Effects of Ethylene and Sucrose on Translocation of Dry Matter and 14C-Sucrose in the Cut Flower of the Glasshouse Carnation (Dianthus caryophyllus) During Senescence

The translocation and distribution of dry matter were studiedin the floral and vegetative parts of the cut carnation duringsenescence. The change in dry weights of the tissues and theamount of radioactivity recovered from them after feeding with¹⁴C-sucrose were measured. Treatments with ethylene and sucrosewere used to alter the rate of senescence of the flowers. Sucrosemoved through the stem relatively unchanged but was rapidlyinverted and metabolized in the petals. During natural ageing,¹⁴C moved from the stem to the flower and the movement was enhancedby exogenous sucrose, which also reduced the loss of dry matterin the petals and promoted their growth. Treatment with ethylenecaused petals to wilt and lose dry weight, and ovaries to enlargeand increase in dry weight. The distribution of radioactivityin flowers fed with 14C-sucrose before and after ethylene treatmentsupported the observation that dry matter was translocated betweenthe flower parts. The results indicate that a change in thesource-ink relationships of the flower parts contributes tothe factors that determine the rate of flower senescence.     

保鲜剂对香石竹切花的保鲜效应

研究了保鲜剂(4％蔗糖 200 mg／L8-HQ 50 mg／L6-BA及4％蔗糖 0．1％明矾 0．02％尿素 0．02％NaCl)对香石竹切花的保鲜效应。结果表明,保鲜剂4％蔗糖 200 mg／L8-HQ 50 mg／L6-BA能明显地缓解切花水分胁迫,改善体内水分平衡,延缓切花衰老,延长切花的寿命。     

Ultrastructural Changes in the Petals of Senescing flowers of Dianthus caryophyllus L.

Ultrastructural changes associated with carnation petal senescencewere investigated using ethylene levels of individual petalsas a physiological monitor of the senescence process. Limitedvacuolar and cytoplasmic vesiculation was observed in pre-senescentpetals which became more extensive in pre-climacteric tissues,along with dilation of the outer mitochondrial membrane. Climactericmesophyll tissue was characterized by widespread cytolysis.Intact cells possessed a highly reduced cytoplasm and vacuoleswith electron-dense deposits. Degenerative changes became evidentin the vasculature at this stage. These included occlusion ofthe sieve plate, and membrane abnormalities in the companioncells. Post-climacteric tissue was characterized by looseningof wall fibrillar structure in the vasculature, the appearanceof intracellular cytoplasmic debns and cells completely devoidof contents. These changes are discussed in relation to developmentalregulation on the one hand, and increasing levels of membranedisorgamsation on the other, leading to a possible ‘errorcatastrophe’ and final senescence. Dianthus caryophyllus L. cv., White Sim, carnation, Petal senescence, ultrastructure, ethylene, climacteric vacuoles, membranes, wall lysis     

Isozymes of Superoxide Dismutase in Mitochondria and Peroxisomes Isolated from Petals of Carnation (Dianthus caryophyllus) during Senescence

The balance between reactions involving free radicals and processes which ameliorate their effect plays an important role in the regulation of plant senescence. In this study a method was developed to isolate peroxisomes and mitochondria from carnation (Dianthus caryophyllus L. cv Ember) petals. Based on electron microscopy and marker enzyme levels, the proportion of peroxisomes to mitochondria increases during senescence. The superoxide dismutase (SOD) content of these fractions was examined. Mitochondria and peroxisomes were shown to contain two electrophoretically distinct SODs, a manganese-, and an ironcontaining SOD. The Mn- and Fe-SOD were found to have relative molecular weights of 75,000 and 48,000 and isoelectric points of 4.85 and 5.00, respectively. The presence of a Fe-SOD in mitochondria and peroxisomes is unique because this enzyme is usually located in chloroplasts. The activity of these two isoenzymes decreased during senescence in mitochondria but remained high in peroxisomes from senescent tissue. It is suggested that peroxisomes play a particular role in the process of senescence.     

西花蓟马在康乃馨不同品种上的田间分布

调查西花蓟马Frankliniella occidentalis(Pergande)在10个康乃馨(Dianthus caryophyllus)品种上的发生与分布,比较花朵颜色与气味对西花蓟马寄主选择性的影响。结果表明,花朵上的西花蓟马数量在不同品种间存在显著差异。花朵颜色是影响西花蓟马寄主选择的主要原因,而花朵气味也能影响西花蓟马对寄主的选择性。     

溴代十六烷基吡啶对香石竹切花的保鲜效应

研究切花瓶插液中加入0．3g．L^-1季铵盐化合物溴代十六烷基吡啶（CPB）后,瓶插液中微生物密度和切花茎杆基部病原菌分离频率下降,切花后期的水分平衡和鲜重能较好地维持,花冠直径增大,观赏寿命延长。     

Regulation of Senescence in Carnation (Dianthus caryophyllus): Effect of Abscisic Acid and Carbon Dioxide on Ethylene Production

Abscisic acid hastened senescence of carnation flowers and this was preceded by stimulation of accelerated ethylene production. Carbon dioxide delayed the onset of autocatalytic ethylene production in flowers regardless of treatment with abscisic acid. Flowers exhibited a low and transient climacteric of ethylene production without wilting while in 4% carbon dioxide and underwent accelerated ethylene production culminating in wilting when removed from carbon dioxide. Hypobaric ventilation, which lowers ethylene to hyponormal levels within tissues, extended flower longevity and largely negated enhancement of senescence by abscisic acid. Supplementing hypobarically ventilated flowers with ethylene hastened senescence irrespective of abscisic acid treatment. Collectively, the data indicate that abscisic acid hastens senescence of carnations largely as a result of advancing the onset of autocatalytic ethylene production.     

The Effect of Inorganic Salts on the Senescence of Dianthus caryophyllus Flowers

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.     

Inhibition by 1-Aminocyclobutane-l-Carboxylate of the Activity of 1-Aminocyclopropane-l-Carboxylate Oxidase Obtained from Senescing Petals of Carnation {Dianthus caryophyllus L.) Flowers

We partially purified 1-aminocyclopropane-l-carboxy-late (ACC)oxidase from senescing petals of carnation {Dianthus caryophyllusL. cv. Nora) flowers and investigated its general characteristics,and, in particular, the inhibition of its activity by ACC analogs.The enzyme had an optimum pH at 7-7.5 and required Fe²⁺, ascorbateand NaHCO₃ for its maximal activity. The K_m for ACC was calculatedas 111-125 µM in the presence of NaHCO₃. Its M_r was estimatedto be 35 and 36 kDa by gel-filtration chromatography on HPLCand SDS-PAGE, respectively, indicating that the enzyme existsin a monomeric form. These properties were in agreement withthose reported previously with ACC oxidases from different planttissues including senescing carnation petals. Among six ACCanalogs tested, l-aminocyclobutane-l-carboxylate (ACBC) inhibitedmost severely the activity of ACC oxidase from carnation petals.ACBC acted as a competitive inhibitor with the K_i of 20-31 µM.The comparison between the K_m for ACC and the K_i for ACBC indicatedthat ACBC had an affinity which was ca. 5-fold higher than thatof ACC. Whereas ACC inactivated carnation ACC oxidase in a time-dependentmanner during incubation, ACBC did not cause the inactiva-tionof the enzyme. Preliminary experiments showed that ACBC andits N-substituted derivatives delayed the onset of senescencein cut carnation flowers. (Received August 19, 1996; Accepted November 26, 1996)     

Translocation of 14C-sucrose in Relation to Changes in Carbohydrate Content in Rose Corollas Cut at Different Stages of Development

The dry matter and carbohydrate contents of intact growing ‘Sonia’rose corollas were measured from an immature bud to full expansionof the petals. Reducing sugars and starch, but not sucrose,accumulated throughout most of the corolla development. Thesefindings were compared with the carbohydrate changes in thecorollas of flowers cut at different stages and allowed to agewith their stems either in water or in a sucrose-containingsolution. For a few days after cutting the carbohydrate metabolismof the cut flower roughly paralleled that of the intact floweruntil starch hydrolysed to maintain the soluble carbohydratepool. Feeding with the sucrose solution maintained the solublecarbohydrate levels and retarded the hydrolysis of starch. The cut flowers were fed with ¹⁴C-sucrose and the labelled metabolitesin the leaves and flowers were analysed. Active incorporationof ¹⁴C into ethanol-soluble carbohydrates, starch and ethanol-insolublematerial was found indicating that an active anabolic phaseprecedes the catabolic phase during the senescence of the cutflower. The findings are discussed in relation to the source-sinkhypothesis of flower development, with regard to the senescenceand growth of the corollas of cut and intact flowers respectively.     

Effect of drought and prolonged refrigeration on senescence in cut carnation (Dianthus caryophyllus)

Severe water stress (40 and 50 h without water at 23°C) and long periods of refrigeration (4 and 5 weeks at 0°C) caused the peak of ethylene production by cut carnation flowers to appear soon after the return to normal conditions. Water stress caused a decrease in ψosm, but this increased back to the initial value on return to normal conditions. Accelerated wilting and massive ion leakage, probably a result of the Joss of membrane integrity, was associated with this premature burst of ethylene. Large amounts of acetaldehyde and ethanol accumulated during prolonged refrigeration (3, 4 or 5 weeks at 0°C). This accumulation of toxic metabolites may explain why the refrigeration of cut flowers for long periods causes a rapid wilting on return to normal conditions.     

Observations on the Growth of Carnation (Dianthus caryophyllus L.) in Natural and Long Days

Observations were made on the growth and development of carnationsgrown in containers under natural or 24 h days. The number ofleaf pairs produced before flower initiation and the final lengthof each flowering stem were affected by the date at which theshoot appeared and its position on the plant. Dusk-to-dawn lighting reduced the number of axillary shootsin each generation but increased their rate of development.This resulted in similar numbers of flowers being produced inboth treatments. Dianthus caryophyllus L., Carnation, growth, flowering, day length     

Evidence for thiol-induced enhanced in situ translocation of 14C-sucrose from source to sink in Brassica juncea

The translocation of ¹⁴C-sucrose to the different parts of the mustard (Brassica juncea) crop has been evaluated in the context of understanding the source to sink relationship in the thiol-induced enhanced crop yield. The foliar application of thiols like TU, TGA and DTT to the plant gave maximum sucrose phosphate synthase activity, which was found to have direct correlation with the movement of sucrose. The distribution pattern of ¹⁴C-sucrose follows the path from internode and node to pod via leaf. The translocation of ¹⁴C-sucrose was found to be a light dependent process. Among the nucleotides ATP and GTP, only ATP was able to promote the translocation and GTP was ineffective. In this unique in situ tracer experiment using ¹⁴C-sucrose, we could establish that thiols are able to enhance the translocation of sucrose from source to sink.     

Evidence for thiol-induced enhanced in situ translocation of 14C-sucrose from source to sink in Brassica juncea

The translocation of ¹⁴C-sucrose to the different parts of the mustard (Brassica juncea) crop has been evaluated in the context of understanding the source to sink relationship in the thiol-induced enhanced crop yield. The foliar application of thiols like TU, TGA and DTT to the plant gave maximum sucrose phosphate synthase activity, which was found to have direct correlation with the movement of sucrose. The distribution pattern of ¹⁴C-sucrose follows the path from internode and node to pod via leaf. The translocation of ¹⁴C-sucrose was found to be a light dependent process. Among the nucleotides ATP and GTP, only ATP was able to promote the translocation and GTP was ineffective. In this unique in situ tracer experiment using ¹⁴C-sucrose, we could establish that thiols are able to enhance the translocation of sucrose from source to sink.     

Effect of Cytokinins on Photosynthetic Pigments and Chlorophyllase Activity in in Vitro Cultures of Axillary Buds of Dianthus caryophyllus L.

The effect of benzyladenine (BA) and two phenylurea cytokinins, N-phenyl-N′-(2-chloro-4-pyridyl)urea (4-PU-30) and thidiazuron (TDZ), on the growth, photosynthetic pigment content, and activity of chlorophyllase (chlorophyll-chlorophylliodhydrolase, EC 3.1.1.14) of in vitro cultures of carnations was studied. All cytokinins caused a rise in the fresh weigth and a drop in the dry weight of leaf mass produced by the explanted buds. Both 4-PU-30 and TDZ increased the chlorophyll content and this correlated with changes in chlorophyllase activity. The effect of 4-PU-30 and TDZ was similar to that caused by BA but at 10-fold or 100-fold lower concentrations. The application of higher concentrations of the phenylurea cytokinins caused an increase in the chlorophyll a/chlorophyll b ratio. However, at equimolar concentrations, the purine and both phenylurea cytokinins had opposite effects, probably indirect and related to some malformations caused by phenylureas. 4-PU-30 increased, but TDZ decreased, photosynthetic membrane stability, which argues for a different molecular organization of the chloroplast membranes. Received February 26, 1996; accepted May 30, 1997     

不同保鲜液对郁金香切花保鲜及其贮藏的影响

 本文研究了不同保鲜液及贮藏20-40天后对郁金香切花瓶插寿命的影响。结果表明：1. 保鲜液延长了切花的插瓶保鲜时间;2. 预处理提高了开花率及开花时间;3. 经一个月以上贮藏,开花率及插瓶保鲜时间明显下降;4. 不同品种的耐贮性能不同。