Analyses of a Gravistimulation-Specific Ca2+ Signature in Arabidopsis using Parabolic Flights
Analyses of a Gravistimulation-Specific Ca2+ Signature in Arabidopsis using Parabolic Flights
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DOI：
10.1104/pp.113.223313
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发表时间：
2013-10-01
期刊：
影响因子：
7.4
通讯作者：
Tatsumi, Hitoshi
中科院分区：
文献类型：
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作者：
Toyota, Masatsugu;Furuichi, Takuya;Tatsumi, Hitoshi
重力是影响地球上生物形态和功能的关键环境因素。植物感知重力矢量的变化（重力刺激）并相应地调节其生长方向。在拟南芥 (Arabidopsis thaliana) 幼苗中，通过在 1g 地球环境下旋转样本来实现重力刺激，已知会诱导细胞质钙浓度 ([Ca2+](c)) 的双相（瞬时和持续）增加。然而，尚未确定真正由重力刺激引起的 [Ca2+](c) 增加，因为重力刺激通常伴随着标本在地面上的旋转 (1g)，为治疗增加了额外的机械信号。在这里，我们通过使用抛物线飞行提供的微重力（小于 10(-4) g）条件将旋转与重力刺激分开，展示了拟南芥幼苗中重力刺激特异性的 Ca2+ 反应。不旋转标本的重力刺激导致 [Ca2+](c) 持续增加，这与地面实验中观察到的第二次持续 [Ca2+](c) 增加密切相关。在各种重力强度（例如0.5g、1.5g或2g）下结合超重力和微重力之间的快速切换分析了[Ca2+](c)的增加，表明拟南芥幼苗具有非常快速的重力感应机制，可以在亚秒时间尺度上将大范围的重力变化（0.5g-2g）线性转换为Ca2+信号。
Gravity is a critical environmental factor affecting the morphology and functions of organisms on the Earth. Plants sense changes in the gravity vector (gravistimulation) and regulate their growth direction accordingly. In Arabidopsis (Arabidopsis thaliana) seedlings, gravistimulation, achieved by rotating the specimens under the ambient 1g of the Earth, is known to induce a biphasic (transient and sustained) increase in cytoplasmic calcium concentration ([Ca2+](c)). However, the [Ca2+](c) increase genuinely caused by gravistimulation has not been identified because gravistimulation is generally accompanied by rotation of specimens on the ground (1g), adding an additional mechanical signal to the treatment. Here, we demonstrate a gravistimulation-specific Ca2+ response in Arabidopsis seedlings by separating rotation from gravistimulation by using the microgravity (less than 10(-4) g) conditions provided by parabolic flights. Gravistimulation without rotating the specimen caused a sustained [Ca2+](c) increase, which corresponds closely to the second sustained [Ca2+](c) increase observed in ground experiments. The [Ca2+](c) increases were analyzed under a variety of gravity intensities (e. g. 0.5g, 1.5g, or 2g) combined with rapid switching between hypergravity and microgravity, demonstrating that Arabidopsis seedlings possess a very rapid gravity-sensing mechanism linearly transducing a wide range of gravitational changes (0.5g-2g) into Ca2+ signals on a subsecond time scale.