Southern Piedmont Research Center, Agricultural Research Service, United States Department of Agriculture, Watkinsville, Georgia 30677.
Plant Physiol. 1973 Nov;52(5):448-52. doi: 10.1104/pp.52.5.448.
A number of plant species were surveyed to obtain pure leaf epidermal tissue in quantity. Commelina communis L. and Tulipa gesnariana L. (tulip) were chosen for further work. Chlorophyll a/b ratios of epidermal tissues were 2.41 and 2.45 for C. communis and tulip, respectively. Phosphoenolpyruvate carboxylase, ribulose-1,5-diphosphate carboxylase, malic enzyme, and NAD(+) and NADP(+) malate dehydrogenases were assayed with epidermal tissue and leaf tissue minus epidermal tissue. In both species, there was less ribulose 1,5-diphosphate than phosphoenolpyruvate carboxylase activity in epidermal tissue whether expressed on a protein or chlorophyll basis whereas the reverse was true for leaf tissue minus epidermal tissue. In both species, malic enzyme activities were higher in epidermal tissue than in the remaining leaf tissue when expressed on a protein or chlorophyll basis. In both species, NAD(+) and NADP(+) malate dehydrogenase activities were higher in the epidermal tissue when expressed on a chlorophyll basis; however, on a protein basis, the converse was true. Microautoradiography of C. communis epidermis and histochemical tests for keto acids suggested that CO(2) fixation occurred predominantly in the guard cells. The significance and possible location of the enzymes are discussed in relation to guard cell metabolism.
对一些植物物种进行了调查，以获得大量的纯叶表皮组织。选择普通鸭跖草和郁金香（郁金香）进行进一步的研究。鸭跖草和郁金香的表皮组织中叶绿素 a/b 比值分别为 2.41 和 2.45。用表皮组织和无表皮组织的叶片组织测定了磷酸烯醇丙酮酸羧化酶、核酮糖-1,5-二磷酸羧化酶、苹果酸酶以及 NAD(+)和 NADP(+)苹果酸脱氢酶的活性。在这两个物种中，无论以蛋白还是叶绿素为基础，表皮组织中核酮糖 1,5-二磷酸的含量均低于磷酸烯醇丙酮酸羧化酶的活性，而无表皮组织的叶片组织则相反。在这两个物种中，无论以蛋白还是叶绿素为基础，表皮组织中的苹果酸酶活性均高于剩余的叶片组织。在这两个物种中，以叶绿素为基础时，表皮组织中的 NAD(+)和 NADP(+)苹果酸脱氢酶活性较高；然而，以蛋白为基础时，情况则相反。普通鸭跖草表皮的微量放射自显影和酮酸的组织化学测试表明，CO2 固定主要发生在保卫细胞中。讨论了这些酶的意义和可能的位置与保卫细胞代谢的关系。
