The effect of aminooxyacetic acid and cytokinin combinations on carnation flower longevity

A simplified method, which utilizes a 50% senescence value (S₅₀) for the measurement of longevity, in cut carnation flowers is used to compare flower longevity. A pulsed treatment using a combination of aminooxyacetic acid (AOA), kinetin and Triton X-100 enhanced flower vase-life relative to a water control. The mixture, however, did not exhibit synergistic effects when S₅₀ values of the individual compounds were compared. A single AOA pulse treatment was as effective as the mixture. These findings held true for three carnation cultivars. With the exception of dihydrozeatin, which greatly enhanced longevity, replacement of kinetin by a range of cytokinins did not produce significantly different results from the AOA/Triton X-100 combination. Holding solution treatments gave similar trends as pulse treatments. S₅₀ values were better units to express longevity than S₁₀₀ values.Abbreviations AOA aminooxyaceticacid - BA benzyladenine - S₅₀ 50% senescence value - STS silverthiosulphate - iP isopentenyladenize - Z zeatin - DHZ dihydrozeatin     

The role of ethylene in the senescence of carnation flowers, a review

The senescence of flower petals is a highly regulated developmental process which requires active gene expression and protein synthesis. The biochemical changes associated with petal senescence in carnation flowers include an increase in hydrolytic enzymes, degradation of macro-molecules, increased respiratory activity and a climacteric-like increase in ethylene production. It is clear that the gaseous phytohormone ethylene plays a critical role in the regulation and coordination of senescence processes. Many reviews on physiology and mode of action of ethylene are available. Molecular cloning led to the isolation of genes involved in ethylene biosynthesis and action. This review describes the current status of the studies on regulation of ethylene biosynthesis and ethylene response in carnation flowers. An overview is given of studies on senescence-related gene expression and possibilities to improve postharvest longevity by genetic engineering.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - AIB -amino-isobutyric acid - AOA amino oxyacetic acid - AVG aminoathoxyvinyl glycine - DACP diazocyclopentadiene - EFE ethylene forming enzyme - MACC malonyl 1-aminocyclopropane-1-carboxylic acid - MTA 5-methylthio-adenosine - NBD 2,5 norbornadiene - ppb parts per billion - SAM S-adenosyl-methionine - STS silver thiosulphate     

Effects of 1,1-dimethyl-4-(phenylsulfonyl)semicarbazide (DPSS) on carnation flower longevity

The effects of a novel preservative for cut carnation flowers, 1,1-dimethyl-4-(phenylsulfonyl)semicarbazide (DPSS), were investigated. DPSS extended the vase life of cut carnation flowers not only by continuous treatment but pulse treatment as well. This inhibition of senescence by DPSS appeared to depend on that of ethylene production in carnation flowers. DPSS provided no protection from the action of ethylene nor did it inhibit 1-aminocyclopropane-1-carboxylic acid (ACC) synthase. It did inhibit ACC-dependent ethylene production in carnation petal discs, suggesting possible potential for inhibiting ACC oxidase.     

Inhibition of wilting and autocatalytic ethylene production in cut carnation flowers by cis-propenylphosphonic acid

The effect of cis-propenylphosphonic acid (PPOH), a structural analoge of ethylene, on flower wilting and ethylene production was investigated using cut carnation flowers which are very sensitive to ethylene. Wilting (petal in-rolling) of the flowers was delayed by continuously immersing the stems in a 5–20 mM PPOH solution. In addition, the continuous treatment with PPOH markedly reduced autocatalytic ethylene production of the petals accompanying senescence. This reduction of autocatalytic ethylene production was considered responsible for the inhibitory effect of PPOH on flower wilting. The inhibitory activity of trans-propenylphosphonic acid (trans-PPOH), on both flower wilting and the autocatalytic ethylene production accompanying senescence was markedly lower than that of PPOH, suggesting that PPOH action is stereoselective. PPOH may be of interest as a new, water-soluble inhibitor of wilting and autocatalytic ethylene production in cut carnation flowers.     

A flower senescence-related mRNA from carnation encodes a novel protein related to enzymes involved in phosphonate biosynthesis

We have isolated a cDNA clone (pSR132) representing a mRNA which accumulates in senescing carnation flower petals in response to ethylene. In vitro translation of RNA selected by hybridization with pSR132 indicated the mRNA encoded a polypeptide of approximately 36 kDa. This was confirmed by DNA sequence analysis, which predicted a peptide composed of 318 amino acids with a calculated molecular weight of 34.1 kDa. Comparison of the predicted peptide sequence of pSR132 with other proteins compiled in the NBRF data base revealed significant homology with carboxyphosphonoenolpyruvate mutase and phosphoenolpyruvate mutase from Streptomyces hygroscopicus and Tetrahymena pyriformis, respectively. These enzymes are involved in the formation of C-P bonds in the biosynthesis of phosphonates. C-P bonds are found in a wide range of organisms, but their presence or formation in higher plants has not been investigated.     

Effect of gibberellic acid on carnation flower senescence: evidence that the delay of carnation flower senescence by gibberellic acid depends on the stage of flower development

Gibberellic acid at concentrations of 10^–5 M and 10^–4 M delayed the senescence of cut carnation flowers, when applied continuously via the stem, to flowers between the closed brush and fully open stages of development. Older flowers with reflexed petals were unresponsive. Treatment with paclobutrazol, an inhibitor of GA biosynthesis, prevented tight buds from opening fully, reduced the longevity of partially open flowers, but was ineffective when applied continuously to fully open flowers. Gibberellic acid-treated flowers did not show simultaneous petal inrolling, a known indicator of senescence, and the time to complete petal drying was extended. Gibberellic acid modified the climacteric ethylene rise in a manner consistent with the extension of longevity. These results provide evidence for a correlative role of gibberellins in flower development.Abbreviations GA₃ gibberellin A₃ - GLC gas liquid chromatography     

Roles of pollination and short-chain saturated fatty acids in flower senescence

Pollination induced an immediate increase in ethylene production in Dianthus caryophyllus and Petunia hybrida. In Cymbidium, a lag of several hours was observed. In all three species, pollination induced premature flower senescence. Treatment of the stigmatic surface with aminoethoxyvinylglycine prior to pollination effectively blocked the increase in ethylene production and alleviated the detrimental effect of pollination on flower life.In all three tested species, octanoic and decanoic acids, when applied to the stigmatic surface, had no effect on ethylene production and flower life. In isolated Cymbidium lips placed with their cut base in solutions containing these fatty acids, no effects on red colouration, ethylene production, and ethylene forming enzyme activity were observed. In addition, ethylene sensitivity of isolated lips was not affected. The putative regulatory role of short-chain saturated fatty acids in (pollination-induced) flower senescence is discussed.     

Improvement of adventitious shoot formation from carnation leaf explants

Adventitious shoot formation from leaf explants of carnation (Dianthus caryophyllus L.) was investigated. The two leaves from one node of in vitro-grown plants showed different shoot-forming potential, depending on the order in which the leaves were removed from the stem. The leaf removed second formed more shoots and also had a large amount of adhering stem tissue. Explants with equal amounts of adhering stem tissue were obtained by making two incisions through the fused leaf bases, prior to their removal, resulting in an improved shoot formation. The procedure developed for leaf explants from in vitro-grown plants was also applied to leaf explants from greenhousegrown plants. Shoot formation from leaf explants taken from greenhouse-grown plants was further improved by cutting the leaf explant longitudinally into two parts.Abbreviations BA benzyladenine - NAA -naphthaleneacetic acid     

Cytokinins in cut carnation flowers. IV effects of benzyladenine on flower longevity and the role of different longevity treatments on its transport following application to the petals

A low concentration of benzyladenine (4.44 × 10^-5 M) accelerated the senescense of cut carnation flowers. This effect could be reversed by STS-treatment but not by keeping the flowers in a holding solution containing 4% ethanol. This appears to be the first report indicating that cytokinins at a specific level may actually enhance flower senescense. The higher levels tested (1.11 × 10^-4 and 2.22 × 10^-4 M) retarded senescense, being in agreement with published results. The applied cytokynin was metabolized slowly in the petals to a compound(s) which co-chromatographed with ribosylbenzyladenine when separated by TLC and when fractionated by HPLC. In the experiments applying (¹⁴C) benzyladenine to the petals, a small degree of transport of the ¹⁴C was detected in naturally senescing (control) cut flowers and when treated with ethrel. The transported ¹⁴C was detected in both the ovaries and in the stems and co-chromatographed with benzyladenine. Where flower senescense was delayed (ethanol or STS) no movement from the petals was detected. This suggests that the cytokinin moved within the assimilate stream, along with sugars.     

Vitrification of carnation in vitro: Changes in ethylene production,ACC level and capacity to convert ACC to ethylene

Carnation tissue was allowed to vitrify in liquid culture and ethylene production, ACC content and capacity to convert ACC to ethylene were measured in comparison to tissue developing normally on solid medium. Flask atmospheres of liquid cultures accumulated ethylene at a higher rate during the first four days. Daily ethylene production by vitrifying material decreased later. Ethylene emission by vitrifying tissues always remained above controls when subcultured daily to fresh medium. Explants and microsomal preparations from vitrifying carnations converted ACC to ethylene at a higher degree from the first day in liquid medium. ACC level markedly increased in vitrifying tissues during the first two days of liquid culture. Raising the level of ethylene in the atmosphere of solid cultures did not induce vitrification symptoms nor did use of inhibitors of ethylene biosynthesis in liquid cultures prevent the process. The role of ethylene in vitrification is reappraised.     

Cytokinins in cut carnation flowers. VII. The effect of zeatin and dihydrozeatin derivatives on flower longevity

Dihydrozeatin, at 4×10^–5 M, delayed the senescence of carnation flowers while tZ, at the same concentration, accelerated it. cis-Zeatin was ineffective. The DHZ derivatives as well as the Z derivatives gave responses very similar to those observed for the parent free bases. While additional experimentation with radiolabelled derivatives is clearly called for, the similarity between the responses observed for the respective derivatives and the free bases, suggests that in the carnation flower there is a great deal of metabolic interconversion.Abbreviations DHZ dihydrozeatin - DHZR ribosyldihydrozeatin - DHZOG glucosyl-O-dihydrozeatin - DHZ9G glucosyl-9-dihydrozeatin - DHZROG glucosyl-O-ribosyldihydrozeatin - cZ cis-zeatin - tZ trans-zeatin - ZR ribosylzeatin - Z9G glucosyl-9-zeatin - ZOG glucosyl-O-zeatin - ZROG glucosyl-O-ribosylzeatin     

Ethylene biosynthetic genes are differentially expressed during carnation (Dianthus caryophyllus L.) flower senescence

Ethylene production and expression patterns of an 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (CARAO1) and of two ACC synthase (EC 4.4.1.14) genes (CARACC3 and CARAS1) were studied in floral organs of cut carnation flowers (Dianthus caryophyllus L.) cv. White Sim. During the vase life and after treatment of fresh flowers with ethylene, production of ethylene and expression of ethylene biosynthetic genes first started in the ovary followed by the styles and the petals. ACC oxidase was expressed in all the floral organs whereas, during the vase life, tissue-specific expression of the two ACC synthase genes was observed. After treatment with a high ethylene concentration, tissue specificity of the two ACC synthase genes was lost and only a temporal difference in expression remained. In styles, poor correlation between ethylene production and ACC synthase (CARAS1) gene expression was observed suggesting that either activity is regulated at the translational level or that the CARAS1 gene product requires an additional factor for activity.Isolated petals showed no increase in ethylene production and expression of ethylene biosynthetic genes when excised from the flower before the increase in petal ethylene production (before day 7); showed rapid cessation of ethylene production and gene expression when excised during the early phase of petal ethylene production (day 7) and showed a pattern of ethylene production and gene expression similar to the pattern observed in the attached petals when isolated at day 8. The interorgan regulation of gene expression and ethylene as a signal molecule in flower senescence are discussed.     

乙烯在切花衰老中的作用(综述)

切花衰老是基因表达激活和蛋白质合成受到高度调控的过程。切花衰老所伴随的生理生化变化包括水解酶活性上升、大分子物质降解、呼吸作用增强和类似呼吸跃变的乙烯合成剧增等。乙烯的生成及其作用是切花衰老研究中十分重要的内容。本文综述乙烯在切花衰老过程中调控作用的研究现状。     

Enhancement of petunia and dendrobium flower senescence by jasmonic acid methyl ester is via the promotion of ethylene production

Methyl jasmonate (JA-Me), applied to dendrobium and petunia flowers either as an aqueous solution through the cut stem or stigma, or as a gas, accelerated senescence. The rate of appearance of wilting symptoms was directly related to the amount of JA-Me applied to the flowers. JA-Me increased ethylene production by the flowers, irrespective of application method, and this effect was also proportional to the dose of the compound. In both dendrobium and petunia flowers, the JA-Me induced increases in ethylene production and 1-aminocyclopropane-1-carboxylic acid content followed similar patterns. Aminooxyacetic acid, an inhibitor of ACC-synthase, and silver-thiosulfate, an inhibitor of ethylene action, completely inhibited the effects of JA-Me. It is concluded that JA-Me enhances petunia and dendrobium flower senescence via the promotion of ACC and ethylene production.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - AOA aminooxyacetic acid - Fl flower - JA jasmonic acid - JA-Me jasmonic acid methyl ester - LOX lipoxygenase - PLase A A-type phospholipase - STS silver-thiosulfate     

High frequency somatic embryogenesis and plant regeneration in root explant cultures of carnation

Root explants excised from carnation plants maintained in vitro formed off-white, friable calluses after three weeks of culture on Murashige and Skoog (MS) medium supplemented with 1 mg l⁻¹ thidiazuron (TDZ) and 1 mg l⁻¹ α-naphthalaneacetic acid (NAA). These calluses were subsequently transferred to MS basal medium where, after an additional four weeks of culture, approximately 50% of the calluses formed somatic embryos. However, calluses formed on root explants that had been cultured on MS medium supplemented with 2,4-dichlorophenoxyacetic acid did not produce somatic embryos upon transfer to MS basal medium. Somatic embryos developed into plantlets and subsequently were grown to maturity. These results indicate that root explants have a high competence for somatic embryogenesis in carnation. J. Seo and S.W. Kim contributed equally to this work.