The effect of temperature, light‐spectrum, desiccation and salinity gradients on the photosynthetic performance of a subtidal brown alga, Sargassum macrocarpum, from Japan
The effect of temperature, light‐spectrum, desiccation and salinity gradients on the photosynthetic performance of a subtidal brown alga, Sargassum macrocarpum, from Japan
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DOI：
10.1111/pre.12508
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发表时间：
2022-12
影响因子：
1.5
通讯作者：
Tomohiro Ito;Toui Yoshioka;Hiromori Shimabukuro;Gregory N. Nishihara;H. Endo;Ryuta Terada
中科院分区：
文献类型：
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作者：
Tomohiro Ito;Toui Yoshioka;Hiromori Shimabukuro;Gregory N. Nishihara;H. Endo;Ryuta Terada
利用脉冲调幅-叶绿素荧光仪和溶解氧传感器，研究了温度、光谱、干燥和盐度梯度对日本亚潮下褐藻马尾藻光合作用的影响。在培养6天(4-36℃)时，最大量子产量(黑暗中的Fv/Fm)和有效量子产量(ΔF/Fm‘，50μ−光子m−2 SΦ1；=PPSⅡ)的温度响应在12-28℃时保持较高的水平，但在较高温度下会下降。然而，ΔF/Fm‘在低于8°C的温度下也下降了，这表明在低温下的光敏感度，因为Fv/Fm仍然很高。24℃下红光(660 Nm)、绿光(525 Nm)、蓝光(450 Nm)和白光(金属卤化物灯)下的光合作用-辐射响应表明，蓝光和白光下的最大净光合量大于红光和绿光下的最大净光合量，表明蓝光在潮下光环境中的敏感性和光合作用的有效性。在干燥实验中，样品在24°C和50%湿度的暗光下暴露8h后，ΔF/Fm‘在超过45min后迅速下降，而且ΔF/Fm’即使在海水中复水1d也未能恢复到初始水平。在复现状态下，当相对含水率大于50%时，ΔF/Fm‘保持在较高水平；相反，当相对含水率小于50%时，Fm/Fm’迅速下降。当相对含水量降低到50%以下时，无论随后的复水作用如何，ΔF/Fm‘都没有恢复到初始水平，这表明光合作用从干燥中恢复的能力很低。当盐度超过20-40PSU时，ΔF/Fm‘下降，培养3天的光合作用具有明显的狭盐响应。对日本温带水域潮下环境的适应可能与这些特征有关。
The effect of temperature, light‐spectrum, desiccation and salinity gradients on the photosynthesis of a Japanese subtidal brown alga, Sargassum macrocarpum (Fucales), was determined using a pulse amplitude modulation‐chlorophyll fluorometer and dissolved oxygen sensors. Temperature responses of the maximum (Fv/Fm in darkness) and effective (ΔF/Fm′ at 50 μmol photons m−2 s−1; = ΦPSII) quantum yields during 6‐day culture (4–36°C) remained high at 12–28°C, but decreased at higher temperatures. Nevertheless, ΔF/Fm′ also dropped at temperatures below 8°C, suggesting light sensitivity under chilling temperatures because Fv/Fm remained high. Photosynthesis–irradiance responses at 24°C under red (660 nm), green (525 nm), blue (450 nm) and white light (metal halide lamp) showed that maximum net photosynthesis under blue and white light was greater than under red and green light, indicating the sensitivity and photosynthetic availability of blue light in the subtidal light environment. In the desiccation experiment, samples under aerial exposure of up to 8 h under dim‐light at 24°C and 50% humidity showed that ΔF/Fm′ quickly declined after more than 45 min of emersion; furthermore, ΔF/Fm′ also failed to recover to initial levels even after 1 day of rehydration in seawater. Under the emersion state, the ΔF/Fm′ remained high when the relative water content (RWC) was greater than 50%; in contrast, it quickly dropped when the RWC was less than 50%. When the RWC was reduced below 50%, ΔF/Fm′ did not return to initial levels, regardless of subsequent re‐hydration, suggesting a low capacity of photosynthesis to recover from desiccation. The stenohaline response of photosynthesis under 3‐day culture is evident, given that ΔF/Fm′ declined when salinity was beyond 20–40 psu. Adaptation to subtidal environments in temperate waters of Japan can be linked to these traits.