Assmann S M, Zeiger E
Department of Biological Sciences, Stanford University, Stanford, California 94305.
Plant Physiol. 1985 Feb;77(2):461-4. doi: 10.1104/pp.77.2.461.
A role of the guard cell chloroplasts in the CO(2) response of stomata was investigated through a comparison of the leaf gas exchange characteristics of two closely related orchids: Paphiopedilum harrisianum, which lacks guard cell chloroplasts and Phragmipedium longifolium, which has chlorophyllous guard cells. Leaves of both species had an apparent quantum yield for assimilation of about 0.05, with photosynthesis saturating at 0.300 to 0.400 millimoles per square meter per second. CO(2) curves were obtained by measuring steady-state assimilation and stomatal conductance under 0.180 or 0.053 millimoles per square meter per second white light, or darkness, at 0 to 400 microliters per liter ambient CO(2). The response of assimilation to changes in CO(2) was similar in the two species, but the response of conductance was consistently weaker in Paphiopedilum than in Phragmipedium. The data suggest involvement of guard cell chloroplasts in the stomatal response to CO(2) and in the coupling of assimilation and conductance in the intact leaf.
通过比较两种近缘兰花的叶片气体交换特征，研究了保卫细胞叶绿体在气孔对二氧化碳响应中的作用：一种是缺乏保卫细胞叶绿体的哈氏兜兰（Paphiopedilum harrisianum），另一种是具有含叶绿素保卫细胞的长叶杓兰（Phragmipedium longifolium）。两种植物的叶片同化作用的表观量子产率约为0.05，光合作用在每秒每平方米0.300至0.400毫摩尔时达到饱和。通过在0至400微升/升的环境二氧化碳浓度下，于每秒每平方米0.180或0.053毫摩尔的白光或黑暗条件下测量稳态同化作用和气孔导度，获得了二氧化碳曲线。两种植物同化作用对二氧化碳变化的响应相似，但兜兰的导度响应始终比杓兰弱。数据表明保卫细胞叶绿体参与了气孔对二氧化碳的响应以及完整叶片中同化作用和导度的耦合。
