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Changes in Cell Number, Osmotic Potential and Concentrations of Carbohydrates and Inorganic Ions in Tweedia caerulea during Flower Opening
Abstract
The number of epidermal cells, osmotic potential, and carbohydrate and inorganic ion concentrations in petals during development and opening of Tweedia caerulea D. Don flowers was studied. The number of adaxial epidermal cells was greater than that of abaxial epidermal cells at all stages. The increase in cell number stopped at the stage just before flower opening. The size of adaxial and abaxial epidermal cells increased during flower development and opening. The results indicate that petal growth before flower opening depended on cell division and expansion, and petal growth during flower opening was attributable to petal cell expansion. Osmotic potential decreased and fructose, glucose and sucrose concentrations in the petals gradually increased during flower opening. Starch content and total inorganic ion concentration were almost constant during flower opening. Decreased osmotic potential is mainly attributed to increased glucose, fructose and sucrose concentrations. It is concluded that an increase in these sugar concentrations largely contributes to the decrease in osmotic potential. This decrease may facilitate water influx to cells, thereby maintaining pressure potential, which is apparently involved in petal cell expansion associated with flower opening.
... In Gaillardia grandiflora (Koning, 1984), cell division in petals ceased at an early stage of flower opening. Similarly, petal growth during flower opening has been shown to occur mainly as a result of cell expansion in rose (Yamada et al., 2009b), Tweedia caerulea (Norikoshi et al., 2013), and Eustoma grandiflorum (Norikoshi et al., 2016). These findings indicate that the petal growth associated with flower opening depends on cell expansion. ...
... Petal limb pieces (0.2 g FW) were frozen in liquid nitrogen, placed in a centrifugal filter device (Merk Millipore), and centrifuged at 12,000 × g for 10 min. The resulting fluids were used to determine inorganic ion concentrations by HPLC, as previously described by Norikoshi et al. (2013). ...
... These results indicate that the petal growth associated with flower opening in P. drummondii is due to cell expansion. Similar findings have been reported in rose (Yamada et al., 2009b), E. grandiflorum (Norikoshi et al., 2016), G. grandiflora (Koning, 1984), and T. caerulea (Norikoshi et al., 2013). ...
Flower opening is associated with the expansion of petal cells. To understand the role played by soluble carbohydrates during cell expansion associated with petal growth, changes in soluble carbohydrate concentrations in petal limbs during flower opening in Phlox drummondii were investigated. The size of adaxial and abaxial epidermal cells in the petal limbs gradually increased during flower opening. 2-C-Methyl-d-erythritol (2-C-ME) was identified using ¹H-NMR in P. drummondii petals. 2-C-ME was the most abundant carbohydrate in the petal limbs at five developmental stages, with the concentration of glucose the second highest, although the concentration of the latter was half of that of the 2-C-ME concentration in all five stages. The concentrations of 2-C-ME and glucose increased during flower opening. In contrast, inorganic ion concentrations did not increase during flower opening. The osmotic potential of petal limbs decreased considerably during the final stage of flower opening; this decrease could in part be attributed to the increasing 2-C-ME concentration. Transmission electron microscopic observations showed that the petal limb cells in open flowers were occupied primarily by the vacuole. The concentration of 2-C-ME in the vacuole was estimated to be 131 mM, which was much higher than the concentrations of the other carbohydrates. We conclude that the accumulation of 2-C-ME in the vacuole at a high concentration acts as an osmoticum, decreasing the osmotic potential of petal limbs and thereby increasing turgor pressure, which is thought to be involved in cell expansion of petal limbs during flower opening.
... Flower opening involves petal growth, which mainly results from the expansion of petal cells (Kenis et al., 1985;Koning, 1984;Norikoshi et al., 2013). Previous studies demonstrated sugar accumulation (Evans and Reid, 1988;Ho and Nichols, 1977;Norikoshi et al., 2013;Yamada et al., 2009) and a decrease in osmotic potential in petals during flower opening (Norikoshi et al., 2013;Yamada et al., 2009), which is thought to contribute to cell expansion by promoting water influx into the petal cells. ...
... Flower opening involves petal growth, which mainly results from the expansion of petal cells (Kenis et al., 1985;Koning, 1984;Norikoshi et al., 2013). Previous studies demonstrated sugar accumulation (Evans and Reid, 1988;Ho and Nichols, 1977;Norikoshi et al., 2013;Yamada et al., 2009) and a decrease in osmotic potential in petals during flower opening (Norikoshi et al., 2013;Yamada et al., 2009), which is thought to contribute to cell expansion by promoting water influx into the petal cells. Influx of water into cells is mediated by channel protein aquaporins (AQPs) (Maurel et al., 2008). ...
... Flower opening involves petal growth, which mainly results from the expansion of petal cells (Kenis et al., 1985;Koning, 1984;Norikoshi et al., 2013). Previous studies demonstrated sugar accumulation (Evans and Reid, 1988;Ho and Nichols, 1977;Norikoshi et al., 2013;Yamada et al., 2009) and a decrease in osmotic potential in petals during flower opening (Norikoshi et al., 2013;Yamada et al., 2009), which is thought to contribute to cell expansion by promoting water influx into the petal cells. Influx of water into cells is mediated by channel protein aquaporins (AQPs) (Maurel et al., 2008). ...
Transport of water into cells is mediated by plasma membrane intrinsic protein (PIP) families of aquaporin, which are involved in petal cell expansion during flower opening. In this study, we performed comprehensive characterization of aquaporin family genes and analyzed the expression of PIP genes in petals of opening flowers to examine the role of PIPs in flower opening in the carnation (Dianthus caryophyllus L.). A database search of the genome sequence revealed the existence of 26 aquaporin genes with 8 members of the PIP subfamily in the carnation ‘Francesco’. The expression of all the PIP genes was validated by the existence of expressed sequence tags, and expression analysis by quantitative reverse transcription-PCR showed that DcPIP2;1 and DcPIP1;1 are the two major PIP isoforms expressed in petals of the ‘Pure Red’ carnation. The transcripts of these two genes were also detected abundantly in other floral tissues including the calyx, style, receptacle, and ovary, as well as stems and leaves. The expression of DcPIP2;1 and DcPIP1;1 in petals was maintained at a high level throughout the flower opening process. These data suggest a putative role of these PIPs in petal growth for flower opening.
... Cut Eustoma inflorescence has many flowers with different shown to stop at an early stage of flower development. Similarly, flower opening in the rose (Yamada et al., 2009b) and Tweedia caerulea (Norikoshi et al., 2013) is mainly due to cell expansion. Also, the final stage of petal growth associated with flower opening is due to cell expansion in Eustoma (Norikoshi et al., 2016). ...
... In many flowers, including the daylily (Bieleski, 1993), rose (Evans and Reid, 1988), and T. caerulea (Norikoshi et al., 2013), the FW/DW ratio increases during flower opening. However, in our study, petal FW and DW increased during flower opening, but the FW/DW ratio decreased between stages 4 and 5 (Fig. 1). ...
... As reported in many plants, including the rose (Yamada et al., 2009a) and T. caurulea (Norikoshi et al., 2013) petals, K + was a major cation as an osmoticum in the symplast and apoplast (Fig. 4). Moreover, Cl − levels were much higher in Eustoma petals than in the rose and T. caurulea petals (Norikoshi et al., 2013;Yamada et al., 2009a). ...
Petal growth associated with flower opening is due to cell expansion. To elucidate the role of soluble carbohydrates in expansion of petal cells in Eustoma grandiflorum, its soluble carbohydrates were identified, and changes in their subcellular concentrations during flower opening were investigated. In addition to glucose, fructose, sucrose, and myo-inositol, d-bornesitol was identified using 1H-NMR. d-Bornesitol was the major soluble carbohydrate in leaves and stems. Given that cyclitols are known to be the translocated carbohydrates in alfalfa, phloem exudate was analyzed. However, the translocated carbohydrate was suggested to be sucrose, and not d-bornesitol. In the petals, glucose and sucrose content increased whereas d-bornesitol and myo-inositol contents were almost constant during flower opening. The fructose content in petals was very low. Glucose, sucrose, myo-inositol, and d-bornesitol were found mainly in the vacuole, although sucrose was also found in the cytoplasm. In the petals of open flowers, glucose and sucrose concentrations in the vacuole increased to 60 and 53 mM. Inorganic ion concentrations in the symplast and apoplast did not increase during flower opening. The osmotic potential of the symplast and apoplast in the petals was lower at the open stage than the potential of those at the bud stage, and this difference was mainly attributed to increases in glucose and sucrose concentrations. The results suggest that the accumulation of glucose and sucrose in the vacuole reduces the symplastic osmotic potential, which appears to be involved in the cell expansion associated with flower opening, but that the contribution of d-bornesitol as an osmoticum to cell expansion is limited in Eustoma.
... In carna-tion flowers, increase in DNA content terminated when petals emerged from the calyx, suggesting that cell division stops at this stage (Kenis et al., 1985). In Gaillardia grandiflora (Koning, 1984) and Tweedia caerulea (Norikoshi et al., 2013), the division of petal cells stopped before flower opening and petal growth associated with flower opening was due to cell expansion. However, cell division in rose did not stop in open flowers, and petal growth during flower opening was due mainly to cell expansion (Yamada et al., 2009b). ...
... For petal cell expansion, accumulation of osmotica in the cells is required. 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 opening (Yamada et al., 2009a). ...
... In Eustoma flowers, petal FW and DW exponentially increased during flower opening and FW/DW ratio did not increase between stages 8 and 9 when flowers opened (Fig. 2). In other flowers including daylily (Bieleski, 1993), rose (Evans and Reid, 1988), and T. caerulea (Norikoshi et al., 2013), the FW/DW ratio increases during flower opening, suggesting that petal growth involves water influx in these plants. No decrease in the FW/DW ratio in petals during flower opening has been reported for other flowers. ...
We investigated morphological changes in petal cells during flower development and opening in Eustoma grandiflorum. The morphology of petal epidermal cells was observed by scanning electron microscopy, and their number was determined. The numbers of adaxial and abaxial epidermal cells increased during flower development. Increase in these numbers terminated before flower opening earlier in abaxial than in adaxial epidermal cells. Measurements of cell number and area showed that the petal growing stage during flower development and opening can be divided into four phases: cell division and expansion, cell division, cell division and expansion, and cell expansion. Adaxial epidermal cells in the petal blade showed a conical-papillate shape whereas adaxial epidermal cells in the petal claw were longitudinally elongated in shape. Abaxial epidermal cells were longitudinally elongated in both petal blade and claw. The ultrastructure of petal cells at the bud stage and the open stage was observed by transmission electron microscopy. In the petal cells at the bud stage, nuclei and several plastids were observed, although the cells were mainly occupied with vacuoles. Relatively large spherical electron-dense bodies were observed only in the vacuoles of adaxial epidermal cells at the bud stage. The petal cells were largely occupied with enlarged vacuoles at the open stage. We conclude that petal growth in Eustoma is divided into four phases, based on the activities of cell division and expansion, and that petal growth in the final phase is mainly due to cell expansion with marked enlargement of vacuoles.
... In several species, anthesis coincides with rapid changes in petal fresh mass and osmotic potential, which correlate with dynamic reconfigurations of carbohydrate composition (Yap et al., 2008;Norikoshi et al., 2013). We quantified changes in limb fresh mass at the beginning and at the completion of anthesis (3 and 7:30 PM; Figure 8B). ...
... Dynamic changes in carbohydrate metabolism during flower opening have been reported repeatedly in different plants (Evans and Reid, 1988;Ichimura et al., 2000;Yap et al., 2008;Norikoshi et al., 2013). In light of the pronounced developmental effects seen after COR treatments, we conducted a microarray experiment to identify genes coding for biological processes differentially regulated after COR treatment of ir-aoc flowers (Supplemental Figures 12 and 13). ...
... Monitoring floral opening during the first night of anthesis revealed no apparent time shift for full or partial limb expansion among the genotypes irrespective of the treatments ( Figure 8A). Anthesis is paralleled by a substantial increase in petal fresh mass, quantitatively caused by a water influx driven by a rapid increase in the cellular osmolarity of petal cells (Yap et al., 2008;Norikoshi et al., 2013). Interrupting or diverting JA biosynthesis resulted in lower limb fresh mass at the beginning and end of limb expansion ( Figure 8B). ...
Jasmonic acid and its derivatives (jasmonates [JAs]) play central roles in floral development and maturation. The binding of jasmonoyl-L-isoleucine (JA-Ile) to the F-box of CORONATINE INSENSITIVE1 (COI1) is required for many JA-dependent physiological responses, but its role in anthesis and pollinator attraction traits remains largely unexplored. Here, we used the wild tobacco Nicotiana attenuata, which develops sympetalous flowers with complex pollination biology, to examine the coordinating function of JA homeostasis in the distinct metabolic processes that underlie flower maturation, opening, and advertisement to pollinators. From combined transcriptomic, targeted metabolic, and allometric analyses of transgenic N. attenuata plants for which signaling deficiencies were complemented with methyl jasmonate, JA-Ile, and its functional homolog, coronatine (COR), we demonstrate that (1) JA-Ile/COR-based signaling regulates corolla limb opening and a JA-negative feedback loop; (2) production of floral volatiles (night emissions of benzylacetone) and nectar requires JA-Ile/COR perception through COI1; and (3) limb expansion involves JA-Ile-induced changes in limb fresh mass and carbohydrate metabolism. These findings demonstrate a master regulatory function of the JA-Ile/COI1 duet for the main function of a sympetalous corolla, that of advertising for and rewarding pollinator services. Flower opening, by contrast, requires JA-Ile signaling-dependent changes in primary metabolism, which are not compromised in the COI1-silenced RNA interference line used in this study. INTRODUCTION
... In addition, xyloglucan oligosaccharides (XGO) treatment was found to promote flower opening in some carnation cultivars including 'Pure Red' in the course of our study on chemical control of flower opening in carnations (Satoh et al., 2013). Flower opening involves petal growth, which mainly results from the expansion of petal cells (Kenis et al., 1985; Koning, 1984; Norikoshi et al., 2013). Previous studies demonstrated sugar accumulation (Evans and Reid, 1988; Ho and Nichols, 1977; Norikoshi et al., 2013; Yamada et al., 2009) and a decrease in osmotic potential in petals during flower opening (Norikoshi et al., 2013; Yamada et al., 2009), which is thought to contribute to cell expansion by promoting water influx into the petal cells. ...
... Flower opening involves petal growth, which mainly results from the expansion of petal cells (Kenis et al., 1985; Koning, 1984; Norikoshi et al., 2013). Previous studies demonstrated sugar accumulation (Evans and Reid, 1988; Ho and Nichols, 1977; Norikoshi et al., 2013; Yamada et al., 2009) and a decrease in osmotic potential in petals during flower opening (Norikoshi et al., 2013; Yamada et al., 2009), which is thought to contribute to cell expansion by promoting water influx into the petal cells. Influx of water into cells is JSHS ...
... Flower opening involves petal growth, which mainly results from the expansion of petal cells (Kenis et al., 1985; Koning, 1984; Norikoshi et al., 2013). Previous studies demonstrated sugar accumulation (Evans and Reid, 1988; Ho and Nichols, 1977; Norikoshi et al., 2013; Yamada et al., 2009) and a decrease in osmotic potential in petals during flower opening (Norikoshi et al., 2013; Yamada et al., 2009), which is thought to contribute to cell expansion by promoting water influx into the petal cells. Influx of water into cells is JSHS ...
Prolamins, a group of rice (Oryza sativa) seed storage proteins, are synthesized on the rough endoplasmic reticulum (ER) and deposited in ER-derived type I protein
bodies (PB-Is) in rice endosperm cells. The accumulation mechanism of prolamins, which do not possess the well-known ER retention
signal, remains unclear. In order to elucidate whether the accumulation of prolamin in the ER requires seed-specific factors,
the subcellular localization of the constitutively expressed green fluorescent protein fused to prolamin (prolamin–GFP) was
examined in seeds, leaves, and roots of transgenic rice plants. The prolamin–GFP fusion proteins accumulated not only in the
seeds but also in the leaves and roots. Microscopic observation of GFP fluorescence and immunocytochemical analysis revealed
that prolamin–GFP fusion proteins specifically accumulated in PB-Is in the endosperm, whereas they were deposited in the electron-dense
structures in the leaves and roots. The ER chaperone BiP was detected in the structures in the leaves and roots. The results
show that the aggregation of prolamin–GFP fusion proteins does not depend on the tissues, suggesting that the prolamin–GFP
fusion proteins accumulate in the ER by forming into aggregates. The findings bear out the importance of the assembly of prolamin
molecules and the interaction of prolamin with BiP in the formation of ER-derived PBs.
... The concentrations of these four macronutrients in the study surpassed 1 mg/g, with ranges from 1.45 to 3.08 mg/g for Na; 3.86 to 6.62 mg/g for Mg; 25.80 to 48.06 mg/g for K; and 17.27 to 31.00 mg/g for Ca (Table 5). K showed the highest content among all nutrients, matching the high K levels previously reported in Tweedia caerulea during floral development and blooming [24]. Adequate K helps lower stroke and heart disease risk, while also protecting against ...
... The concentrations of these four macronutrients in the study surpassed 1 mg/g, with ranges from 1.45 to 3.08 mg/g for Na; 3.86 to 6.62 mg/g for Mg; 25.80 to 48.06 mg/g for K; and 17.27 to 31.00 mg/g for Ca (Table 5). K showed the highest content among all nutrients, matching the high K levels previously reported in Tweedia caerulea during floral development and blooming [24]. Adequate K helps lower stroke and heart disease risk, while also protecting against bone loss and kidney stones [25]. ...
Houpoea officinalis (H. officinalis) flowers are rich in a spectrum of bioactive compounds and mineral nutrients. The availability and balance of mineral elements directly impact the morphogenesis of flower organs, which play pivotal roles in various physiological and biochemical processes that drive flower development. However, relatively little is known about the changes in mineral elements composition that occur during flower development in H. officinalis. The objective of this study is to analyze the variations of 22 mineral elements contents in pistil, stamens, and petals of H. officinalis flower at four development stages. The amount of mineral elements (Na, Mg, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Sn, Al, Ti, Ga, Cd, Ba, Tl, Pb, and Bi) in these samples was determined using atomic absorption spectroscopy and inductively coupled plasma mass spectrometry. Results showed that H. officinalis flowers are rich in macroelements such as potassium (K, 25.80–48.06 mg/g) and calcium (Ca, 17.27–31.00 mg/g), as well as microelements like zinc (Zn, 445.17–1553.16 μg/g) and iron (Fe, 324.27–622.31 μg/g). Notably, the pistil part is found to harbor a more significant concentration of mineral elements during the early developmental stages of flowers. Correlation analysis and PCA have effectively exposed a pronounced association between the accumulation patterns of mineral elements in H. officinalis flowers and their corresponding developmental stages and organs. These findings will provide more detailed information about the accumulation and distribution of mineral elements in H. officinalis flowers at different development stages and organs, which help to encourage researchers to enhance the flower quality for human consumption.
... Studies on a variety of flowering plants have shown that NSCs are essential to floral development from floral initiation to the maturation of floral organs [4,22]. In many flowers, including roses and T. caerulea, the contents of glucose and fructose in the petals increase during flower opening [23,24]. In rose petals, decreased osmotic potential is mainly attributed to increased soluble carbohydrate contents [23]. ...
... That is, RWC is the highest in the blooming stage and the lowest in the subsequent ageing and wilting of flowers [37,38]. The present results showed that the RWC of H. officinalis flowers reached its minimum value at Stage III (Table 2), which was consistent with the results of previous studies [1,17,24]. A higher RWC can lead to a greater water potential gradient, further causing cell expansion, which is the primary driving force behind flower opening [39]. ...
Mineral elements and non-structural carbohydrates (NSCs) are important nutrients and energy sources for flower development in plants. However, no studies were reported on the dynamic changes of nutrient stoichiometry and NSC contents in Houpoea officinalis (H. officinalis) flower. In this study, the changes in carbon (C), nitrogen (N), phosphorus (P), and NSC contents as well as C:N:P stoichiometry in the pistil, stamen, and petal of H. officinalis flowers at four developmental stages were comparatively analyzed. The results showed that C, N, P, and NSC contents, as well as C:N:P stoichiometric ratios in the three parts of the flower exhibited large variations at four development stages. Development stages and organs had significant effects on the measured parameters in the three organs of H. officinalis flowers, but their interactions had no significant effects. During the flower development, C, N, and P contents in different floral parts ranged from 418.7 to 496.3 mg/g, 26.6 to 45.3 mg/g, and 0.396 to 0.656 mg/g. P content decreased continuously with development, C:N in stamen were significantly higher than those in other flower parts at the same developmental stage. Glucose, starch, fructose, and sucrose contents showed significant differences in three parts of H. officinalis flowers at four development stages. These differences may reflect differences in elemental storage capacity and biomass allocation patterns of H. officinalis flowers. In general, our data will help to improve our understanding of the relationship between NSCs and C:N:P stoichiometry in response to development stages and organs in H. officinalis flowers.
... Moreover, soluble carbohydrates depending on the degradation of polysaccharides can act as osmotically active compounds which could lower the osmotic water potential and facilitate water influx in order to allow cell expansion [12]. The concentration of soluble carbohydrates in the petals will increase in the flower opening process of plants such as carnation [13], rose [14], chrysanthemum [15], Tweedia caerulea [16], and lisianthus [17]. ...
... Observation on the cell size of adaxial and abaxial petal epidermal cells with SEM revealed that cell size of adaxial petal epidermal cells increased gradually (P < 0.05, by Duncan's multiple range test) from S1 to S6 (Fig. 1a, Table S1), while that of abaxial petal epidermal cells enlarged gradually from S1 to S5, reached the peak at S5, and then greatly decreased from S5 to S6 (Fig. 1b, Table S1). These results were coincident with results in Gaillardia grandiflora [23], carnation [24] and T. caerulea [16], indicating that the cell division ceased and cell expansion occurred during floral opening process. However, in rose [25] and E. grandiflorum [26] cell division and cell expansion simultaneously appeared during this process. ...
Background:
Sweet osmanthus (Osmanthus fragrans Lour.) is one of the top ten traditional ornamental flowers in China. The flowering time of once-flowering cultivars in O. fragrans is greatly affected by the relatively low temperature, but there are few reports on its molecular mechanism to date. A hypothesis had been raised that genes related with flower opening might be up-regulated in response to relatively low temperature in O. fragrans. Thus, our work was aimed to explore the underlying molecular mechanism of flower opening regulated by relatively low temperature in O. fragrans.
Results:
The cell size of adaxial and abaxial petal epidermal cells and ultrastructural morphology of petal cells at different developmental stages were observed. The cell size of adaxial and abaxial petal epidermal cells increased gradually with the process of flower opening. Then the transcriptomic sequencing was employed to analyze the differentially expressed genes (DEGs) under different number of days' treatments with relatively low temperatures (19 °C) or 23 °C. Analysis of DEGs in Gene Ontology analysis showed that "metabolic process", "cellular process", "binding", "catalytic activity", "cell", "cell part", "membrane", "membrane part", "single-organism process", and "organelle" were highly enriched. In KEGG analysis, "metabolic pathways", "biosynthesis of secondary metabolites", "plant-pathogen interaction", "starch and sucrose metabolism", and "plant hormone signal transduction" were the top five pathways containing the greatest number of DEGs. The DEGs involved in cell wall metabolism, phytohormone signal transduction pathways, and eight kinds of transcription factors were analyzed in depth.
Conclusions:
Several unigenes involved in cell wall metabolism, phytohormone signal transduction pathway, and transcription factors with highly variable expression levels between different temperature treatments may be involved in petal cell expansion during flower opening process in response to the relatively low temperature. These results could improve our understanding of the molecular mechanism of relatively-low-temperature-regulated flower opening of O. fragrans, provide practical information for the prediction and regulation of flowering time in O. fragrans, and ultimately pave the way for genetic modification in O. fragrans.
... Soluble carbohydrates depending on the degradation of polysaccharides can act as osmotically active compounds which could lower the osmotic water potential and facilitate water influx in order to allow cell expansion [12]. The concentration of soluble carbohydrates in the petals will increase in the flower opening process such as carnation [13], rose [14], chrysanthemum [15], Tweedia caerulea [16], and lisianthus [17]. ...
... At the same time, the cell size of adaxial petal epidermal cells increased gradually from S1 to S6 (Fig. 1a), while that of abaxial petal epidermal cells enlarged gradually from S1 to S5, reached the peak at S5, and then greatly decreased from S5 to S6 (Fig. 1b). This results was coincident with Gaillardia grandiflora [29], carnation [30] and T. caerulea [16], the cell division ceased and cell expansion occurred during floral opening process. However, in rose [31] and E. grandiflorum [32] cell division and cell expansion simultaneously appeared during this process. ...
Background: Osmanthus fragrans Lour. is one of the top ten traditional ornamental flower in China. The flower time of once-flowering cultivars in O. fragrans is greatly affected by the relatively low temperature, but there is few reports on its molecular mechanism to date.
Results: In this study, the cell size of adaxial and abaxial petal epidermal cells and ultrastructural morphology of petal cells at different developmental stages were observed. The cell size of adaxial and abaxial petal epidermal cells increased gradually with the process of flower opening. Then the transcriptomic sequencing was employed to analyze the differentially expressed genes (DEGs) under different days’ treatments with relatively low temperatures (19°C) or 23°C. Analysis of DEGs in GO analysis showed that “metabolic process”, “cellular process”, “binding”, “catalytic activity”, “cell”, “cell part”, “membrane”, “membrane part”, “single-organism process”, and “organelle” were highly enriched. In KEGG analysis, “metabolic pathways”, “biosynthesis of secondary metabolites”, “plant-pathogen interaction”, “starch and sucrose metabolism”, and “plant hormone signal transduction” were the top five pathways containing the greatest number of DEGs. DEGs involved in cell wall metabolism, phytohormone signal transduction pathways, and eight kinds of transcription factors were analyzed in depth.
Conclusions: Several unigenes involved in cell wall metabolism, phytohormone signal transduction pathway, and TFs with highly variable expression levels between different temperature treatments may be involved in petal cell expansion during flower opening process in response to the relatively low temperature. These results could improve our understanding of the molecular mechanism of relatively low temperature regulating flower opening of O. fragrans and provide theoretical reference for the prediction and regulation of flowering time and genetic modification in O. fragrans.
... Torch ginger belongs to the genus Etlingera and, due to its exotic characteristics and beauty, has become one of the tropical ornamental plants with the greatest commercialization potential, although the information about this tropical plant is still restricted (LOGES et al., 2008). Its commercialization is based on different harvest stages, starting from "closed" (stage in which the basal bracts begin to expand) to the full expansion (RIBEIRO et al., 2012;MATTOS et al., 2017). ...
... Therefore, for floral opening, the cells need to expand, requiring energy (VAN DOORN and VAN MEETEREN, 2003, COSTA andFINGER, 2016;SALES et al., 2018) and water absorption; thus, this phenomenon is dependent on reserve mobilization, as demonstrated in Tweedia caerulea flowers, in which an increase in sugars concentrations induces decrease on osmotic potential. This contribut to water influx that will maintain the pressure potential, an aspect that is maybe involved in cell expansion and floral opening (ICHIMURA et al., 2013). ...
Floral opening stage during harvest and use of postharvest techniques, such as inflorescence coating with carnauba wax, may influence quality maintenance for commercialization. The aim was to evaluate the carbohydrate content of torch ginger inflorescences harvested at two different opening stages and treated with different concentrations of carnauba wax. The inflorescences were harvested with semi-open (basal bracts beginning their expansion process) and open bracts (fully expanded basal bracts and opening of the smaller bracts on interior of the inflorescence) and received the application of carnauba wax at concentrations of 0.75%; 1.5% or 3.0%, in addition to a control treatment, without wax application. After the treatment, the floral stems were maintained at 16 and 21 oC for 20 days. During the storage period, five bracts samples (external and internal bracts separately - in open inflorescences, external and internal bracts together - in semi-open inflorescences) were carried out every three days for evaluation of total soluble sugars and starch content. Contents of total soluble sugars and starch differed between the different types of bracts collected and throughout the storage period evaluated, and could indicate a remobilization of reserves. The concentration of 3.0% carnauba wax
induced higher total soluble sugar content. However, this content does not affect the longevity of torch ginger at the two evaluated floral opening stages.
... Pressure potential was calculated by subtracting the recorded values for osmotic potential from the water potential. The osmotic potential measured was the total osmotic potential of petal tissue that was derived from not only soluble NSCs, but also other components such as soluble proteins, amino acids, organic and inorganic compounds (Nilsen and Orcutt, 1996;Norikoshi et al., 2013). To evaluate the contribution of soluble carbohydrates to the total osmotic potential of petal tissue, according to the molality of soluble TNC measured above, the osmotic potential derived from soluble TNC was calculated using the van 't Hoff factor, as described by (Gonzalez and Reigosa Roger, 2001). ...
... It has been suggested that the rapid hydrolysis of starch and/or fructan in petals during the opening of flowers of other species results in increases of fructose and/or glucose, which contribute to the osmotic driving force involved in water uptake, cell expansion and flower opening (Kumar et al., 2008;Norikoshi et al., 2013). The results of the current study illustrate substantial accumulation of soluble gentianose in petals during bud development before opening (accounting for approximately 50% of TNC at Stage 4), which was rapidly hydrolysed during floret opening to reach near zero at full opening (Stage 6). ...
During the development and senescence of florets in gentian ‘Showtime Spotlight’, there was a dramatic change in petal non-structural carbohydrates (NSCs), including accumulation, and hydrolysis. Gentianose concentration increased more than ten-fold with the development of florets, to a maximum of 26.1 mg g⁻¹ fresh weight (FW) just before floret opening. Subsequently, as florets began opening, the gentianose concentration sharply decreased to almost nothing as flowers progressed from fully open to naturally senesced. Gentiobiose concentration increased gradually during early development of florets, with the pattern of increase with each stage of development being slightly behind that for gentianose, reaching a maximum of 21.2 mg g⁻¹ FW as florets began opening. These stage-specific changes in concentrations in each NSC were paralleled by significant changes in activity of both gentianose and gentiobiose glycoside hydrolase. In a plant system devoid of starch, and where changes in sucrose and glucose concentration were comparatively small, the stage-specific and intensive fluctuation of the unique carbohydrates gentianose and gentiobiose imply an important role in controlling gentian floret development and opening. The significant positive correlation between the osmolality of soluble NSCs and pressure potential supports the hypothesis that this carbohydrate metabolism role is via osmotically driven cell expansion.
... The flower opening defect in jar1b is mainly due to a loss of maturation of the adaxial side of the corolla, which delays and reduces the growth rate and elongation of the petals. In Dendrobium and Tweedia caerulea, the opening of the flower is parallel to a significant increase in the fresh mass of the petals, caused by an influx of water (Yap et al., 2008;Norikoshi et al., 2013). Furthermore, the transcriptomic analysis of JA-deficient plants proposed that JA substantially regulates carbohydrate metabolism during flower maturation in tobacco (Stitz et al., 2014). ...
... Observation on the cell size of adaxial and abaxial petal epidermal cells with SEM revealed that cell size of adaxial petal epidermal cells increased gradually (P <0.05, by Duncan's multiple range test) from S1 to S6 (Fig. 1a, Table S1), while that of abaxial petal epidermal cells enlarged gradually from S1 to S5, reached the peak at S5, and then greatly decreased from S5 to S6 (Fig. 1b, Table S1). These results were coincident with results in Gaillardia grandi ora [23], carnation [24] and T. caerulea [16], indicating that the cell division ceased and cell expansion occurred during oral opening process. However, in rose [25] and E. grandi orum [26] cell division and cell expansion simultaneously appeared during this process. ...
Background: Sweet osmanthus ( Osmanthus fragrans Lour.) is one of the top ten traditional ornamental flowers in China. The flowering time of once-flowering cultivars in O . fragrans is greatly affected by the relatively low temperature, but there are few reports on its molecular mechanism to date. A hypothesis had been raised that genes related with flower opening might be up-regulated in response to relatively low temperature in O . fragrans . Thus, our work was aimed to explore the underlying molecular mechanism of flower opening regulated by relatively low temperature in O . fragrans .
Results: The cell size of adaxial and abaxial petal epidermal cells and ultrastructural morphology of petal cells at different developmental stages were observed. The cell size of adaxial and abaxial petal epidermal cells increased gradually with the process of flower opening. Then the transcriptomic sequencing was employed to analyze the differentially expressed genes (DEGs) under different number of days’ treatments with relatively low temperatures (19°C) or 23°C. Analysis of DEGs in Gene Ontology analysis showed that “metabolic process”, “cellular process”, “binding”, “catalytic activity”, “cell”, “cell part”, “membrane”, “membrane part”, “single-organism process”, and “organelle” were highly enriched. In KEGG analysis, “metabolic pathways”, “biosynthesis of secondary metabolites”, “plant-pathogen interaction”, “starch and sucrose metabolism”, and “plant hormone signal transduction” were the top five pathways containing the greatest number of DEGs. The DEGs involved in cell wall metabolism, phytohormone signal transduction pathways, and eight kinds of transcription factors were analyzed in depth.
Conclusions: Several unigenes involved in cell wall metabolism, phytohormone signal transduction pathway, and transcription factors with highly variable expression levels between different temperature treatments may be involved in petal cell expansion during flower opening process in response to the relatively low temperature. These results could improve our understanding of the molecular mechanism of relatively-low-temperature-regulated flower opening of O. fragrans , provide practical information for the prediction and regulation of flowering time in O . fragrans , and ultimately pave the way for genetic modification in O . fragrans .
... Cell expansion requires an increase in the osmotic pressure of vacuoles and cell extension (Yamada et al., 2009a). For cell expansion, the accumulation of osmotica and influx of water are required (Norikoshi et al., 2013). Hence, it is also essential to analyze the differences of tissue water pressures between the inner and outer sides of the bending internodes. ...
The physiological function of bamboo shoot sheaths is still unclear. In the present study, we investigated the anatomical and physiological influences of bamboo shoot sheaths on internode elongation by longitudinally striping parts of sheaths. The internodes would bend toward the bare sides during night. The results showed that amounts of water leaked at the cut of shoot sheaths during night, which impeded the increase of water, water pressure and assimilate transport rates, and decreased starch and soluble sugar catabolism in the bare side of the internodes. A higher level of water pressure and sugar metabolism increased the vacuole expansion and promoted the cell expansion in the outer sides as compared to the bare sides. The bending growth of internodes was mainly due to the significant differences in cell expansion, which was led by the difference in water pressure and sugar hydrolysis levels between the inner and outer sides. Bamboo internode elongation mainly relied on the increase of water pressure and soluble sugar concentration. Shoot sheaths played an important role in the rapid growth of bamboo shoots as a controller in water and assimilate transportation. This study gave a new insight into understanding the rapid growth mechanism of bamboo plants.
... In cut flowers, continued water uptake contributes to flower opening (Norikoshi et al., 2013). This process is mainly driven by the passive movement of water within cells, which is mediated by channel protein aquaporins (AQPs) (Beauzamy et al., 2014;Maurel et al., 2008). ...
Proper storage prolongs peony market supply. Here, we determined the changes in fresh weight and expression of four aquaporin genes under dry storage (DS) and wet storage (WS). It has showed that after harvesting, the fresh weight change was accompanied with flower opening. After both short- and long-term of storage, the water uptake efficiency in DS group was greater during the first few vase days, providing a direct material basis of DS improved vase quality. The gene expression results showed that PlPIP1;3 and PlTIP2;1 were mainly expressed in petals, whereas PlNIP1;2-like and PlSIP2;1 were mainly expressed in the green tissues. In addition, the expression of PlTIP2;1 in the petals was consistent with the flower opening process, indicating that it may play a major role in facilitating water uptake. During cold storage, the expression of PlPIP1;3 and PlTIP2;1 was higher or more rapidly induced in the DS group, and thus we deduced that they play important roles in improving the vase quality of DS. Furthermore, the expression of PlNIP1;2-like in the early stage of the DS group was more stable than in WS, which may also be partially responsible for the vase quality improvement. In contrast, PlSIP2;1 may not be involved, since no significant change was observed between the DS and WS group. In short, the expression of PlPIP1;3 and PlTIP2;1 in the DS group during storage may improve water uptake efficiency during the vase period and then improving the vase quality of cut peony.
... Petal cell expansion often correlates with the mobilization of storage carbohydrates or the accumulation of sucrose in the cells. In many angiosperms, soluble carbohydrate concentrations increase during flower opening, as shown in Dianthus caryophyllus (Ichimura et al., 1998), Rosa hybrida , and Tweedia caerulea (Norikoshi et al., 2013). Moreover, sugar accumulation in petal cells reduces the petal water potential and promotes water influx into the petal cells, resulting in a relaxation of the cell wall strength, cell enlargement, and flower opening (Ho and Nichols, 1977;Evans and Reid, 1988;Ichimura et al., 2003). ...
... However, continuing high soluble sugar contents (Fig. 8b) closely paralleled the osmolality changes in lodicules. Previous reports implied that soluble sugar concentration were involved in petal opening (Evans and Reid 1988;Bieleski 1993;Kuiper et al. 1995;Yap et al. 2008;Norikoshi et al. 2013). Moreover, it was reported that JA Scale bars 1 mm in c, d; 100 μm in e, f. ...
Key message:
OG1 is involved in JA-regulated anthesis by modulating carbohydrate transport of lodicules in rice. Flowering plants have evolved a sophisticated regulatory network to coordinate anthesis and maximize reproductive success. In addition to various environmental conditions, the plant hormone jasmonic acid and its derivatives (JAs) are involved in anthesis. However, the underlying mechanism remains largely unexplored. Here, we report a JA-defective mutant in rice (Oryza sativa), namely open glume 1, which has dysfunctional lodicules that lead to open glumes following anthesis. Map-based cloning and subsequent complementation tests confirmed that OG1 encodes a peroxisome-localized 12-oxo-phytodienoic acid reductase-a key enzyme that reduces the precursor of JA. Loss-of-function of OG1 resulted in almost no JA accumulation. Exogenous JA treatment completely rescued the defects caused by the og1 mutation. Further studies revealed that intracellular metabolism was disrupted in the lodicules of og1 mutant. At the mature plant stage, most seeds of the mutant were malformed with significantly reduced starch content. We speculate that JA or JA signaling mediates the carbohydrate transport of lodicules during anthesis, and signal the onset of cell degradation in lodicules after anthesis. We conclude that the OPEN GLUME 1 gene that produces a key enzyme involved in reducing the precursor of JA in JA biosynthesis and is involved in carbohydrate transport underlying normal lodicule function during anthesis in rice.
... These results indicate that carbohydrate metabolism may play a key role in the unclosing of rice glumes under high temperature in RGD-7S. Several recent studies also reported that carbohydrate metabolism played an important role in the coordination of developmental transitions and flower opening (Cho et al., 2006;Norikoshi et al., 2013;Wahl et al., 2013;Yang et al., 2013;Stitz et al., 2014). ...
Glume-unclosing after anthesis is a widespread phenomenon in hybrid rice and also a maternal hereditary trait. The character of Glume-unclosing in rice male sterile lines also seriously influences germination rate and the commercial quality of hybrid rice seeds. We validated that the type of glume-unclosing after anthesis in the elite rice thermo-sensitive genic male sterile (TGMS) line RGD-7S was caused by high temperature. Transcriptomic sequencing of rice panicles was performed to explore the change of transcript profiles under four conditions: pre- and post-anthesis under high temperature (HRGD0 and HRGD1), and pre- and post-anthesis under low temperature (LRGD0 and LRGD1). We identified a total of 14,540 differentially expressed genes (DEGs) including some heat shock factors (HSFs) across the four samples. We found that more genes were up-regulated than down-regulated in the sample pair HRGD1vsHRGD0. These up-regulated genes were significantly enriched in the three biological processes of carbohydrate metabolism, response to water and cell wall macromolecular metabolism. Simultaneously, we also found that the HSF gene OsHsfB1 was specially up-regulated in HRGD1vsHRGD0. However, the down-regulated DEGs in LRGD1vsLRGD0 were remarkably clustered in the biological process of carbohydrate metabolism. This suggests that carbohydrate metabolism may play a key role in regulation of glume-unclosing under high temperature in RGD-7S. We also analyzed the expression pattern of genes enriched in carbohydrate metabolism and several HSF genes under different conditions and provide new insights into the cause of rice glume-unclosing.
Drought stress is the main limiting plant growth factor in arid and semiarid regions. The Lanzhou lily (Lilium davidii var. unicolor) is the only sweet-tasting lily grown in these regions of China that offers highly edible, medicinal, health, and ornamental value. The Tresor lily is an ornamental flower known for its strong resistance. Plants were grown under three different drought intensity treatments, namely, being watered at intervals of 5, 15, and 25 d (either throughout the study or during specific growth stages). We measured the biomass, leaf area, photosynthetic response, chlorophyll content (SPAD value), and osmoregulation of both the Lanzhou lily and the Tresor lily (Lilium 'Tresor'). Additionally, we employed RNA sequencing (RNA-Seq) and qRT-PCR to investigate transcriptomic changes of the Lanzhou lily in response to drought stress. Results showed that under drought stress, the decreasing rate in the Lanzhou lily bulb weight was lower than the corresponding Tresor lily bulb rate; the net photosynthetic rate, transpiration rate, and stomatal conductance of the Lanzhou lily were all higher compared to the Tresor lily; osmoregulation constituents, such as glucose, fructose, sucrose, trehalose, and soluble sugar, in the Lanzhou lily were comparatively higher; PYL, NCED, and ERS genes were significantly expressed in the Lanzhou lily. Under moderate drought, the biosynthesis of flavonoids, circadian rhythms, and the tryptophan metabolism pathway of the Lanzhou lily were all significant. Under severe drought stress, fatty acid elongation, photosynthetic antenna protein, plant hormone signal transduction, flavone and flavonol biosynthesis, and the carotenoid biosynthesis pathway were all significant. The Lanzhou lily adapted to drought stress by coordinating its organs and the unique role of its bulb, regulating photosynthesis, increasing osmolyte content, activating circadian rhythms, signal transduction, fatty acid elongation metabolism, and phenylalanine and flavonoid metabolic pathways, which may collectively be the main adaptation strategy and mechanisms used by the Lanzhou lily under drought stress.
To understand the biochemical mechanism underlying flower opening, the mechanism of cell expansion, soluble carbohydrate concentration, and expression of expansin and xyloglucan endotransglucosylase/hydrolase (XTH) genes were investigated in the petals of Oriental lily (Lilium ‘Sorbonne’). Microscopic observation revealed that petal growth during flower opening mainly depended on cell expansion, which was accompanied by increases in glucose and fructose concentrations in the petals. The adaxial and abaxial sides of the petals grew at different rates during flower opening with petal reflection. To determine the concentration of soluble carbohydrates and the expression of expansin and XTH genes in adaxial and abaxial epidermal cells and parenchyma cells, these cells were separated using tweezers. We confirmed that these cells could be sufficiently separated. Glucose and fructose concentrations were higher in adaxial epidermal cells than in abaxial epidermal cells at the stage immediately preceding flower opening, but these differences diminished during flower opening. Three expansin genes, LhEXPA1, LhEXPA2, and LhEXPA3, and two XTH genes, LhXTH1 and LhXTH2 were isolated. LhXTH1 transcript levels in the petals markedly increased during flower opening and were higher in adaxial epidermal cells than in other types of cells. Conversely, the levels of the three EXPA transcripts decreased during flower opening and there were slight differences in their levels among different cell types, with a few exceptions. In conclusion, differences in glucose and fructose concentrations between adaxial and abaxial epidermal cells, together with the expression of LhXTH1, may contribute to cell expansion associated with flower opening.
Treatment with sucrose promoted petal growth associated with flower opening in cut roses. We investigated the effect of sucrose treatment on cell size and subcellular concentration of soluble carbohydrates in petals of cut rose cv. Sonia flowers. Petals of sucrose-treated flowers, but not control flowers, markedly curved outward, resulting in complete reflection. Petal fresh weight (FW), petal area, and adaxial epidermal cell size in the control flowers increased with time, and treatment with sucrose accelerated this increase, indicating that sucrose promotes petal cell expansion. Glucose, fructose, sucrose, methyl glucoside, and xylose were detected in the petals. In the petals of control flowers, concentration of these carbohydrates, except fructose, decreased. Sucrose treatment markedly increased glucose and fructose concentrations in petals. Estimation of subcellular volumes based on transmission electron micrographs showed that volume of cell walls and vacuoles in the petals of control flowers increased in response to sucrose treatment. Sucrose treatment increased glucose and fructose concentrations in the vacuole and glucose, fructose, and xylose concentrations in the apoplast. We concluded that sucrose treatment increases glucose and fructose concentrations in the vacuole, which may reduce the osmotic potential of the symplast and increase water uptake leading to cell expansion during flower opening.
Main conclusion:
The role of mannitol differs from that of glucose, fructose and sucrose in sepal cell expansion associated with flower opening in Delphinium × belladonna. Sepals of Delphinium × belladonna are colored and much larger than the petals. To determine whether the role of mannitol in sepal growth associated with flower opening differs from those of ubiquitous metabolic sugars including glucose, fructose and sucrose, we investigated changes in cell number, subcellular concentrations of soluble carbohydrates, and osmotic potential in sepals during flower opening in Delphinium × belladonna cv. Bellamosum. The number of epidermal cells in the sepals did not increase from the stage when sepal pigmentation started, whereas the cell area increased during flower opening, indicating that petal growth during flower opening depends on cell expansion. Mannitol concentrations in the vacuole at three different stages were approximately 100 mM, which were much higher than the other carbohydrate concentrations, but they decreased slightly at open stage. In contrast, mannitol concentration in the cytoplasm was 56 mM at bud stage, but it increased to 104 mM at open stage. Glucose and fructose concentrations in the vacuole at open stage increased to 45 and 56 mM, respectively. Total osmotic potential in apoplast and symplast, which was partially due to soluble carbohydrates, was almost constant during flower opening. Therefore, mannitol may be acting constitutively as the main osmoticum in the vacuole where it may contribute to the maintenance of the osmotic balance between the cytoplasm and vacuole in open flowers. The role of mannitol differs from those of glucose, fructose, and sucrose in sepal cell expansion in Delphinium × belladonna.
Corolla elongation and the roles of plant hormones in this process in Gaillardia grandiflora Van Houtte ray flowers were examined. The sterile ray flowers elongated during a 2-day period, and corolla growth was accompanied by fresh and dry weight increases and epidermal cell elongation (greatest near the base of the corolla) but not by cell division. Corollas excised from young ray flowers were measured during treatment in vitro with solutions of plant growth regulators. They elongated in response to gibberellins and fusicoccin but did not respond to auxins, cytokinins, abscisic acid, ethylene, or inhibitors of ethylene biosynthesis. Sequential and simultaneous hormone applications indicated no additive or synergistic effects between hormones, but auxin did reduce gibberellin-promoted growth. Analyses of endogenous auxins showed no significant variation, and ethylene production decreased prior to elongation, while a 20-fold increase in endogenous gibberellin activity was observed just prior to rapid corolla elongation. It appears that corolla growth in Gaillardia is accomplished by an increase in gibberellin activity alone, that multiple hormone interactions are not important in the control of corolla growth, and that part of the mode of action of gibberellin is acid-induced growth.
Rhythmic pulses of irreversible petal expansion in rose ( Rosa hybrida L. ‘Sonia’) petals cause diurnal changes in the rate of flower opening. Time-lapse cinematography revealed a transient increase in the rate of rose flower opening that commenced shortly before the onset of a light period and lasted for a few hours. Petal expansion, which occurred sequentially from the outer to the innermost whorl, involved rhythmic increases in fresh and dry weights. The amount of expansion was greatest in the distal portion of each petal and least near the petal base. Periods of rapid expansion were accompanied by decreases in starch and increases in soluble sugars in the petals, but the total carbohydrate content of the petals remained constant during a light–dark cycle. During expansion, the osmotic potential of the outer petal increased from −790 to −690 kPa. Starch hydrolysis during petal growth appears to be important for maintenance of cell size, but it is not the factor controlling cell expansion.
Measurement of ion concentrations in the vacuoles of different cell types in cereal leaves using a variety of techniques indicates that ions are differentially distributed between different cell types. Thus mesophyll cells are enriched in P but contain relatively little Ca2+ or Cl-, whereas the reverse is true for epidermal cells. Solutes reach the leaf via the transpiration stream and we consider three possible pathways which they could follow from the xylem to leaf cells. The first is a fully apoplastic mesophyll pathway in which both water and solutes move together through the leaf apoplast passing bundle sheath, mesophyll and epidermis in turn. The second is a partly symplastic mesophyll pathway in which ions and water pass into the symplast at the mestome/bundle sheath cells. Water continues to sites of evaporation via either a transcellular or symplastic pathway, but ions may be secreted back to the mesophyll apoplast and move to the epidermis along an extracellular route. The third is a vein extension pathway which provides a diffusional pathway for ions to the epidermis. A testable hypothesis for the roles of the pathways in supplying solutes to the mesophyll and epidermis is proposed and the implications of each of these pathways for transport systems in individual cell types is discussed.
We tested the hypothesis that the transport of carbon to developing pea ovules is controlled by the water potential of the seed coat, in both the short-term (minutes to hours) and long-term (days). At 14 d after anthesis, when the embryo just fills the seed coat, the osmotic pressure of seed coat apoplast solution was about 1 MPa (equivalent to 400 mOsmol kg⁻¹). Transport of carbon into perfused attached seed coats at this stage of development was monitored with radioactive carbon-11. After a small (50 mOsmol kg⁻¹) increment in the osmotic pressure of the bathing solution, transport of carbon increased abruptly, but after about 100 min it returned towards pretreatment values. Therefore, although osmotic pressure in the sink apoplast initially affected carbon import, as expected from the Mūnch hypothesis, we concluded that it was not a factor able to control import. At the same time, seed coat cell turgor, measured with the pressure probe, initially decreased but resumed pretreatment values within about 20 min, implying that turgor-regulation in the sink maintained import despite the change of apoplastic concentration.
In the longer term, from 4 to 33 d after anthesis, both the water potential and the inferred turgor of the cells of the seed coat approached zero so that the driving force for influx increased, although the rate of carbon influx was declining. Therefore, despite the importance for carbon inflow of turgor in sieve tubes in the sink, the turgor of the entire tissue was not a factor which varied to control import via any direct effect on pressure gradients in the sieve tubes.
Regulation concerns the flow of information. It can primarily be distinguished from the flow of energy. Changes in the rate of a process can take place in response to an inflow of either, but it seems likely that in biological systems the inflow of information would be specific and integrative, while the inflow of energy would simply impose a more general limitation under certain conditions.
The dry matter and carbohydrate contents of intact growing ‘Sonia’ rose corollas were measured from an immature bud to full expansion of the petals. Reducing sugars and starch, but not sucrose, accumulated throughout most of the corolla development. These findings were compared with the carbohydrate changes in the corollas of flowers cut at different stages and allowed to age with their stems either in water or in a sucrose-containing solution. For a few days after cutting the carbohydrate metabolism of the cut flower roughly paralleled that of the intact flower until starch hydrolysed to maintain the soluble carbohydrate pool. Feeding with the sucrose solution maintained the soluble carbohydrate levels and retarded the hydrolysis of starch.
The cut flowers were fed with ¹⁴C-sucrose and the labelled metabolites in the leaves and flowers were analysed. Active incorporation of ¹⁴C into ethanol-soluble carbohydrates, starch and ethanol-insoluble material was found indicating that an active anabolic phase precedes the catabolic phase during the senescence of the cut flower. The findings are discussed in relation to the source-sink hypothesis of flower development, with regard to the senescence and growth of the corollas of cut and intact flowers respectively.
A study was conducted to determine the distribution of sugars in vacuoles, cytoplasm, and free space in apples (Malus domestica Bork) picked at the immature and mature stage of maturity. The volumes of free space and air space were 13.4% and 14.5%, respectively, in immature fruit, and 14.6% and 25.6%, respectively, in mature fruit. The inner cellular volume (vacuole + cytoplasm) was 72% and 60% for immature and mature fruit, respectively. About 90% of each sugar (glucose, fructose, sucrose, and sorbitol) was found in the vacuole. The concentration of total sugar in the inner cell or free space was 326 or 128 m m each in immature fruit and 937 or 406 m m each in mature fruit. Permeability to sugars across the plasma membrane and tonoplast also increased with fruit maturation, 7- to 30-fold for the tonoplast and 4- to 5-fold for the plasma membrane in mature compared to immature fruit. Cells in immature fruit apparently enlarge through higher turgor pressure from sequestering of sugars into vacuoles, and cease to enlarge in mature fruit as the amount of sugar unloading into the fruit is reduced due to the accumulation of sugar in the free space or cytoplasm.
An unknown sugar-like compound other than glucose, fructose, sucrose and myo-inositol was detected in the ethanol extract of carnation (Dianthus caryophyllus L.) leaves and isolated using high performance liquid chromatography. The isolated compound was identified as D-(+)-chiro-inositol monomethylether (pinitol) by 1H-NMR and 1C-NMR spectra. Pinitol was the most abundant sugar in the leaf and also was present in stem, petal and the remaining part of flower in large amounts in 4 cultivars tested. In petals, the pinitol content remained constant during flower bud development on a fresh weight basis, but the organ pinitol content increased markedly. The pinitol content was also high in the other parts of the flower. These findings suggest that pinitol, a major sugar constituent, contributes to the bud growth and subsequent petal opening in the carnation together with other metabolic sugars, such as glucose and sucrose.
Changes in water relations, carbohydrate contents, and acid invertase activity in expanding gladiolus perianths on cut stems were studied.1. The specific rate of elongation of the perianth was fastest just before anthesis, but slowed down while the floral organs unfolded; it approached zero as the perianth became fully expanded.2. Pressure potential of tissue water was high while the perianth was growing rapidly.3. Fructose and glucose were the predominant soluble sugars in the perianth. These solutes were considered to contribute to the low osmotic potential of perianth tissues during their elongation process.4. Acid invertase activity of perianth tissue was correlated to the specific rate of elongation. There was no correlation between the enzyme activity and the growth rate when the perianth was wilting.5. Starch in florets was considered to be the primary source of soluble carbohydrates which contribute to the early stages of flower expansion. 6. At the wilting stage, soluble sugars were probably translocated from the perianth to other organs.
Effects of pulse treatment with silver thiosulfate complex (STS), sucrose and their combination on the quality and vase life of cut Eustoma grandiflorum flowers were investigated. Cut Eustoma flowers with two open florets and four buds were treated with 0.2 mM STS, 4% sucrose and 0.2 mM STS combined with 4% sucrose and kept at 23°C, 70% relative humidity in the dark for 20 h. The vase life of cut flowers is considered to be from harvest to when less than two open florets are subtended with erect pedicels. Treatment with STS plus sucrose and sucrose alone extended vase life, advanced bud opening, and increased anthocyanin concentration in the colored parts of petals more than did STS alone. These results indicate that pulse treatments including sucrose are more effective than STS alone to improve the quality of cut, floret-bearing Eustoma flowers which are not highly sensitive to ethylene.
There have been few reports on the morphology of flower opening, despite its horticultural significance. It is not clear when cell division stops during rose petal development or what changes occur in cell morphology. This study aims to clarify the details of cell morphological changes during rose petal development. Rose (Rosa hybrida L. 'Sonia') petals were sampled in six flower bud stages. Cell morphological changes were observed by light microscopy, transmission and scanning electron microscopy using cross sections of the petals, and the number of epidermal cells was measured using Nomarski differential interference contrast microscopy. The number of epidermal cells increased with flower opening, but the rate of increase in the number of abaxial epidermal cells slowed down at an earlier stage than in adaxial epidermal cells. The increase in the epidermal cell area was much more rapid in later stages compared with the increase in cell number, suggesting that petal growth in later stages is mainly due to cell expansion. During flower opening, the unique expansion of spongy parenchyma cells produced large air spaces. Epidermal cells of the upper part showed obvious lateral expansion. In particular, marked expansion of adaxial epidermal cells with enlargement of the central vacuole was observed. Differences in the patterns of cell expansion among cell types and locations would contribute to the reflex of petals during rose flower opening. JSHS
チオ硫酸銀錯塩（STS），1-メチルシクロプロペン（1-MCP）およびスクロース処理がブルースター切り花の品質保持に及ぼす影響を検討した．5%あるいは10%スクロース処理を行ったところ，品質保持期間が延長したが，葉に薬害が発生した．5%スクロース，STSおよび両者を組み合わせた処理を行ったところ，スクロースとSTSを組み合わせることにより，単独処理よりも品質保持効果が高まったが，薬害が発生した．スクロース濃度を3%とし，STSと組み合わせた処理を行ったところ，品質保持効果が得られ，薬害も発生しなかった．一方，1-MCPに花持ち延長効果は認められなかった．3%スクロースとSTSを低温・暗黒条件下で処理しても品質保持効果が得られた．
An unidentified carbohydrate was isolated from sweet pea (Lathyrus odoratus L. cv. Diana) petals using HPLC. The isolated compound was identified as L-1-O-methyl-myo-inositol, called L-bornesitol, using H-1-NMR, C-13-NMR, and CI-Ms. L-Bornesitol was distributed in all organs at high concentrations. L-Bornesitol concentration of petals gradually decreased during flower bud development, but the L-bornesitol content increased by about 5 times.
A carbohydrate other than sucrose, glucose, fructose and myo-inositol was detected in sepal extracts of Delphinium. This compound was identified as mannitol by 1H-NMR. Mannitol was the major carbohydrate in all examined organs: the sepal, the other parts of the flower, the stem and leaves. Mannitol as well as glucose (both at 0.55 M), fed to cut Delphinium flowers, similarly delayed the abscission of sepals. 3-O-methyl glucose (3-OMG) and polyethylene glycol 200 at the same molar concentrations had no such effect. The treatment with glucose markedly increased the concentrations of glucose and fructose in the sepals without changing the concentrations of sucrose and mannitol. On the other hand, the treatment with mannitol increased the concentrations of glucose and fructose in addition to mannitol in the sepals, suggesting that mannitol is metabolized in Delphinium flowers. The treatment with 3-OMG increased the concentration of 3-OMG but not other carbohydrates. Mannitol and glucose similarly delayed the increase in ethylene production in flowers, but 3-OMG did not. The sensitivity to ethylene was similarly reduced by the treatment with glucose and mannitol, but not by 3-OMG. These results suggest that the treatment with mannitol, a major carbohydrate in Delphinium, delayed the abscission of sepals by reducing the sensitivity to ethylene. Mannitol further acted, not merely as an osmolyte, but as an apparent source for carbohydrate metabolism in the flower.
Certain inorganic salts like KNO3, KCl, K2SO4, Ca(NO3)2 and NH4NO3 extend longevity of cut carnation flowers. The effect of KNO3 was studied in some detail. There is an osmotic adjustment in response to KNO3 treatment. The osmotic concentration change occurred in the external as well as in the internal compartments. The osmotic concentration change in the external compartment is well correlated with extension of longevity. The effect of KNO3 on the sensitivity to ethylene, and its significance in delaying senescence is discussed.
Nitrogen metabolism including nitrate reductase (EC 1.6.6.1), glutamate dehydroge-nase (EC 1.4.1.2) and glutamate-oxalacetate aminotransferase (EC 2.6.1.1) activities were studied during growth of petals taken from carnation flowers (Dianthus caryophyllus L. cv. Sir Arthur) together with senescence parameters (lipid hydroper-oxides, soluble amino acids and permeability). A slight decline in nitrogen percentage on a dry weight basis was found together with a sharp decrease in nitrate reduct-ase, glutamate-oxalacetate aminotransferase and glutamate dehydrogenase activities during the maximum growth phase, which was characterized by increase in respiration, dry weight, length, organic nitrogen and DNA per petal. Changes generally associated with senescence, like lipid hydroperoxide and soluble ammo nitrogen accumulation and increases in permeability began to appear already during early growth. The results indicate that permeability and proteolysis may be closely related. The possible significance of the decrease in nitrogen percentage and enzyme activities during growth of petals is discussed.
We found that the corolla of petunia (Petunia hybrida Vilm.) could be conspicuously enlarged by the separate application of three cytokinins: forchlorfenuron (CPPU), N 6 -benzylaminopurine (BA), and zeatin. To obtain the same enlargement as that achieved by CPPU, approximately 30 and 900 times the concentration of BA and zeatin, respectively, were required. CPPU at 3.2 mmol/L increased the limb area of the corollas of 15 cultivars to between 1.3 and 2.4 times (1.8 times on average) the size of the control area. The increase was negatively correlated (R = 0.58) with the ''genetic'' limb area (i.e., that of the untreated plant). The enlargement of the corolla caused by cytokinin application was mainly attributed to an increase in cell number in most cultivars. This increase resulted from a high rate of cell proliferation and from prolongation of the cell proliferation phase during corolla development. This anatomical change caused by cytokinin application was similar to the anatomical difference among cultivars because genetic differences in limb area resulted mainly from differences in cell number.
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.
Two unidentified soluble carbohydrates were isolated from chrysanthemum (Dendranthema x grandiflorum (Ramat.) Kitamura) leaves using HPLC. The compounds were identified as 1 L-chiro-inositol, called L-inositol (1) and scyllo-inositol, called scyllitol (2) from the results of 1H-NMR, 13C-NMR, and CI-MS spectra. L-Inositol and scyllitol were distributed in four cultivars tested. L-Inositol concentration of petals gradually decreased during the flower bud development, but the L-inositol content increased by about 7 times. Scyllitol was detected only at an early stage of flower bud.
Dry weight, water content, soluble carbohydrate content, and carbohydrate composition of daylily (Hemerocallis hybrid cv Cradle Song) flower petals were monitored in the 3 d leading up to full opening and in the first day of senescence. Timing of events was related to the time (hour 0) when flower expansion was 60% complete. Petal dry weight increased linearly from hour -62 (tight bud) to hour 10 (fully developed flower), then fell rapidly to hour 34 as senescence advanced. Increase in water content was proportional to dry weight increase from hour -62 to hour -14, but was more rapid as the bud cracked and the flower opened, giving an increase in fresh weight/dry weight ratio. Soluble carbohydrate was 50% of petal dry weight up to hour 10, then decreased during senescence to reach 4% by hour 34. Up until hour -14, fructan accounted for 80% of the soluble carbohydrate in the petals, whereas hexose accounted for only 2%. Fructan hydrolysis started just prior to bud crack at hour -14, reaching completion by hour 10 when no detectable fructan remained, and fructose plus glucose accounted for more than 80% of the total soluble carbohydrate. The proportion of sucrose remained constant throughout development. Osmolality of petal cell sap increased significantly during fructan hydrolysis, from 0.300 to 0.340 osmolal. Cycloheximide applied to excised buds between hour -38 and hour -14 halted both fructan hydrolysis and flower expansion. The findings suggest that onset of fructan hydrolysis, with the concomitant large increase in osmoticum, is an important event driving flower expansion in daylily.
2-C-methyl-D-erythritol, a soluble carbohydrate that is not ubiquitously found in higher plants, was detected in the ethanol extract from Phlox subulata petals and isolated using HPLC. The isolated compound was identified by 1H-NMR, 13C-NMR and Cl-MS spectra. 2-C-methyl-D-erythritol was a major soluble carbohydrate in petals, leaves and stems. In petals, the concentration of 2-C-methyl-D-erythritol markedly increased during flower development and opening and was similar in concentration to glucose, a ubiquitous metabolic sugar. This suggests that 2-C-methyl-D-erythritol may contribute to flower opening in association with glucose in the P. subulata.
In developing tomato (Lycopersicon esculentum Mill.) fruit, starch levels reach a peak early in development with soluble sugars (hexoses) gradually increasing in concert with starch degradation. To determine the enzymic basis of this transient partitioning of carbon to starch, the activities of key carbohydrate-metabolizing enzymes were investigated in extracts from developing fruits of three varieties (cv VF145-7879, cv LA1563, and cv UC82B), differing in final soluble sugar accumulation. Of the enzymes analyzed, ADPglucose pyrophosphorylase and sucrose synthase levels were temporally correlated with the transient accumulation of starch, having highest activities in cv LA1563, the high soluble sugar accumulator. Of the starch-degrading enzymes, phosphorylase levels were fivefold higher than those of amylase, and these activities did not increase during the period of starch degradation. Fiften percent of the amylase activity and 45 to 60% of the phosphorylase activity was localized in the chloroplast in cv VF145-7879. These results suggest that starch degradation in tomato fruit is predominantly phosphorolytic. The results suggest that starch biosynthetic capacity, as determined by levels of ADPglucose pyrophosphorylase rather than starch degradative capacity, regulate the transient accumulation of starch that occurs early in tomato fruit development. The results also suggest that ADPglucose pyrophosphorylase and sucrose synthase levels correlated positively with soluble sugar accumulation in the three varieties examined.