Physiological and biochemical studies on carbohydrate accumulation of petals cells in major ornamental plants

开花过程中，可溶性碳水化合物大量积累，表明可溶性碳水化合物在植物细胞中起着重要的渗透作用。本研究测定了玫瑰花瓣细胞质、液泡和外质体中的碳水化合物浓度，并与总渗透势和碳水化合物产生的渗透势进行了比较。采用非水分馏法和浸润离心法，建立了花瓣中亚细胞碳水化合物分布的评价方法。用电镜观察花瓣细胞亚细胞区室的体积。随着花瓣的开放，细胞质、液泡和外质体中葡萄糖和果糖的浓度急剧增加。随着花瓣开放，共塑溶液和外塑溶液中的总渗透势增加。总渗透势与碳水化合物源性渗透势的比较表明，总渗透势随花瓣开放的增加主要归因于碳水化合物源性渗透势的增加。因此，液泡中碳水化合物的积累似乎有助于细胞扩张，导致花瓣开放。为了明确碳水化合物是否在液泡中积累，研究了金鱼龙、飞燕草、桔梗、凤尾莲、龙胆等花的细胞质、液泡和外质体中碳水化合物的分布。金鱼龙中葡萄糖和果糖含量，飞燕草中葡萄糖、果糖和甘露醇含量，桔梗中蔗糖和葡萄糖含量，杜鹃中葡萄糖和2- c -甲基赤藓糖醇含量，金盏花中龙胆糖和蔗糖含量随着花瓣开放而增加。这些碳水化合物主要分布在液泡中。在这些花中，液泡中不同种类的碳水化合物的积累似乎有助于细胞的扩张，从而导致花的开放。

During flower opening, large amount of soluble carbohydrates accumulates, suggesting that soluble carbohydrates play important roles as osmotica in plant cells. In the present study, carbohydrate concentration in cytoplasm, vacuole and apoplast in rose petals was determined and compared with total osmotic potential and osmotic potential derived from carbohydrates. A method for the evaluation of subcellular carbohydrate distributions in petals was developed by combining nonaqueous fractionation method and infiltration-centrifuged method. The volumes of subcellular compartments of petal cells were determined using electron microscope observations. Glucose and fructose concentrations in cytoplasm, vacuole and apoplast were drastically increased with petal opening. With petal opening, total osmotic potentials in symplastic and apoplastic solutions increased. In comparing total osmotic potential with osmotic potential derived from carbohydrates, increase in total osmotic potential with petal opening was mainly attributed to increase in osmotic potential derived from carbohydrates. Thus, accumulation of carbohydrates in the vacuole appears to contribute to cell expansion, leading to the petal opening. To clarify whether carbohydrates accumulate in the vacuole, carbohydrate distributions in cytoplasm, vacuole and apoplast of snapdragon, delphinium, Eustoma grandiflorum, Phlox drummondii, Gentiana triflora var.japonica flowers were investigated. Glucose and fructose in snapdragon, glucose, fructose and mannitol in delphinium, sucrose and glucose in E.grandiflorum, glucose and 2-C-methyl erythritol in P.durmmondii, gentiobiose and sucrose in G.triflora var.japonica increased with petal opening. These carbohydrates distributed mostly in vacuole. In these flowers, accumulation of different carbohydrates depended on species in the vacuole appears to contribute to cell expansion, leading to the flower opening.