Determination of subcellular concentrations of soluble carbohydrates in rose petals during opening by nonaqueous fractionation method combined with infiltration–centrifugation method

Abstract

Petal growth associated with flower opening depends on cell expansion. To understand the role of soluble carbohydrates in petal cell expansion during flower opening, changes in soluble carbohydrate concentrations in vacuole, cytoplasm and apoplast of petal cells during flower opening in rose (Rosa hybrida L.) were investigated. We determined the subcellular distribution of soluble carbohydrates by combining nonaqueous fractionation method and infiltration-centrifugation method. During petal growth, fructose and glucose rapidly accumulated in the vacuole, reaching a maximum when petals almost reflected. Transmission electron microscopy showed that the volume of vacuole and air space drastically increased with petal growth. Carbohydrate concentration was calculated for each compartment of the petal cells and in petals that almost reflected, glucose and fructose concentrations increased to higher than 100 mM in the vacuole. Osmotic pressure increased in apoplast and symplast during flower opening, and this increase was mainly attributed to increases in fructose and glucose concentrations. No large difference in osmotic pressure due to soluble carbohydrates was observed between the apoplast and symplast before flower opening, but total osmotic pressure was much higher in the symplast than in the apoplast, a difference that was partially attributed to inorganic ions. An increase in osmotic pressure due to the continued accumulation of glucose and fructose in the symplast may facilitate water influx into cells, contributing to cell expansion associated with flower opening under conditions where osmotic pressure is higher in the symplast than in the apoplast.

Cell Division and Expansion in Petals during Flower Development and Opening in <i>Eustoma grandiflorum</i>

“…Soluble carbohydrate concentrations in the petals increase during flower opening in many flowers, including carnation , rose (Yamada et al, 2009a), and T. caerulea (Norikoshi et al, 2013), suggesting that soluble carbohydrates act as osmotica. In rose petal cells, soluble carbohydrates accumulate in vacuoles, resulting in decreased osmotic potential, which is associated with cell expansion during flower (Yamada et al, 2009a). Expansion of petal cells during flower opening in rose is associated with enlargement of vacuoles and disappearance of plastids (Yamada et al, 2009a, b).…”

2-Cyanoethyl-isoxazolin-5-one Is a Major Low Molecular Weight Nitrogenous Compound in Sweet Pea (<i>Lathyrus odoratus</i> L.)

“…synthetic materials as well as osmotica (Yamada et al, 2009). The 2-CEIX content in the petals was high, particularly at stage 1 (Fig.…”

“…Thus, 2-CEIX appears to be less important than monosaccharides and sucrose for flower opening. In rose flowers, fructose and glucose mainly accumulate in the vacuole in rose petals, and contribute to petal cell expansion associated during flower opening (Yamada et al, 2009). Subcellular contents of 2-CEIX in sweet pea petals should be investigated to clarify its function for cell expansion.…”

Leaves Of Cut Rose Flower Convert Exogenously Applied Glucose To Sucrose And Translocate It To Petals

“…Soluble carbohydrate contents were also kept high in petals of cut flowers with leaves, while those without leaves were low even when treated with 1% glucose. Soluble carbohydrates accumulation in petal cells leads to the reduction of petal water potential and promotes water influx for cell expansion (Ichimura et al 2003;Yamada et al 2009). Thus, it seems that the translocation of soluble carbohydrates from leaves to petals is important for flower development of cut flower.…”

“…We consider that radioactive glucose accumulated in the cytosol in leaf cells was used for synthesis of sucrose there, and the synthesised sucrose was transported to petals whereas the rest of it was stored in vacuoles. In vacuoles, large amounts of soluble carbohydrates containing sucrose are stored, so that the specific activity of sucrose is weakened by dilution (Yamada et al 2009). Meanwhile in petals, the amount of accumulated sucrose is lower than that in leaves, so that translocated sucrose would not be diluted much.…”