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营养作用。本研究测定了玫瑰花瓣细胞质、液泡和质外体中的碳水化合物浓度，并与总渗透势和碳水化合物渗透势进行了比较。将非水分级分离法与渗透离心法相结合，建立了一种测定花瓣亚细胞碳水化合物分布的方法。用电子显微镜观察花瓣细胞的亚细胞室的体积。细胞质、液泡和质外体中的葡萄糖和果糖含量随着花瓣的开放而显著增加。随着花瓣开放，共质体和质外体溶液中的总渗透势增加。在比较总渗透势与来自碳水化合物的渗透势时，总渗透势随花瓣打开的增加主要归因于来自碳水化合物的渗透势的增加。因此，碳水化合物在液泡中的积累似乎有助于细胞扩张，导致花瓣开放。为了明确糖是否在液泡中积累，对金鱼草、飞燕草、洋桔梗、福禄考、龙胆花的细胞质、液泡和质外体中糖的分布进行了研究。金鱼草中葡萄糖和果糖、翠雀花中葡萄糖、果糖和甘露醇、桔梗中蔗糖和葡萄糖、杜蒙地桔梗中葡萄糖和2-C-甲基异麦芽糖、三花龙胆中龙胆二糖和蔗糖均随花瓣开放而增加。这些碳水化合物主要分布在液泡中。在这些花中，不同种类的碳水化合物在液泡中的积累似乎有助于细胞扩张，导致花开放。

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.