Talbott Lawrence D, Hammad Jamila W, Harn Lucy Cien, Nguyen Vi Hai, Patel Jaynita, Zeiger Eduardo
Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 90024, USA.
Plant Cell Physiol. 2006 Mar;47(3):332-9. doi: 10.1093/pcp/pci249. Epub 2006 Jan 17.
Green light reversal of blue light-stimulated stomatal opening was discovered in isolated stomata. The present study shows that the response also occurs in stomata from intact leaves. Arabidopsis thaliana plants were grown in a growth chamber under blue, red and green light. Removal of the green light opened the stomata and restoration of green light closed them to baseline values under experimental conditions that rule out a mesophyll-mediated effect. Assessment of the response to green light over a daily time course showed that the stomatal sensitivity to green light was observed only in the morning, which coincided with the use of potassium as a guard cell osmoticum. Sensitivity to green light was absent during the afternoon phase of stomatal movement, which was previously shown to be dominated by sucrose osmoregulation in Vicia faba. Hence, the shift away from potassium-based osmoregulation in guard cells is further postulated to entail a shift from blue light to photosynthesis as the primary component of the stomatal response to light. Stomata from intact leaves of the zeaxanthin-less, npq1 mutant of Arabidopsis failed to respond to the removal or restoration of green light in the growth chamber, or to short, high fluence pulses of blue or green light. These data confirm previous studies showing that npq1 stomata are devoid of a specific blue light response. In contrast, stomata from intact leaves of phot1 phot2 double mutant plants had a reduced but readily detectable response to the removal of green light and to blue and green pulses.
在分离的气孔中发现了蓝光刺激气孔开放的绿光逆转现象。本研究表明，完整叶片中的气孔也会出现这种反应。拟南芥植株在生长室中分别在蓝光、红光和绿光下生长。在排除叶肉介导效应的实验条件下，去除绿光会使气孔开放，恢复绿光则使其关闭至基线值。对一天中绿光反应的评估表明，气孔对绿光的敏感性仅在早晨观察到，这与保卫细胞将钾作为渗透剂的情况一致。在气孔运动的下午阶段，对绿光不敏感，此前已表明蚕豆气孔运动的下午阶段主要由蔗糖渗透调节主导。因此，进一步推测保卫细胞中基于钾的渗透调节的转变意味着气孔对光反应的主要成分从蓝光转变为光合作用。拟南芥无玉米黄质的npq1突变体完整叶片的气孔在生长室中对绿光的去除或恢复没有反应，对蓝光或绿光的短时间、高辐照度脉冲也没有反应。这些数据证实了之前的研究，即npq1气孔缺乏特定的蓝光反应。相比之下，phot1 phot2双突变体植株完整叶片的气孔对绿光去除以及蓝光和绿光脉冲的反应有所减弱，但仍易于检测到。
