1-甲基环丙烯采后处理对樱桃番茄果实成熟过程的影响

研究了不同浓度(0、0.035、0.07和0.11μL/L)的乙烯受体竞争性抑制剂1-甲基环丙烯(1-MCP)采后处理对绿熟期樱桃番茄的乙烯合成、果实软化、果实色素(叶绿素、茄红素、β-胡萝卜素)含量消长的影响.0.07 μL/L及其以上浓度的1-MCP降低了前期乙烯合成,同时推迟了乙烯释放高峰,但0.035 μL/L浓度的1-MCP处理并不能抑制内源乙烯合成.1-MCP显著延迟了果实软化和叶绿素降解,但并不影响这两个过程的启动.茄红素合成的启动和积累均受到了1-MCP抑制,而1-MCP并不推迟β-胡萝卜素合成的启动,只抑制其积累.这些结果提示了乙烯调节成熟生理过程的不同机制.对于绿熟期的樱桃番茄,0.07～0.11μL/L的1-MCP是实用的有效处理浓度.1-MCP有效浓度可能用于了解果实的乙烯受体水平和乙烯敏感性.     

Responses of strawberry fruit to 1-Methylcyclopropene (1-MCP) and ethylene

1-Methylcyclopropene (1-MCP), a competitive inhibitorof ethylene action, binds to the ethylene receptor toregulate tissue responses to ethylene. In this work,we investigated the effects of 1-MCP and exogenousethylene on ripening, respiration rate, ionicconductivity and peroxidase activity in strawberryfruit. Strawberry fruit can ripen without exogenousethylene treatment, but exogenous ethylene inducessecondary ripening processes. Results indicated thatstimulation of respiration by ethylene wasdose-dependent. Fruit colour development and softeningwere slightly accelerated by ethylene, but changes insoluble solid content were not. 1-MCP may/may notaffect the respiratory rise induced by exogenousethylene dependent on fruit maturity. Cycloheximide(CHI) reduced the ethylene-induced respiratoryincrease. Combinations of 1-MCP and CHI reducedrespiration more than CHI alone. 1-MCP and CHI did notinfluence the primary respiratory change in nonethylene-treated fruit. This indicates that ethyleneinduced respiratory increase may involve an ethylenereceptor in early harvested fruit, but not in laterharvested fruit. Exogenous ethylene stimulatedrespiration by regulating new respiratory enzyme(s)synthesis in strawberry fruit. Ethylene induced anionic leakage increase, and this was positivelycorrelated to fruit water loss and peroxidaseactivity. These results suggest that non-climactericfruit, such as strawberry, may have different ethylenereceptor(s) and/or ethylene receptor(s) may havedifferent regulatory functions. It may be thesecondary effect of ethylene to stimulate respirationin strawberry. Non-climacteric fruit ripening may berelated to the development of active oxygen species(AOS) induced by postharvest stress.     

1-Methylcyclopropene prevents cotton physiological and molecular responses to ethylene

The phytohormone ethylene can cause adverse effects in plants, including inhibition of shoot elongation and abscission of leaves, flowers and fruits. 1-Methylcyclopropene (1-MCP) is a competitive inhibitor of ethylene binding with the ethylene receptors and prevents ethylene responses. To determine the effectiveness of 1-MCP as an ethylene prophylactic for cotton, an assay system was developed that integrated analyses of leaf declination, shoot elongation and ethylene-responsive gene expression (GhACS6, GhACO5, GhEIN4, GhLTL1). Using a flow-through controlled growth system, the optimal parameters of ethylene treatment in eliciting responses and of 1-MCP treatment in preventing these responses, were determined. Shoot elongation and gene expression changes in response to ethylene correlated well, but gene expression changes were found to offer a more robust estimate of ethylene responsiveness. The effect of ethylene treatment on the expression of the marker genes was determined to be optimal with 3?h of 10???L?L^?1 fumigation. 250?nL?L^?1 of gaseous 1-MCP provided for 1?h immediately before ethylene fumigation was highly efficacious at preventing ethylene responses, but the duration of protection did not exceed 48?h. A liquid formulation of 1-MCP designed for field use was found to be equally effective as the gas. The results, and the system described, may prove useful in increasing 1-MCP efficacy as a tool to manage the negative effects of stress ethylene in cotton crops.     

Responses of banana fruit to treatment with 1-methylcyclopropene

Experiments were conducted to determine levels of 1-methylcyclopropene (1-MCP) exposure needed to prevent ethylene-stimulated banana fruit ripening, characterise responses of ethylene-treated fruit to subsequent treatment with 1-MCP, and to test effects of subsequent ethylene treatment on 1-MCP-treated fruit softening. Fruit softening was measured at 20°C and 90% relative humidity. One hour exposure at 20°C to 1000 nl 1-MCP/l essentially eliminated ethylene-stimulated ripening effects. Exposure for 12 h at 20°C to just 50 nl 1-MCP/l was similarly effective. Fruit ripening initiated by ethylene treatment could also be delayed with subsequent 1-MCP treatment. However, 1-MCP treatment only slowed down ripening of ethylene-treated fruit when applied at 1 day after ethylene and was ineffective when applied 3 or 5 days after ethylene treatment. The ripening response of fruit treated with 1-MCP and subsequently treated with ethylene varied with interval time between 1-MCP and ethylene treatments. As time increased, the response of 1-MCP-treated fruit to ethylene was enhanced. Responses to 0.1, 1, 10 or 100 µl ethylene/l concentrations were similar. Enzyme kinetic analysis applied to 1-MCP effects on ethylene-induced softening of banana fruit suggested that 1-MCP inhibition is by noncompetitive antagonism of ethylene binding.     

The use of 1-methylcyclopropene (1-MCP) on fruits and vegetables

The recent availability of the inhibitor of ethylene perception, 1-methylcyclopropene (1-MCP), has resulted in an explosion of research on its effects on fruits and vegetables, both as a tool to further investigate the role of ethylene in ripening and senescence, and as a commercial technology to improve maintenance of product quality. The commercialization of 1-MCP was followed by rapid adoption by many apple industries around the world, and strengths and weaknesses of the new technology have been identified. However, use of 1-MCP remains limited for other products, and therefore it is still necessary to speculate on its commercial potential for most fruits and vegetables. In this review, the effects of 1-MCP on fruits and vegetables are considered from two aspects. First, a selected number of fruit (apple, avocado, banana, pear, peaches and nectarines, plums and tomato) are used to illustrate the range of responses to 1-MCP, and indicate possible benefits and limitations for commercialization of 1-MCP-based technology. Second, an outline of general physiological and biochemical responses of fruits and vegetables to the chemical is provided to illustrate the potential for use of 1-MCP to better understand the role of ethylene in ripening and senescence processes.     

1-MCP对东方百合开放与衰老的影响

以东方系列百合（Lilium spp.）‘西伯利亚’品种为材料,研究了1-甲基环丙烯（1-MCP）对百合切花质膜透性、乙烯释放量、丙二醛含量、可溶性蛋白质含量等生理指标的影响。结果表明：1-MCP可延缓百合切花花瓣质膜相对透性的增加,延长百合切花瓶插寿命;降低百合花瓣乙烯释放量,推迟乙烯峰的出现;降低百合花瓣丙二醛含量,对可溶性蛋白含量的变化无明显影响。本研究结果说明1-MCP对东方百合切花的保鲜有一定效果,确定了1-MCP处理东方百合的最佳使用浓度为0.01μL/L。     

Ethylene-induced stomatal closure in Arabidopsis occurs via AtrbohF-mediated hydrogen peroxide synthesis

Ethylene is a plant hormone that regulates many aspects of growth and development. Despite the well-known association between ethylene and stress signalling, its effects on stomatal movements are largely unexplored. Here, genetic and physiological data are provided that position ethylene into the Arabidopsis guard cell signalling network, and demonstrate a functional link between ethylene and hydrogen peroxide (H(2)O(2)). In wild-type leaves, ethylene induces stomatal closure that is dependent on H(2)O(2) production in guard cells, generated by the nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase AtrbohF. Ethylene-induced closure is inhibited by the ethylene antagonists 1-MCP and silver. The ethylene receptor mutants etr1-1 and etr1-3 are insensitive to ethylene in terms of stomatal closure and H(2)O(2) production. Stomata of the ethylene signalling ein2-1 and arr2 mutants do not close in response to either ethylene or H(2)O(2) but do generate H(2)O(2) following ethylene challenge. Thus, the data indicate that ethylene and H(2)O(2) signalling in guard cells are mediated by ETR1 via EIN2 and ARR2-dependent pathway(s), and identify AtrbohF as a key mediator of stomatal responses to ethylene.     

Effect of 1-methylcyclopropene on ethylene-induced abscission in citrus

Pre-treatment of citrus leaves and leaf explants ( Citrus sinensis [L.] Osbeck cv. Shamouti), with 1-methylcyclopropene (1-MCP), induced endogenous ethylene production when leaves were further incubated in air. The induction of ethylene production was 1-MCP concentration-dependent. Abscission was concomitantly delayed. In leaves pre-treated with 1-MCP followed by exposure to ethylene, abscission was significantly delayed in comparison with those without 1-MCP pre-treatment. When leaf explants were co-treated for 24 h with ethylene and 1-MCP, abscission was delayed quite efficiently. The Lineweaver-Burke plot yielded a half-maximal value of 0.234 μl l⁻¹ for the effect of ethylene on abscission. 1-MCP⁻¹ competed kinetically with ethylene with a K_i value of approximately 1.4−5.5 nl l⁻¹ 1-MCP. Under these experimental conditions there was some competition between 1-MCP and ethylene. However, ethylene was not able to completely counteract the inhibitory effect of 1-MCP. Pre-treatment with 1-MCP, followed by exogenous ethylene treatment, suppressed the induction of endo- β -glucanase (EG) activity at the laminar abscission zone. The ethylene-dependent accumulation of the hydrolyse gene was demonstrated by blocking the accumulation of CsCel a1 mRNA by 1-MCP. Six hours of exposure of leaves to 1-MCP at various times during a total of 24 h ethylene treatment efficiently reversed ethylene induction of CsCel a1 gene at mRNA level up to 18 h. The results demonstrate that the induction of abscission by ethylene is controlled at mRNA level at the abscission zone.     

Differential Suppression of Ethylene Biosynthesis and Receptor Genes in ‘Golden Delicious’ Apple by Preharvest and Postharvest 1-MCP Treatments

Harvista?, a sprayable formulation of 1-methylcyclopropene (1-MCP), has recently been developed for preharvest use on horticultural products, whereas SmartFresh? is a widely used 1-MCP treatment for products after harvest. The effects of Harvista? on apple fruit ripening when sprayed at different maturities and on expression patterns of ethylene biosynthesis and receptor genes during storage have been investigated. Harvista? applied to on-tree maturing apple fruit at an average starch pattern index of 2.5 resulted in a higher at-harvest firmness value compared with those treated at a starch pattern index of 1.5 and 3.5. This indicates that the timing of the Harvista? application is critical. An application of Harvista? led to better postharvest fruit firmness retention as well as reduced ethylene production. In addition, both preharvest and postharvest 1-MCP treatments resulted in contrasting responses in the expression patterns of two ethylene biosynthesis genes and in differentially suppressing effects on four ethylene receptor genes. Furthermore, the combined application of Harvista? + SmartFresh? resulted in greater fruit firmness retention and longer ethylene suppression. The expression profiles of these genes during on-tree fruit maturation prior to Harvista? application were also characterized. Different regulation patterns of receptor genes could contribute to differential effects by 1-MCP treatments. The potential roles of Harvista? to manipulate the ripening process as well as the molecular mechanism influencing 1-MCP treatment efficacy are discussed.     

Assessment of the potency of 1-substituted cyclopropenes to counteract ethylene-induced processes in plants

A study was undertaken to assess the potency of 1-methylcyclopropene (1-MCP) analogues to block the ethylene receptor and thereby inhibit ethylene action. Eight structural analogues of 1-MCP with substitution in the 1-position and a side chain containing 2–10 carbons were synthesized and their potency to inhibit ethylene-induced plant processes was tested on climacteric fruit like avocado, and tomato, on ethylene-induced growth modification in etiolated pea seedlings and on abscission in citrus leaf explants. High concentrations of ethylene were used under conditions which hasten ethylene-induced processes. The results showed differences in the responses of the various tissues tested as related to the concentrations of the inhibitors. Some required much higher concentration to exert the same effect, while some, when applied at the same concentration, blocked the receptor for a longer period of time than the others. Fruits responded differently than other plant organs to the same inhibitor, indicating possible differences in characteristics and availability of the ethylene receptors in the various tissues. The potency of the inhibitors was greatly affected by their molecular structure and size. The highest potency of a given inhibitor was obtained when the treatment was applied before the onset of ethylene action. The relationship between ethylene and the inhibitors was found to be of an apparent non-competitive nature. All the fruits treated with the various inhibitors resumed normal ripening after recovery from the inhibition which is crucial when considering the putative inhibitors for practical use.     

Auxin abolishes inhibitory effects of methylcyclopropen and amino oxyacetic acid on pollen grain germination,pollen tube growth,and the synthesis of ACC in petunia

As established by us earlier, ethylene behaves as a regulator of germination, development, and growth of male gametophyte during the progamic phase of fertilization. However, the mechanisms of the regulation of these processes remain so far unstudied. It is believed that the main factor providing variety of the ethylene responses is its interaction with other phytohormones. According to our working hypothesis, ethylene controls germination of pollen grains (PGs) and growth of pollen tubes (PTs) by interacting with auxin, which, as the available data indicate, is likely a key regulator of plant cell polarization and morphogenesis and one of the factors modulating the biosynthesis of ethylene at the level of ACC-synthase gene expression. In the present work, on germinating in vitro male gametophyte and the pollen-stigma system for petunia (Petunia hybrida L.) effects of phytohormones (ethylene and IAA) and known blockers repressing ethylene reception (1-methylcyclopropene, 1-MCP), the synthesis of ACC (amino oxyacetic acid, AOA) and transport IAA (triyodbenzoynaya acid, TYBA) on PGs germination, PTs growth and the synthesis of ACC were investigated. According to the data obtained, exogenous ethylene and IAA stimulated both PGs germination and PTs growth. 1-MCP and TYBA completely inhibited the first process, whereas IAA abolished the inhibitory action of 1-MCP and AOA on both the above processes. Etrel only partially weakened the inhibitory effect of TYBA. Examination of ACC synthesis modulation with AOA showed that IAA does not affect the level of ACC in germinating in vitro male gametophyte and nonpollinated stigmas, while this phytohormone insignificantly raised the level of ACC and abolished the inhibitory effect of AOA on its synthesis in the pollenstigma system. Pollination of stigmas with the pollen preliminarily treated with 1-MCP led to 2.5-fold decline in both the rate of PT growth and the level of ACC. At the same time, IAA abolished the inhibitory action of 1-MCP recovering the synthesis of ACC and growth of PTs to the control values. All these results, taken together, provide evidence for the interaction of the signal transduction pathways of ethylene and auxin at the level of ACC biosynthesis in the course of germination and growth of petunia male gametophyte during the progamic phase of fertilization.     

Ethylene is required for both the initiation and progression of softening in pear (Pyrus communis L.) fruit

In order to investigate the physiological role of ethylene in the initiation and subsequent progression of softening, pear fruit were treated with propylene, an analogue of ethylene or 1-methylcyclopropene (1-MCP), a gaseous inhibitor of ethylene action at the preclimacteric or ripening stages. The propylene treatment at the pre-ripe stage stimulated ethylene production and flesh softening while the 1-MCP treatment at the same stage markedly retarded the initiation of the ripening-related events. Moreover, 1-MCP treatment after the initiation of ripening markedly suppressed the subsequent flesh softening and ethylene production. These results clearly indicate that ethylene is not merely a by-product, but plays a crucial role in both the initiation and maintenance of regulating the softening process during ripening. The observations also suggest that ethylene in ripening is regulated entirely in an autocatalytic manner. The mRNA accumulation of pear polygalacturonases (PG) genes, PC-PG1 and PC-PG2, was in parallel with the pattern of fruit softening in both propylene and 1-MCP treatments. However, the expression pattern of pear endo-1,4-beta-D-glucanases (EGase) genes, PC-EG1 and PC-EG2, was not affected in both treatments. The results suggest that ethylene is required for PGs expression even in the late ripening stage, but not for EGases.     

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.     

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.     

Herbivore-induced jasmonic acid bursts in leaves of Nicotiana attenuata mediate short-term reductions in root growth

Root growth in Nicotiana attenuata is transiently reduced after application of oral secretions (OS) of Manduca sexta larvae to wounds in leaves. Feeding of M. sexta or OS elicitation is known to result in jasmonic acid (JA) and ethylene bursts, and activates a suite of defence responses. Because both plant hormones are known to strongly reduce root growth, their activation might account for the observed reduction of root growth following herbivory. To test this hypothesis, we measured primary root growth with digital image sequence processing at high temporal resolution in antisense- lipoxygenase 3 (as LOX3 ) and inverted repeat- coronatin-insensitive 1 (ir COI1 ) seedlings which are impaired in JA biosynthesis and perception, respectively, and wild-type (WT) seedlings. Higher root growth rates in ir COI1 compared with WT were observed after OS elicitation. The dynamics of wound-induced root growth reduction coincide with the dynamics of root growth reduction induced by external application of methyl JA. In an experiment with 1-methylcyclopropen (1-MCP), a potent ethylene receptor blocker, no wounding-specific difference between growth of 1-MCP-treated plants and non-treated plants was observed, suggesting that wound-induced endogenous JA and not ethylene mediates the wounding-specific reduction in root growth. Yet, inhibiting the ethylene response by applying 1-MCP led to markedly increased root growth compared with that of control plants, indicating that ethylene normally suppresses plant growth in N. attenuata seedlings.     

Effects of 1-MCP on the vase life and ethylene response of cut flowers

Pretreatment for 6 h with low concentrations of 1-MCP (1-Methylcyclopropene, formerly designated as SIS-X), a cyclic ethylene analog, inhibits the normal wilting response of cut carnations exposed continuously to 0.4 μl·l^?1 ethylene. The response to 1-MCP was a function of treatment concentration and time. Treatment with 1-MCP was as effective in inhibiting ethylene effects as treatment with the anionic silver thiosulfate complex (STS), the standard commercial treatment. Other ethylene-sensitive cut flowers responded similarly to carnations. In the presence of 1 μl·l^?1 ethylene, the vase life of 1-MCP-treated flowers was up to 4 times that of the controls.     

乙烯诱导西瓜果实的水渍化败坏

为了研究乙烯在西瓜(Citrullus lanatusThunb.Mansfeld)果实水渍化败坏过程中的作用,先将果实在5μL/L 1-甲基环丙烯(1-MCP)气体中处理18 h,然后在50 μL/L乙烯和20℃温度下贮藏.西瓜果实对乙烯处理的最初反应表现为胎座组织的电导率和游离汁液增加,同时出现组织软化和水渍化.水渍化的症状最初在靠近花萼端的内果皮中发生,在乙烯处理的第2天开始出现,ACC合成酶(ACS)和ACC氧化酶(ACO)的活性明显提高.1-MCP单独处理不产生任何明显的作用,但是会完全抑制外源乙烯诱导的水渍化败坏.没有经过乙烯处理的西瓜果实,贮藏2 d以后出现呼吸强度和乙烯释放量的高峰,10 d以后水渍化现象也零星出现.这些结果和1-MCP的预防效果说明,西瓜果实的水渍化败坏是一种由乙烯诱导的衰老现象.