Department of Molecular and Cell Biology, U-42, University of Connecticut, Storrs, Connecticut 06268.
Plant Physiol. 1987 Apr;83(4):856-62. doi: 10.1104/pp.83.4.856.
We investigated H(+) fluxes during circadian rhythmic movements of Samanea saman leaflets by monitoring the pH of a weakly buffered medium bathing extensor or flexor motor tissue excised at different times during 51 hours of darkness. Experiments were made in media of two different osmotic potentials: -0.3 megapascal (control medium) and -1.2 megapascals (control medium supplemented with 0.4 molar mannitol or sorbitol). Both extensor and flexor tissue took up H(+) from the control medium at all times when the initial pH was 5.5. Rates of uptake by the extensor varied rhythmically in phase with the leaflet movement rhythm, whereas rates for the flexor were similar at all times. Addition of 0.4;molar mannitol (or sorbitol) to the medium magnified the amplitude of the rhythm in H(+) uptake and release by extensor tissue and revealed a rhythm with flexor tissue. In the flexor, mannitol promoted H(+) release (or reduced H(+) uptake) at all times. We propose that mannitol reduces flexor cell turgor, and that low turgor activates the H(+) pump. The magnitude and/or direction of pH changes varied with the initial pH of the medium. The pH values after 60 minutes converged to a narrow range, suggesting that cell wall pH might be regulated.
我们通过监测在 51 小时黑暗期的不同时间取自伸展或弯曲运动组织的弱缓冲介质中 pH 值，来研究 Samanea saman 叶片的昼夜节律运动过程中的 H(+)流。在两种不同渗透压的介质中进行了实验：-0.3 兆帕斯卡（对照介质）和-1.2 兆帕斯卡（对照介质中添加 0.4 摩尔甘露醇或山梨醇）。当初始 pH 值为 5.5 时，伸展和弯曲组织在所有时间都从对照介质中吸收 H(+)。伸展组织的吸收速率与叶片运动节律呈节律性变化，而弯曲组织的吸收速率在所有时间都相似。在介质中添加 0.4 摩尔甘露醇（或山梨醇）放大了伸展组织中 H(+)吸收和释放的节律幅度，并揭示了弯曲组织的节律。在弯曲组织中，甘露醇在所有时间都促进 H(+)释放（或减少 H(+)吸收）。我们提出，甘露醇降低了弯曲组织细胞的膨压，而低膨压激活了 H(+)泵。pH 值的变化幅度和/或方向随介质的初始 pH 值而变化。60 分钟后 pH 值收敛到一个狭窄的范围，表明细胞壁 pH 值可能受到调节。
