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Carnation ( Dianthus caryophyllus L. cv. White Sim) petal discs were radiolabelled with [P]orthophosphate and the lipids were extracted and analysed by thin-layer chromatography and autoradiography. Phospholipids were identified by co-migration with standards using thin-layer chromatography with different solvent systems. Results showed that [P]orthophosphate was rapidly incorporated into the minor lipids phosphatidic acid (PtdOH), phosphatidylinositol monophosphate (PtdInsP) and phosphatidylinositol bisphosphate (PtdInsP), and relatively slowly into the structural lipids phosphatidylcholine, -ethanolamine, -glycerol and -inositol. Pulse-chase experiments revealed that the label was rapidly lost from PtdOH, PtdInsP and PtdInsP while the structural lipids remained radiolabelled. The amount of PtdInsP and PtdInsP was found to constitute 0.45% and 0.013%, respectively, of the total phospholipids, on a molar basis. Together these results show that the turnover of the chemically low-abundant polyphosphoinositides is relatively high compared with the major structural phospholipids. Phosphatidylinositol monophosphate was further characterized by showing that it incorporates myo[H]inositol and that its major fatty-acid constituents are palmitic acid and linoleic acid. Furthermore, we present evidence for the presence of both phosphatidylinositol 3-phosphate and phosphatidylinositol 4-phosphate isomers. The significance of these results is discussed with respect to plant phosphoinositide signal transduction. [ABSTRACT FROM AUTHOR]

Flavonoid analysis and supplementation experiments with dihydroflavonols and leucocyanidin on two cyanic, two acyanic and one white/red-variegated flowering strain of Dianthus caryophyllus (carnation) showed that in the acyanic strains recessive alleles ( aa) of the gene A interrupt the anthocyanin pathway between dihydroflavonols and leucoanthocyanidins. The instability in the variegated strain involves the same step and is obviously caused by the multiple allele a. In confirmation of these results, dihydroflavonol 4-reductase activity could be demonstrated in enzyme extracts from cyanic flowers and cyanic parts of variegated flowers but not in preparations from acyanic flowers or acyanic parts. The enzyme catalyzes the stereospecific reduction of (+)dihydrokaempferol to (+)-3,4-leucopelargonidin with NADPH as cofactor. A pH optimum around 7.0 and a temperature optimum at 30° C was determined, but the reduction reaction also proceeded at low temperatures. (+)Dihydroquercetin and (+)dihydromyricetin were also reduced to the respective flavan-3,4-cis-diols by the enzyme preparations from carnation flowers, and were even better substrates than dihydrokaempferol. [ABSTRACT FROM AUTHOR]

The relationship between ethylene production and the CN-assimilating enzyme β-cyanoalanine synthase (CAS; EC 4.4.1.9) was examined in the carnation ( Dianthus caryophyllus L.) flower. In petals from cut flowers aged naturally or treated with ethylene to accelerate senescence the several hundred-fold increase in ethylene production which occurred during irreversible wilting was accompanied by a one- to twofold increase in CAS activity. The basal parts of the petal, which produced the most ethylene, had the highest CAS activity. Studies of flower parts (styles, ovaries, receptacles, petals) showed that the styles had a high level of CAS together with the ethylene-forming enzyme (EFE) system for converting 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. The close association between CAS and EFE found in styles could also be observed in detached petals after induction by ACC or ethylene. Treatment of the cut flowers with cycloheximide reduced synthesis of CAS and EFE. The data indicate that CAS and ethylene production are associated, and are discussed in relation to the hypothesis that CN is formed during the conversion of ACC to ethylene. [ABSTRACT FROM AUTHOR]

Several lines of evidence indicate that the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene by microsomal membranes from carnation flowers is attributable to hydroperoxides generated by membrane-associated lipoxygenase (EC 1.13.11.12). As the flowers senesce, the capability of isolated microsomal membranes to convert ACC to ethylene changes. This pattern of change, which is distinguishable from that for senescing intact flowers, shows a close temporal correlation with levels of lipid hydroperoxides formed by lipoxygenase in the same membranes. Specific inhibitors of lipoxygenase curtail the formation of lipid hydroperoxides and the production of ethylene from ACC to much the same extent, whereas treatment of microsomes with phospholipase A, which generates fatty-acid substrates for lipoxygenase, enhances the production of hydroperoxides as well as the conversion of ACC to ethylene. Lipoxygenase-generated lipid hydroperoxides mediate the conversion of ACC to ethylene in a strictly chemical system and also enhance ethylene production by microsomal membranes. The data collectively indicate that the in-vitro conversion ACC to ethylene by microsomal membranes of carnation flowers is not reflective of the reaction mediated by the native in-situ ethylene-forming enzyme. [ABSTRACT FROM AUTHOR]

The oxidation of carbohydrate by the pentose-phosphate pathway in the shoot apical meristem and developing leaf primordia of Dianthus chinensis was assessed by measuring the activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.49). On a kg dry weight h basis, activity rose from 250 mmol in the apical meristem to 550 mmol in the first two leaf primordia and then declined to 350 mmol in the sixth pair of leaf primordia, and finally to 200 mmol in leaves just emerged from the shoot bud. Measurements of activity in the sixth leaf pair from the apex showed differential distribution in leaf tissues. Epidermal and mesophyll tissue had about the same activity as whole-leaf tissue, but vascular bundles had 70% greater activity. Within the vascular tissue, activity in the phloem was twice as high as in the xylem. When activity was expressed on a per-cell basis, there was a continuous increase from 20 fmol in the apex to 2 pmol in the sixth leaf pair. Activity on a per unit cell volume basis showed that cells of the apical meristem and the epidermis, mesophyll and xylem of the sixth leaf pair had similar values, about 30 amol; only the two youngest pairs of primordia and the phloem had values two or three times this amount. [ABSTRACT FROM AUTHOR]

Chalcone synthase activity was demonstrated in enzyme preparations from flowers of defined genotypes of Dianthus caryophyllus L. (carnation). In the absence of chalcone isomerase activity, which could be completely excluded by genetic methods, the first product formed from malonyl-CoA and 4-coumaroyl-CoA proved to be naringenin chalcone, followed by formation of naringenin as a result of chemical cyclization. In the presence of chalcone isomerase activity, however, naringenin was the only product of the synthase reaction. In vitro, both 4-coumaryl-CoA and caffeoyl-CoA were found to be used as substrates for the condensation reaction with respective pH optima of 8.0 and 7.0. The results of chemogenetic and enzymatic studies, however, showed that in vivo only 4-coumaroyl-CoA serves as substrate for the formation of the flavonoid skeleton. In confirmation of these results, an NADPH-dependent microsomal 3′-hydroxylase activity could be demonstrated, catalyzing hydroxylation of naringenin and dihydrokaempferol in 3′-position. Furthermore, a strict correlation was found between 3′-hydroxylase activity and the gene r which is known to control the formation of 3′, 4′-hydroxylated flavonoid compounds. [ABSTRACT FROM AUTHOR]

Isolated membranes from the petals of senescing carnation flowers ( Dianthus caryophyllus L. cv. White-Sim) catalyze the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. A microsomal membrane fraction obtained by centrifugation at 131,000 g for 1 h proved to be more active than the membrane pellet isolated by centrifugation at 10,000 g for 20 min. The ethylene-producing activity of the microsomal membranes is oxygen-dependent, heat-denaturable, sensitive to n-propyl gallate, and saturable with ACC. Corresponding cytosol fractions from the petals are incapable of converting ACC to ethylene. Moreover, the addition of soluble fraction back to the membrane fraction strongly inhibits the ACC to ethylene conversion activity of the membranes. The efficiency with which isolated membranes convert ACC to ethylene is lower than that exhibited by intact flowers based on the relative yield of membranes per flower. This may be due to the presence of the endogenous soluble inhibitor of the reaction, for residual soluble fraction inevitably remains trapped in membrane vesicles isolated from a homogenate. [ABSTRACT FROM AUTHOR]

Carnations were treated with a silver thiosulphate complex to prevent wilting of the flowers. The ultrastructural localization of silver and sulphur in the receptacle tissue was investigated by electron microscopy. Electron-dense deposits were present in the receptacle tissue. Coarse-grained deposts (diam. 60-100 nm) were predominantly observed at the inner side of the cell wall, whereas fine-grained deposits (diam. 20-60 nm) were predominantly present inside the cell-wall region and in the intercellular spaces. These particles were analyzed for chemical elements by X-ray analytical electron microscopy (Philips EM 400 plus Edax energy dispersive analyzer, type 711). In both types of deposits, the presence of silver and sulphur was verified. Point analysis revealed that in both precipitates the S/Ag ratio was of the same order. [ABSTRACT FROM AUTHOR]

Silver, applied as silverthiosulphate, completely blocked the ethylene surge preceding the wilting of the petals. As a consequence, vase life was extended by nearly 100%. In addition, a pretreatment with silverthiosulphate caused the flowers to become insensitive to an ethylene treatment. [ABSTRACT FROM AUTHOR]

The mobility of different ionic forms of silver (Ag) has been studied using semiconductor radiation detectors. Silver, applied as silvernitrate (2mM), moves upward in the stems of cut carnations ( Dianthus caryophyllus L.) at about 3 cm day. This transport has the characteristics of a chromatographic exchange transport, but is not promoted by the addition of other cations (K or Ca). The silverthiosulphate anionic complex is transported at the same speed as [P]phosphate (about 2 m h); orders of magnitude faster than Ag. The antiethylene action of silver is preserved in this complex, as shown by a significant improvement of the longevity of carnation flowers in the presence or absence of ethephon, even after a short treatment with the silverthiosulphate complex. Analysis of the silver content of different flower parts after a silverthiosulphate treatment shows a distinct accumulation in the receptacle, possibly associated with the antiethylene action. [ABSTRACT FROM AUTHOR]

Production of endogenous ethylene from the styles, ovary and petals of pollinated and unpollinated flowers of Dianthus caryophyllus L. was measured. The rate of ethylene production of cut, unpollinated flowers aged in water at 18°C was low until the onset of petal wilting, when a rapid surge of ethylene occurred in all tissues. The flower ethylene production was evolved mostly from the styles and petals. The bases of petals from unpollinated, senescing flowers evolved ethylene faster and sometimes earlier than the upper parts. Treatment of cut flowers with propylene, an ethylene analogue, accelerated wilting of flower petals and promoted endogenous ethylene production in all flower tissues. Pollination of intact flowers also promoted endogenous ethylene production and caused accelerated petal wilting within 2-3 days from pollination. Although the data are consistent with the hypothesis that ethylene forms a link between pollination of the style and petal wilting, in the unpollinated flower the style and petals can evolve a surge of ethylene independently of each other, about the time when the petals irreversibly wilt. The results are discussed in relation to the role of ethylene in flower senescence. [ABSTRACT FROM AUTHOR]