Iron Availability Modulates the Response of Endosymbiotic Dinoflagellates to Heat Stress
Iron Availability Modulates the Response of Endosymbiotic Dinoflagellates to Heat Stress
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DOI：
10.1111/jpy.13078
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发表时间：
2020-09
影响因子：
2.9
通讯作者：
H. Reich;Wan-chen Tu;I. Rodriguez;Yalan Chou;Elise F. Keister;D. Kemp;T. Lajeunesse;T. Ho
中科院分区：
文献类型：
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作者：
H. Reich;Wan-chen Tu;I. Rodriguez;Yalan Chou;Elise F. Keister;D. Kemp;T. Lajeunesse;T. Ho
变暖和营养限制是已知的削弱微藻健康的压力源。在压力的情况下，获得能量储备可以最大限度地减少生理损伤。由于其在生物化学过程中的广泛需求，铁是一种重要的微量金属，特别是对于光合生物。在经历温度上升的海洋中，铁的可用性降低可能会导致造礁珊瑚的热敏感性，这些珊瑚依赖于与甲藻的共生来生存。为了测试铁浓度对热敏感性的影响，当暴露于升高的温度（26至30°C）和在具有饱和辐射的昼夜光循环下从充满（500 pM Fe '）至限制（50 pM Fe'）的铁浓度时，评估培养的共生甲藻（短鞭藻属;共生藻科）的生理反应。在高温下光合效率的下降表明热胁迫的敏感性。此外，在热应力期间，需要五倍量的铁来达到指数生长（26-28°C下50 pM Fe ′对30°C下250 pM Fe′）。在达到指数生长的处理中，短须草比B.minutum生长更快，可能是由于铁和其他微量金属的细胞含量更高。B.psygmophilum的金属组成仅在最高温度（30°C）下发生变化，而B.minutum的变化在较低温度（28°C）下观察到。铁的可用性在调节每个藻类对热应力的反应中的影响表明了微量金属对珊瑚藻类共生健康的重要性。最终，获得稀有金属的更大能力可能会提高珊瑚对生理压力的耐受性，并有助于与宿主一种共生体物种相关的性能差异。
Warming and nutrient limitation are stressors known to weaken the health of microalgae. In situations of stress, access to energy reserves can minimize physiological damage. Because of its widespread requirements in biochemical processes, iron is an important trace metal, especially for photosynthetic organisms. Lowered iron availability in oceans experiencing rising temperatures may contribute to the thermal sensitivity of reef‐building corals, which rely on mutualisms with dinoflagellates to survive. To test the influence of iron concentration on thermal sensitivity, the physiological responses of cultured symbiotic dinoflagellates (genus Breviolum; family Symbiodiniaceae) were evaluated when exposed to increasing temperatures (26 to 30°C) and iron concentrations ranging from replete (500 pM Fe’) to limiting (50 pM Fe’) under a diurnal light cycle with saturating radiance. Declines in photosynthetic efficiency at elevated temperatures indicated sensitivity to heat stress. Furthermore, five times the amount of iron was needed to reach exponential growth during heat stress (50 pM Fe′ at 26–28°C vs. 250 pM Fe′ at 30°C). In treatments where exponential growth was reached, Breviolum psygmophilum grew faster than B.minutum, possibly due to greater cellular contents of iron and other trace metals. The metal composition of B.psygmophilum shifted only at the highest temperature (30°C), whereas changes in B.minutum were observed at lower temperatures (28°C). The influence of iron availability in modulating each alga’s response to thermal stress suggests the importance of trace metals to the health of coral‐algal mutualisms. Ultimately, a greater ability to acquire scarce metals may improve the tolerance of corals to physiological stressors and contribute to the differences in performance associated with hosting one symbiont species over another.