Complete inactivation of photosynthetic activity during desiccation and rapid recovery by rehydration in the aerial microalga Trentepohlia jolithus.
Complete inactivation of photosynthetic activity during desiccation and rapid recovery by rehydration in the aerial microalga Trentepohlia jolithus.
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DOI：
10.1111/plb.12494
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发表时间：
2016-11
期刊：
影响因子：
3.9
通讯作者：
L. Zhang;Y. Li;J. Liu
中科院分区：
文献类型：
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作者：
L. Zhang;Y. Li;J. Liu
气生微藻更容易暴露在恶劣和迅速变化的环境条件下，包括干燥和辐射。在强光下，处于干燥状态的气生藻类极易受到光损伤。因此，气生藻类需要有效的保护机制来耗散多余的激发能。在这项研究中，在干燥过程中的光合行为的变化，并在Trentepohlia jolithus复水后，证实了使用叶绿素a荧光（OJIP）瞬态，允许确定的光保护机制，这种气生植物。T.与100%和87%RH下的细胞相比，25%相对空气湿度（RH）下的jolithus细胞显著收缩，减少了用于光吸收的表面积。在25%RH下，OJIP瞬态的形状和强度消失，但在再水化5 s后迅速恢复到100%RH下的水平。与100%RH相比，25%RH条件下PSII的最大量子产额（φPo）、唯象吸收能通量（ABS/CSm）和PSII活性反应中心（RC）均显著降低，吸收比能通量（ABS/RC）显著增加，而俘获比能通量（TRo/RC）无明显变化。在25%RH下，这些参数在再水化5 s后迅速恢复到100%RH下的水平。这些结果表明，在干旱胁迫下，光系统Ⅱ的光吸收效率和光系统Ⅱ RCs的活性可逆地下调。jolithus，这可能是一个特殊的适应机制，生存的栖息地快速变化的水的可用性的气生微藻。
Aerial microalgae are more exposed to harsh and rapidly changing environmental conditions, including desiccation and radiation. Under high light, aerial algae in the desiccated state would be highly subject to photodamage. Therefore, aerial algae need effective protective mechanisms to dissipate excess excitation energy. In this study, the changes in photosynthetic behaviors during desiccation and after rehydration in Trentepohlia jolithus were confirmed using chlorophyll a fluorescence (OJIP) transient, allowing determination of the photoprotection mechanisms of this aerial alga. The filaments of T. jolithus cells at 25% relative air humidity (RH) are significantly shrunken compared with those at 100% and 87% RH, decreasing the surface area for light absorption. At 25% RH, the shape and intensity of the OJIP transient disappeared, but recovered rapidly to the level at 100% RH after 5 s of rehydration. Compared with 100% RH, the maximum quantum yield of PSII (φPo ), phenomenological energy fluxes for absorption (ABS/CSm) and active PSII reaction centers (RCs) at 25% RH decreased significantly, the specific energy fluxes for absorption (ABS/RC) increased significantly, but the specific energy fluxes for trapping (TRo/RC) at 25% RH did not change. These parameters at 25% RH recovered rapidly to the level at 100% RH after 5 s of rehydration. These results suggest that the efficiency of PSII light absorption and activities of PSII RCs were reversibly down-regulated in desiccated T. jolithus, which may be a special adaptive mechanism for the survivability of aerial microalgae in habitats with rapidly changing water availability.