Mott Keith A, Berg David G, Hunt Sean M, Peak David
Biology Department, Utah State University, Logan, UT, 84322-5305, USA.
Plant Cell Environ. 2014 May;37(5):1184-91. doi: 10.1111/pce.12226. Epub 2013 Dec 8.
Previous studies have suggested that the red light and CO2 responses of stomata are caused by a signal from the mesophyll to the guard cells. Experiments were conducted to test the idea that this signal is a vapour-phase ion. Stomata in isolated epidermes of Tradescantia pallida were found to respond to air ions created by an electrode that was positioned under the epidermes. Anthocyanins in the epidermes of this species were observed to change colour in response to these air ions, and this change in colour was attributed to changes in pH. A similar change in lower epidermal colour was observed in intact leaves upon illumination and with changes in CO2 concentration. Based on the change in epidermal colour, the pH of the epidermis was estimated to be approximately 7.0 in darkness and 6.5 in the light. Stomata in isolated epidermes responded to pH when suspended over (but not in contact with) solutions of different pH. We speculate that stomatal responses to CO2 and light are caused by vapour-phase ions, possibly hydronium ions that change the pH of the epidermis.
先前的研究表明，气孔对红光和二氧化碳的反应是由叶肉向保卫细胞发出的信号引起的。进行了实验以验证这一信号是气相离子的观点。发现在紫露草离体表皮中的气孔对置于表皮下方的电极产生的空气离子有反应。观察到该物种表皮中的花青素会因这些空气离子而变色，且这种颜色变化归因于pH值的变化。在完整叶片中，光照和二氧化碳浓度变化时，下表皮颜色也有类似变化。根据表皮颜色变化，估计表皮在黑暗中的pH值约为7.0，在光照下为6.5。离体表皮中的气孔悬浮在（但不接触）不同pH值的溶液上方时会对pH值产生反应。我们推测，气孔对二氧化碳和光照的反应是由气相离子引起的，可能是改变表皮pH值的水合氢离子。
