Expression of ethylene biosynthetic and receptor genes in rose floral tissues during ethylene-enhanced flower opening

Ethylene production, as well as the expression of ethylene biosynthetic (Rh-ACS1-4 and Rh-ACO1) and receptor (Rh-ETR1-5) genes, was determined in five different floral tissues (sepals, petals, stamens, gynoecia, and receptacles) of cut rose (Rosa hybrida cv. Samantha upon treatment with ethylene or the ethylene inhibitor 1-methylcyclopropene (1-MCP). Ethylene-enhanced ethylene production occurred only in gynoecia, petals, and receptacles, with gynoecia showing the greatest enhancement in the early stage of ethylene treatment. However, 1-MCP did not suppress ethylene production in these three tissues. In sepals, ethylene production was highly decreased by ethylene treatment, and increased dramatically by 1-MCP. Ethylene production in stamens remained unchanged after ethylene or 1-MCP treatment. Induction of certain ethylene biosynthetic genes by ethylene in different floral tissues was positively correlated with the ethylene production, and this induction was also not suppressed by 1-MCP. The expression of Rh-ACS2 and Rh-ACS3 was quickly induced by ethylene in gynoecia, but neither Rh-ACS1 nor Rh-ACS4 was induced by ethylene in any of the five tissues. In addition, Rh-ACO1 was induced by ethylene in all floral tissues except sepals. The induced expression of ethylene receptor genes by ethylene was much faster in gynoecia than in petals, and the expression of Rh-ETR3 was strongly suppressed by 1-MCP in all floral tissues. These results indicate that ethylene biosynthesis in gynoecia is regulated developmentally, rather than autocatalytically. The response of rose flowers to ethylene occurs initially in gynoecia, and ethylene may regulate flower opening mainly through the Rh-ETR3 gene in gynoecia.     

Exogenous Eethylene influences flower opening of cut roses (Rosa hybrida) by regulating the genes encoding ethylene biosynthesis enzymes

1 Introduction The simple gaseous phytohormone ethylene as apotent modulator has various roles in plant growth,development and in response to biotic and abioticstress, such as germination, fruit ripening, flower andleaf senescence, and responsiveness to pathogen attack and mechanical damage[1]. The opening and senes-cence of many kinds of flowers are correlated tightly to ethylene, including carnation, petunia, orchid and rose[2]. Generally, roses are classified as ethylene-sen-sitive, however…     

Exogenous ethylene influences flower opening of cut roses (<Emphasis Type="Italic">Rosa hybrida</Emphasis>) by regulating the genes encoding ethylene biosynthesis enzymes

The purpose of this paper is to investigate the differential responses of flower opening to ethylene in two cut rose cultivars, ‘Samantha’, whose opening process is promoted, and ‘Kardinal’, whose opening process is inhibited by ethylene. Ethylene production and 1-aminocyclopropane-1-carboxylate (ACC) synthase and oxidase activities were determined first. After ethylene treatment, ethylene production, ACC synthase (ACS) and ACC oxidase (ACO) activities in petals increased and peaked at the earlier stage (stage 3) in ‘Samantha’, and they were much more dramatically enhanced and peaked at the later stage (stage 4) in ‘Kardinal’ than control during vasing. cDNA fragments of three Rh-ACSs and one Rh-ACO genes were cloned and designated as Rh-ACS1, Rh-ACS2, Rh-ACS3 and Rh-ACO1 respectively. Northern blotting analysis revealed that, among three genes of ACS, ethylene-induced expression patterns of Rh-ACS3 gene corresponded to ACS activity and ethylene production in both cultivars. A more dramatic accumulation of Rh-ACS3 mRNA was induced by ethylene in ‘Kardinal’ than that of ‘Samantha’. As an ethylene action inhibitor, STS at concentration of 0.2 mmol/L generally inhibited the expression of Rh-ACSs and Rh-ACO in both cultivars, although it induced the expression of Rh-ACS3 transiently in ‘Kardinal’. Our results suggests that ‘Kardinal’ is more sensitive to ethylene than ‘Samantha’; and the changes of Rh-ACS3 expression caused by ethylene might be related to the acceleration of flower opening in ‘Samantha’ and the inhibition in ‘Kardinal’. Additional results indicated that three Rh-ACSs genes were differentially associated with flower opening and senescence as well as wounding.     

外源乙烯及1-MCP对牡丹CTR基因表达的影响

采用RT-PCR法研究外源乙烯和1-MCP对牡丹品种洛阳红(Paeonia suffruticosa Luoyanghong)1级切花CTR基因家族3个成员基因表达的影响,以揭示乙烯在牡丹采后开花和衰老进程中的调控机制.结果表明,在花朵开放和衰老进程中,PsCTR1和PsCTR2类似组成型表达,PsCTR3随内源乙烯的增加表达增强.PsCTR2和PsCTR3表达受外源乙烯的促进,PsCTR1的表达仅在花朵开放后期受到外源乙烯的促进.1-MCP处理增加了PsCTR1和PsCTR2的表达,但对PsCTR3的表达起先促进后抑制的作用.复合处理的结果表明,1-MCP处理可以逆转乙烯处理对PsCTR1和PsCTR2的作用;在切花进入盛花期和衰老期后,乙烯处理可以逆转1-MCP处理对PsCTR1、PsCTR2和PsCTR3的作用.     

Ethylene perception inhibitor 1-MCP decreases oxidative damage of leaves through enhanced antioxidant defense mechanisms in soybean plants grown under high temperature stress

Ethylene is a stress hormone involved in early senescence and abscission of vegetative and reproductive organs under stress conditions. Ethylene perception inhibitors can minimize the impact of ethylene-mediated stress. The effects of high temperature (HT) stress during flowering on ethylene production rate in leaf, flower and pod and the effects of ethylene inhibitor on ethylene production rate, oxidative damage and physiology of soybean are not understood. We hypothesize that HT stress induces ethylene production, which causes premature leaf senescence and flower and pod abscission, and that application of the ethylene perception inhibitor 1-Methyl cyclopropene (1-MCP) can minimize HT stress induced ethylene response in soybean. The objectives of this study were to (1) determine whether ethylene is produced in HT stress; (2) quantify the effects of HT stress and 1-MCP application on oxidative injury; and (3) evaluate the efficacy of 1-MCP at minimizing HT-stress-induced leaf senescence and flower abscission. Soybean plants were exposed to HT (38/28 °C) or optimum temperature (OT; 28/18 °C) for 14 d at flowering stage (R2). Plants at each temperature were treated with 1-MCP (1 μg L⁻¹) gas for 5 h or left untreated (control). High temperature stress increased rate of ethylene production in leaves, flowers and pods, production of reactive oxygen species (ROS), membrane damage, and total soluble carbohydrate content in leaves and decreased photosynthetic rate, sucrose content, F_v/F_m ratio and antioxidant enzyme activities compared with OT. Foliar spray of 1-MCP decreased rate of ethylene production and ROS and leaf senescence traits but enhanced antioxidant enzyme activities (e.g. superoxide dismutase and catalase). In conclusion, HT stress increased ethylene production rates, caused oxidative damage, decreased antioxidant enzyme activity, caused premature leaf senescence, increased flower abscission and decreased pod set percentage. Application of 1-MCP lowered ethylene and ROS production, enhanced antioxidant enzyme activity, increased membrane stability, delayed leaf senescence, decreased flower abscission and increased pod set percentage. The beneficial effects of 1-MCP were greater under HT stress compared to OT in terms of decreased ethylene production, decreased ROS production, increased antioxidant protection, decreased flower abscission and increased pod set percentage.     

Stamen abscission and water balance in Metrosideros flowers

Cymules (3-flowered units borne on single pedicels) were cut from inflorescences of Metrosideros collina J.R. & G. Forst. cv. Tahiti and used to test the effects of ethephon and ethylene on stamen abscission in the presence of silver thiosulphate (STS) and 1-methylcyclopropene (1-MCP), and to test the effects of holding solutions on cymule water balance and the progression of floral development. Flower bud and stamen abscission occurred in response to 0.5–5.0 and 0.1 μl l⁻¹ ethylene, respectively. Ethylene effects were partially negated by scrubbing exogenous ethylene, and more completely negated by STS (2.0 m M ). 1-MCP caused greater ethylene production and inhibited stamen abscission for only 1–2 days after treatment. Ethephon (10-10 000 mg l⁻¹) induced stamen wilting rather than abscission, an effect that was not negated by STS. Stamen wilting was negatively correlated with stamen relative water content, and the increase in stamen wilting was generally reduced by treatments that enhanced cymule mass. Stamen wilting was least using a 100 g l⁻¹ sucrose pulse or holding solutions containing 30–40 g l⁻¹ sucrose, with hydroxyquinoline citrate (200 mg l⁻¹) maintained at pH 5. Our results indicate that 1-MCP may be relatively ineffective in blocking the effects of ethylene on the abscission of organs, such as the stamens of M . collina , which are highly sensitive to this hormone.     

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.     

1-甲基环丙烯对百合采后切花某些生理指标的影响

百合切花经1-甲基环丙烯(1-MCP)处理后瓶插寿命延长,花朵发育和衰老进程延缓,乙烯峰出现时间推迟.经1-MCP处理的亚洲百合的乙烯峰值和细胞膜透性降低,而麝香百合可溶性蛋白质含量则不受影响.     

Comparison of the role of gibberellins and ethylene in response to submergence of two lowland rice cultivars, Senia and Bomba

We examined the gibberellin (GA) and ethylene regulation of submergence-induced elongation in seedlings of the submergence-tolerant lowland rice (Oryza sativa L.) cvs Senia and Bomba. Elongation was enhanced after germination to facilitate water escape and reach air. We found that submergence-induced elongation depends on GA because it was counteracted by paclobutrazol (an inhibitor of GA biosynthesis), an effect that was negated by GA₃. Moreover, in the cv Senia, submergence increased the content of active GA₁ and its immediate precursors (GA₅₃, GA₁₉ and GA₂₀) by enhancing expression of several GA biosynthesis genes (OsGA20ox1 and -2, and OsGA3ox2), but not by decreasing expression of several OsGA2ox (GA inactivating genes). Senia seedlings, in contrast to Bomba seedlings, did not elongate in response to ethylene or 1-aminocyclopropane-1-carboxylic-acid (ACC; an ethylene precursor) application, and submergence-induced elongation was not reduced in the presence of 1-methylcyclopropene (1-MCP; an ethylene perception inhibitor). Ethylene emanation was similar in Senia seedlings grown in air and in submerged-grown seedlings following de-submergence, while it increased in Bomba. The expression of ethylene biosynthesis genes (OsACS1, -2 and -3, and OsACO1) was not affected in Senia, but expression of OsACS5 was rapidly enhanced in Bomba upon submergence. Our results support the conclusion that submergence elongation enhancement of lowland rice is due to alteration of GA metabolism leading to an increase in active GA (GA₁) content. Interestingly, in the cv Senia, in contrast to cv Bomba, this was triggered through an ethylene-independent mechanism.     

Physiological Responses of Cut Rose Flowers to Exposure to Low Temperature: Changes in Membrane Permeability and Ethylene Production

Senescence of cut rose flowers (Rosa hybrida L. cv. Mercedes)at 22 °C occurred earlier in flowers previously held at2 °C for 10 d or 17 d than in freshly cut flowers. Thisadvanced senescence was observed as an earlier increase in bothethylene production rate and membrane permeability. The risein ethylene production preceded the rise in the level of ionleakage from petals, and this in turn preceded visible symptomsof petal death. Applied ethylene stimulated ion leakage andinhibitors of ethylene synthesis and action (amino-oxyaceticacid and silver thiosulphate respectively) inhibited the normalincrease in ion leakage. The maximum rate of ethylene productionof 22 °C increased markedly in petals of flowers previouslyheld at 2 °C, up to nine times the level in fresh flowers.We conclude that during exposure of rose flowers to 2 °C,in addition to senescence, processes were induced which ledto stimulated ethylene production after transferral to 22 °C.Ethylene apparently caused the subsequent advance in membranepermeability and senescence. Key words: Rose flower, Low temperature, Senescence     

Ethylene- and dark-induced flower abscission in potted Plectranthus: Sensitivity,prevention by 1-MCP,and expression of ethylene biosynthetic genes

Prevention of ethylene- and shipping-induced flower abscission is necessary to maintain the quality of both cut flowers and potted plants during handling, transport and retail display. The aims of the present work were to determine the sensitivity of Plectranthus cultivars to applied ethylene, to alleviate ethylene- and shipping-induced flower abscission in intact potted plants using 1-methylcyclopropene (1-MCP), and to investigate the possible causes of dark-induced flower abscission. All cultivars were sensitive to ethylene in a concentration-dependent manner, and complete abscission occurred within 24 h with 1 and 2 μl l^− 1 ethylene. Unopened buds were more sensitive to applied ethylene, and exhibited greater abscission than open flowers. Ethylene synthesis remained below detection limits at all time points under control and continuous dark conditions. Dark treatment significantly increased flower abscission in Plectranthus cultivars, and like ethylene-induced flower abscission, this could be prevented by continuous 1-MCP treatment. Gene expression of ethylene biosynthetic enzymes ACS and ACO was examined as possible causes for the accelerated flower abscission observed in plants kept in continuous darkness. Expression patterns of ACS and ACO varied between different cultivars of Plectranthus. In some cases, increased expression of ACS and ACO led to increased flower abscission. Gene expression was higher in open flowers when compared to unopened flowers suggesting a cause for the observed preferential shedding of open flowers in some cultivars. Although the cause of dark-induced abscission in Plectranthus remains elusive, it can be effectively controlled by treatment with 1-MCP.     

Ethylene and in vitro rooting of rose shoots

Effects of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), ethylene biosynthesis inhibitor, (CoCl₂), and inhibitor of ethylene binding to receptors, 1-methylcyclopropene (1-MCP), on ethylene production and rooting in shoot culture of Rosa hybrida L. cv. Alba meidiland were studied. Additionally, effect of ethylene removal by KMnO₄ and HgClO₄ on rooting was tested. ACC increased ethylene production and delayed root formation, decreased the number of roots per shoot and inhibited root growth. In contrast, inhibition of ethylene production by CoCl₂ accelerated root emergence, and increased the number of roots per shoot. Likewise, removing ethylene from the ambient atmosphere improved root emergence and, increased root number of per shoot and markedly inhibited root growth. Blocking the ethylene receptors by 1-MCP increased ethylene level in the ambient atmosphere and increased both emergence and root formation. Both ethylene biosynthesis and action are involved in the control of rooting. Ethylene concentration in glass jars was too high for root emergence and formation, but was appropriate for root growth. CoCl₂ or 1-MPC can be recommended for regulation of rooting in rose shoot culture, since both emergence and number of roots were improved but root growth was not inhibited.     

Inhibition of ethylene-induced cellular senescence symptoms by 1-methylcyclopropene, a new inhibitor of ethylene action

Ethylene is known to accelerate flower senescence, but the sequence of events that links its interaction with the tissue and the final senescence symptoms is still obscure. Recently, 1-methylcyclopropene (1-MCP) was found to inhibit ethylene-induced wilting in flowers. This work was carried out in order to investigate the effects of 1-MCP on cellular senescence symptoms in petunia flowers following expossure to ethylene. Cut petunia ( Petunia hybrida ) flowers that were exposed to ethylene for 12 h at concentrations of 1–12 ppm wilted sooner than their untreated counterparts. This effect was abolished by a 6-h pre-treatment with 1-MCP. Immediately following the ethylene treatment, decreases in petal fresh weight and total protein content were measured, along with higher electrolyte leakage, and lower membrane lipid fluidity and protein content. When applied alone, 1-MCP had relatively little impact on these parameters. However, when the flowers were treated with 1-MCP prior to the ethylene treatment, ethylene had no effect. These results indicate that while ethylenes effects on wilting were obvious 3 days after the treatment, cellular parameters were affected already at the end of the treatment. Since 1-MCP repressed these early ethylene effects, it was concluded that it interferes with ethylene action in petunia flowers at a rather early stage, long before apparent wilting.     

Changes in the Physical State of Membrane Lipids during Senescence of Rose Petals

Changes in the physical state of microsomal membrane lipids during senescence of rose flower petals (Rosa hyb. L. cv Mercedes) were measured by x-ray diffraction analysis. During senescence of cut flowers held at 22°C, lipid in the ordered, gel phase appeared in the otherwise disordered, liquid-crystalline phase lipids of the membranes. This was due to an increase in the phase transition temperature of the lipids. The proportion of gel phase in the membrane lipids of 2-day-old flowers was estimated as about 20% at 22°C. Ethylene may be responsible, at least in part, for the increase in lipid transition temperature during senescence since aminooxyacetic acid and silver thiosulfate inhibited the rise in transition temperature. When flowers were stored at 3°C for 10 to 17 days and then transferrd to 22°C, gel phase lipid appeared in membranes earlier than in freshly cut flowers. This advanced senescence was the result of aging at 3°C, indicated by increases in membrane lipid transition temperature and ethylene production rate during the time at 3°C. It is concluded that changes in the physical state of membrane lipids are an integral part of senescence of rose petals, that they are caused, at least in part, by ethylene action and that they are responsible, at least in part, for the increase in membrane permeability which precedes flower death.