CO₂ (HC)培养下的Rubisco活性分别是低浓度CO₂ (LC)和中浓度CO₂ (MC)的2.42和1.39倍, 而在高光下, HC培养下的Rubisco活性分别是LC和MC的6.72和3.45倍。以上结果表明硅藻能够通过调节光合生理特征和CCM运行中能量的分配来适应环境中光强和CO₂浓度的变化。

LIGHT-MODULATED PHYSIOLOGICAL RESPONSE TO OCEAN ACIDIFICATION IN PHAEODACTYLUM TRICORNUTUM

There is increasing evidence that different light intensities or ocean acidification (OA) induced by elevated atmospheric CO₂ concentration can affect the photosynthetic capacity of marine diatom to different degrees, respectively however, little attention had been paid to their interaction on diatom. In this study, the growth rate, net photosynthetic rate (P_n), biochemical composition, extracellular carbonic anhydrase (eCA) activity, and Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubiscO) activity were investigated when Phaeodactylum tricornutum was grown under different light intensities and CO₂ concentrations. The results showed that the specific growth rates and P_n in P. tricornutum were not significantly affected by CO₂ concentration under low light intensity (LL), whereas in presence of the high light intensity (HL), elevated CO₂ concentration was beneficial to promote the increase of the rate of P_n. The eCA activity, chlorophyll content, and soluble protein content decreased with increase of CO₂ concentration, regardless of the high or low light. Under LL, RubiscO activity of HC-grown algae was 2.42 and 1.39 times higher than that of LC- or Medium-CO₂ (MC)-grown ones. However, RubiscO activity of HC-grown algae was 6.72 and 3.45 times greater than that of LC- or MC-grown ones under high light. These results indicate that the algae can adapt to changes of light intensity and CO₂ concentrations in the environment by adjusting the allocation of energy during the operation of the CO₂-concentrating mechanism and photosynthesis.