Keller Felix, Matile Philippe
Institute of Plant Biology, University of Zürich, Zollikerstr. 107 CH-8008 Zürich, Switzerland.
New Phytol. 1989 Nov;113(3):291-299. doi: 10.1111/j.1469-8137.1989.tb02406.x.
Mannitol and sucrose are produced photosynthetically in the mesophyll and translocated in the phloem of celery leaves. The thick and fleshy petioles of these leaves act as reversible carbohydrate sinks, storing mainly mannitol, glucose and fructose but very little sucrose (less than 3.3 mg ml sap) in their parenchyma. The concentrations of soluble carbohydrates and the activities of enzymes of sucrose cleavage were asayed in the petiole parenchyma during leaf development. Mannitol (about 20 mg ml sap), glucose and fructose (about 10 to 15 mg ml sap each), changed little with development. Soluble acid invertase accounted for over 95 % of the total enzymic sucrose cleavage measured in vitro. Its activity was closely related to development with a sharp decrease during leaf maturation. With protoplasts from petiole parenchyma and vacuoles isolated from them it was demonstrated that 28% of the total soluble acid invertase of the tissue was in the apoplast and 72 % in the vacuole. Alkaline invertase and sucrose synthase were totally cytosolic. Glucose and fructose, the main storage sugars of these protoplasts, were vacuolar in location, whereas mannitol was both cytosolic (19%) and vacuolar (81%).
甘露醇和蔗糖在叶肉细胞中通过光合作用产生，并在芹菜叶的韧皮部中运输。这些叶子厚实多肉的叶柄充当可逆的碳水化合物库，在其薄壁组织中主要储存甘露醇、葡萄糖和果糖，但蔗糖含量极少（每毫升汁液中少于3.3毫克）。在叶片发育过程中，对叶柄薄壁组织中的可溶性碳水化合物浓度和蔗糖裂解酶的活性进行了测定。甘露醇（约每毫升汁液20毫克）、葡萄糖和果糖（各约每毫升汁液10至15毫克）在发育过程中变化不大。可溶性酸性转化酶占体外测定的总酶促蔗糖裂解量的95%以上。其活性与发育密切相关，在叶片成熟期间急剧下降。利用叶柄薄壁组织的原生质体及其分离出的液泡，证明该组织中总可溶性酸性转化酶的28%存在于质外体中，72%存在于液泡中。碱性转化酶和蔗糖合酶完全位于细胞质中。这些原生质体的主要储存糖葡萄糖和果糖位于液泡中，而甘露醇则同时存在于细胞质（19%）和液泡（81%）中。
