Pollination-Induced Expression of Ethylene Biosynthetic Genes at Transcription Level in Orchid Flowers

The authors investigated pollination-induced ethylene production and expression patterns of genes encoding 1-aminocyclopropane-l-carboxylate (ACC) synthase and ACC oxidase in orchid flowers (Doritaenopsis hybrida Hort. ). Following pollination both ACC synthase and ACC oxidase mRNAs were detected in the different organs of flowers, and the patterns of both ACC synthase and ACC oxidase mRNA accumulation were similar, mRNA accumulation of ACC synthase mRNA was more organ-specific than that of ACC oxidase mRNA. However, ACC oxidase mRNAs were much more abundant than ACC synthase mRNAs in the flower organs.     

授粉诱导兰花花部乙烯生物合成基因在转录水平上的表达

朵丽蝶兰（Ｄｏｒｉｔａｅｎｏｐｓｉｓｈｙｂｒｉｄａ Ｈｏｒｔ．）的花授粉后,测定乙烯的产生,并分析授粉后花部各器官乙烯生物合成的ＡＣＣ合成酶和ＡＣＣ氧化酶两个基因转录水平上的表达。授粉后在花部均可探测到ＡＣＣ合成酶和ＡＣＣ氧化酶的ｍ ＲＮＡ。在花部不同器官之间,此两种酶的ｍ ＲＮＡ的积累水平均表现出一些差异。ＡＣＣ合成酶的ｍ ＲＮＡ 积累与ＡＣＣ氧化酶相比,具有更明显的特异性。而ＡＣＣ氧化酶ｍ ＲＮＡ 的积累水平远比ＡＣＣ合成酶高     

嫁接对网纹甜瓜果实乙烯生物合成及CmACO1基因表达的影响

以“新汉城翠蜜”网纹甜瓜为接穗,以“圣砧一号”南瓜为砧木进行嫁接,研究嫁接对目光温室网纹甜瓜果实乙烯生物合成及CmACO1基因转录水平表达的影响。结果表明：嫁接明显降低了网纹甜瓜果实ACC含量及乙烯释放量,在乙烯释放高峰时,嫁接的网纹甜瓜果实乙烯释放量比自根的降低了12．6％;嫁接降低了果实中ACC合成酶和ACC氧化酶活性,其最大值分别比自根网纹甜瓜降低了9．0％和6．8％;嫁接抑制了CmACO1的表达,其相对表达量最大值比自根网纹甜瓜降低了39．0％;嫁接网纹甜瓜果实中乙烯释放高峰、ACC合成酶和ACC氧化酶活性峰值及CmACO1相对表达量峰值出现的时间均比自根的延迟了3d。     

Recovery of ethylene biosynthesis in diazocyclopentadiene (DACP)-treated tomato fruit

Diazocyclopentadiene (DACP), a competitive ethylene action inhibitor binds irreversibly to the ethylene receptor to reduce tissue responses to ethylene. Tomato fruit (Lycopersicon esculentum Mill cv lsquo;Rondellorsquo;) were treated with DACP at the mature green stage. Ethylene biosynthesis and respiration rate were depressed. Color changes from green to red were delayed. Compared to the control, ACC content increased and ACC oxidase activity in vivo decreased in DACP-treated fruit. Thus, decrease of ethylene production caused by DACP treatment was due to the reduction of ACC oxidase activity. The decline in ripening subsequently recovered after DACP treatment. Results from the Northern analysis for gene expression of ACC synthase and ACC oxidase, showed that expression of both genes declined in DACP-treated fruit, and then recovered. Therefore the recovery of ethylene production was due to the recovery in gene expression and activity of ACC oxidase. We conclude that the effects of DACP on ethylene biosynthesis are on expression of ACC synthase and ACC oxidase genes, and/or regulation of ACC oxidase activity.     

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.     

Ethylene regulation of fruit ripening: Molecular aspects

Progress in ethylene regulating fruit ripening concerning itsperception and signal transduction and expression of ACC synthaseand ACC oxidase genes is reviewed. ACC synthase and ACC oxidasehave been characterized and their genes cloned from various fruittissues. Both ACC synthase and ACC oxidase are encoded bymultigene families, and their activities are associated withfruit ripening. In climacteric fruit, the transition toautocatalytic ethylene production appears to be due to a seriesof events in which ACC sythase and ACC oxidase genes have beenexpressed developmentally. Differential expression of ACCsynthase and ACC oxidase gene family members is probably involvedin such a transition that ultimately controls the onset of fruitripening.In comparison to ACC synthase and ACC oxidase, less is knownabout ethylene perception and signal transduction because of thedifficulties in isolating and purifying ethylene receptors orethylene-binding proteins using biochemical methods. However, theidentification of the Nr tomato ripening mutant as anethylene receptor, the applications of new potent anti-ethylenecompounds and the generation of transgenic fruits with reducedethylene production have provided evidence that ethylenereceptors regulate a defined set of genes which are expressedduring fruit ripening. The properties and functions of ethylenereceptors, such as ETR1, are being elucidated.Application of molecular genetics, in combination withbiochemical approaches, will enable us to better understand theindividual steps leading from ethylene perception and signaltransduction and expression of ACC synthase and ACC oxidase genefamily member to the physiological responses.     

Oxygen control of ethylene biosynthesis during seed development in Arabidopsis thaliana (L.) Heynh

An unforeseen side-effect on plant growth in reduced oxygen is the loss of seed production at concentrations around 25% atmospheric (50 mmol mol-1 O2). In this study, the model plant Arabidopsis thaliana (L.) Heynh. cv. 'Columbia' was used to investigate the effect of low oxygen on ethylene biosynthesis during seed development. Plants were grown in a range of oxygen concentrations (210 [equal to ambient], 160, 100, 50 and 25 mmol mol-1) with 0.35 mmol mol-1 CO2 in N2. Ethylene in full-sized siliques was sampled using gas chromatography, and viable seed production was determined at maturity. Molecular analysis of ethylene biosynthesis was accomplished using cDNAs encoding 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase in ribonuclease protection assays and in situ hybridizations. No ethylene was detected in siliques from plants grown at 50 and 25 mmol mol-1 O2. At the same time, silique ACC oxidase mRNA increased three-fold comparing plants grown under the lowest oxygen with ambient controls, whereas ACC synthase mRNA was unaffected. As O2 decreased, tissue-specific patterning of ACC oxidase and ACC synthase gene expression shifted from the embryo to the silique wall. These data demonstrate how low O2 modulates the activity and expression of the ethylene biosynthetic pathway during seed development in Arabidopsis.     

伤处理和乙烯对桃ACC氧化酶基因表达的影响

桃果实不耐贮运,特别是溶质水蜜桃、珐I大11＿程技术的发展使番茄果实实现延熟保鲜'－'、人f［］也试图通过乙烯合成的关键酶的］i义HNA技术来延长桃果实的贮运期。：ICC氧化酶是乙烯生物合成的关键酶之一,ACC氧化酶4peJL从番茄'、矮牵牛。。。桃卜'、苹果、'等许多植物...     

Ethylene biosynthesis in a chilling-sensitive<Emphasis Type="Italic">Arabidopsis</Emphasis> mutant,<Emphasis Type="Italic">chs4-2</Emphasis>

We investigated chilling-induced changes in ethylene levels in Arabidopsis to find plants with distinct patterns of ethylene production in the cold-related biosynthetic pathway. The sensitive mutants identified here includedchs1-2,chs4-2, andchs6-2. Among these, plants of thechs4-2 mutant produced more ethylene than did the wild type after both were transferred from 4°C or 10°C to 22°C. This mutant also showed less freezing tolerance and more electrolyte leakage than the wild-type plants. Our results suggest a relationship between ethylene biosynthesis and chilling sensitivity in the mutant To determine which of the enzymes involved in ethylene biosynthesis were induced by chilling, we tested the activities of ACC synthase and ACC oxidase in both mutant and wild-type plants, and found greater activity by ACC synthase as well as a higher ACC content in the mutants after all the plants were transferred from 10°C to 22°C. However, ACC oxidase activity did not differ between mutant and wild-type plants in response to chilling treatment Therefore, we conclude thatchs4-2 mutants produce more ethylene than do other mutants or the wild type during their recovery from chilling conditions. Furthermore, we believe that ACC synthase is the key enzyme involved in this response.     

Inhibition of ethylene biosynthesis by antisense ACC oxidase RNA prevents chilling injury in Charentais cantaloupe melons

Non-freezing low temperature storage causes injury to melons and most other fruit and vegetables of tropical and subtropical origin. We demonstrate here that ethylene suppression through an antisense ACC oxidase (ACO) gene considerably reduced the sensitivity of Charentais cantaloupe melons to chilling injury. In contrast to wild-type fruit, antisense ACO melons did not develop the characteristic chilling injury of pitting and browning of the rind neither when stored at low temperature (3 weeks at 2 °C) nor upon rewarming. Treating antisense melons with 10 p.p.m. ethylene for more than 1 d prior to cold storage resulted in the restoration of chilling sensitivity. When the ethylene treatment was performed after cold storage, the chilling injury symptoms did not appear. The tolerance to chilling was associated with a lower accumulation of ethanol and acetaldehyde, reduced membrane deterioration and higher capacity of the fruit to remove active oxygen species. The activities of catalase, superoxide dismutase and peroxidase were markedly increased in antisense ACO fruit in comparison with wild-type fruit, particulary upon rewarming and post-storage ethylene treatment. Severe chilling injury symptoms were correlated with a lower activity of activated oxygen scavenging enzymes. These results demonstrate that ethylene acts in conjunction with low temperature to induce metabolic shifts that participate in the development of chilling injury.     

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…     

桃ACC合酶基因的分离及其差异表达

利用5′/3′RACE PCR技术,从桃(Prunus persica (L.) Batsch)果实中克隆了植物乙烯生物合成的关键酶--ACC合酶的全长cDNA pacs,对pacs基因进行全序列测定表明,该基因全长1 848个碱基,编码区为1 449个碱基,5′端有177个碱基的非编码区序列,3′端有219个碱基的非编码区序列(不包括终止密码子TAA).pacs基因编码区共编码483个氨基酸,蛋白质大小为54 kD,等电点为6.43.pacs与番茄(S19677)、梅(AB031026)、番木瓜(U68216)、苹果(AB034993)等其他植物ACC合酶cDNA氨基酸序列同源性分别为65%、70%、75%、90%,并存在与这些ACC合酶氨基酸的活性位点保守序列SLSKDMGFPGFR.RT-PCR结合杂交分析表明,pacs和我们以前克隆的桃ACC合酶cDNA pacs12(AF467782)在叶片和花中基因表达模式基本一致,伤处理和IAA均能诱导叶片pacs 和pacs12基因的表达,但pacs在伤处理叶片的表达水平比pacs12高;pacs 和pacs12基因在果实表达有所不同,pacs在绿熟和成熟果实中均有表达,而pacs12在绿熟果实中基本检测不到,在成熟果实中才有表达,两者在果实中的表达水平比伤处理和IAA处理叶片和花中要低.