Analysis of ethylene receptor genes from petunia and arabidopsis

Chapter Literature Review 1.1 Biosynthesis, perception and signal transduction of ethylene The simple gaseous hormone ethylene plays an important role in many aspects of plant growth and development. It elicits diverse morphological changes of plant organs, including seed germination, leaf and flower senescence and fruit ripening. It is also involved in the process of responding to stress and pathogen attack (Abeles et al., 1992). Ethylene production during plant development is tightly regulated by internal signals. Higher level of ethylene production can be observed in plants that are subjected to environmental stresses such as wounding, pathogen attack, flooding or freezing. The induced ethylene in turn can elicit defense responses such as accelerated senescence, abscission of infected organs, and the induction of specific defense proteins (Chang and Shockey, 1999). The current understanding of ethylene biosynthesis as well as its perception and signal transduction pathway has been enhanced by isolation of mutants that have defective ethylene responses. Many dark-grown dicotyledonous seedlings in the presence of ethylene or after treatment with the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), exhibit a phenotype collectively called “triple response” (Goeschl et al., 1966; Taylor et al., 1988; Guzman and Ecker, 1990). Triple response refers to the morphological changes of the seedlings including short and thick hypocotyls, short roots and exaggerated apical hooks (Figure 1.1). The ethylene response mutants fall into two classes: a) ethylene-insensitive mutants and b) constitutive triple response mutants. Ethylene-insensitive mutants are those that fail to generate the triple response when treated with ethylene or exhibit only a weak response. These mutants include etr1 (for ethylene response), etr2, and ein-type (for ethylene insensitive) (Bleecker et al., 1988; Sakai et al., 1998; Roman et al., 1995; Chao et al.,1997). The constitutive triple response mutants, including ctr1 (for constitutive triple response), and eto2 (for ethylene overproducer), exhibit the triple response even in the absence of added ethylene (Kieber et al., 1993; Vogel et al., 1998). The two classes of mutants behave differently upon treatment with inhibitors of either ethylene synthesis or perception, including silver thiosulfate and aminoethoxyvinyl glycine (AVG). The mutants in the ctr1 category are unaffected by the ethylene inhibitors, they constitutively exhibit the triple response. Whereas the phenotype of the eto2 category mutants will revert to normal morphology if treated with ethylene inhibitors. This demonstrates that these mutants are defective in ethylene biosynthesis regulation and this defect can be overcome by providing exogenous ethylene inhibitors. (d) (c) (e) (b) (a) Figure 1.1. Effects of ethylene in plant development (from Johnson and Ecker, 1998). a) Wild-type Arabidopsis seedlings treated with ethylene show “triple response”, which refers to the phenotype including short and thick hypocotyls, short roots and exaggerated apical hooks. b) Tomato plants defective in ethylene perception are more prone to necrosis following pathogen infection. c) Root hair formed in nearly all the epidermal cells upon ethylene treatment. d) Ethylene promotes flower senescence and fruit ripening. e) Ethylene inhibits cell expansion in wild-type Arabidopsis plants. 1.1.1 Ethylene biosynthesis 1.1.1.1 Mechanistic overview of ethylene biosynthesis The ethylene biosynthetic pathway has been studied extensively since the establishment of S-adenosyl methionine (SAM) and 1-aminocyclopropane-1-carboxylic acid (ACC) as the precursors of ethylene (Yang and Hoffman, 1984). Based on this knowledge, two key enzymes, ACC synthase and ACC oxidase that catalyze the final two-step reaction from SAM to ACC and ACC to ethylene were successfully cloned from zucchini and tomato, respectively (Sato and Theologis, 1989; Hamilton et al., 1991). Thereafter, cloning and characterization of genes encoding these two enzymes has been carried out in many species such as Arabidopsis (Abel et al., 1995; Kieber et al., 1993), tomato (Terai, 1993; English et al., 1995), carnation (Woodson et al., 1992). These studies demonstrated that these two enzymes are encoded by a multigene family and expressed tissue-specifically and differently in response to developmental, environmental and hormone factors (Kende and Zeevaal, 1997). Detailed studies of these enzymes also led to further understanding of molecular regulation of ethylene production (Kende, 1993). SAM is the major methyl donor in plants and plays a role in methylation reactions including modifying lipids, proteins and nucleic acids. It is involved in many biochemical pathways, such as polyamine biosynthesis, and is the precursor of ethylene (Ravanel et al., 1998). The conversion from SAM to ACC by ACC synthase was considered to be a ratelimiting step since the ACC synthase enzyme has been shown to rise proportionally to ethylene levels within the tissues of some plants (Abeles et al., 1992) (Figure 1.2). ACC synthase also produces 5'-methylthioadenosine in addition to ACC, which is utilized for the synthesis of new methionine via a modified methionine cycle (Bleecker and Kende, 2000). This salvage pathway preserves the methyl group for another cycle of ethylene evolution. Continuously high rates of ethylene biosynthesis can therefore be maintained without demanding large amounts of free methionine. Finally, ACC is oxidized by ACC oxidase to synthesize ethylene, or it can be conjugated to a malonyl or glutamyl group to restrict its availability for ethylene production. Both ACC synthase and ACC oxidase are involved in the positive feedback regulation of ethylene biosynthesis. In this positive feedback, ethylene treatment leads to increased ethylene production in several plant species (Nakatsuka et al., 1998; Barry et al., 2000). 1.1.1.2 Regulation of ACC synthase and oxidase genes The transcription of different forms of ACC synthase is induced under different environmental or physiological conditions (Theologis, 1992). The members of ACC synthase (ACS) in Arabidopsis clearly exemplify this point that different isoforms are differently regulated. For example, ACS4 is induced in seedlings by wounding, cycloheximide and indoleacetic acid (Liang et al., 1992; Abel et al., 1995). ACS6 can be induced specifically by exposure to ozone in light-grown leaves and mechanical stress by touching (Vahala et al., 1998; Arteca and Arteca, 1999). Besides the regulation mentioned above, ACC synthase may also be post-translationally regulated as demonstrated by the eto2 mutant study (Vogel et al., 1998). In the ethylene overexpression mutant eto2, a single-base insertion caused an alteration of 12 residues of ACS5. Although the mRNA level of ACS5 changed little, ethylene production was nearly 20-fold of that in the wild type. Furthermore, cytokinin could increase ethylene production without induction of ACS5 mRNA, suggesting that the regulation of ethylene synthesis by cytokinin may be through posttranslational modification of ACC synthase. The most obvious evidence of posttranslational regulation is shown in tomato ACC synthase (Spanu et al., 1994). Its activity in cell culture can be induced by fungal elicitors, while addition of the protein kinase inhibitor staurosporine can rapidly inactivate this enzyme. While control of ethylene production may be largely attributed to ACC synthase, the periods of ACC oxidase induction also correlate with some events of senescence and wounding, which are ethylene-regulated (Callahan et al., 1992; Pogson et al., 1995). ACC oxidase protein is also thought to be post-translationally modified, giving rise to different isoforms (Stearns and Glick, 2003). Several isoforms of ACC oxidase have been identified which are active under different physiological conditions (Arshad et al., 2002). The conversion of ACC to ethylene in most tissues occurs at very low levels, suggesting that ethylene synthesis is tightly controlled. Expression of ACC oxidase can also be induced either by hormone or environmental stimuli except in fruits. Thus, defining the ratelimiting step in ethylene biosynthesis may differ in different plants, tissues and in response to environmental cues. 1.1.2 Ethylene perception and signal transduction Burg proposed that ethylene exerts its physiological action through a receptor, and a metal may be involved in the ethylene binding process (Burg and Burg, 1967). But attempts to isolate ethylene receptor by biochemical approaches failed. Elucidation of the mechanism of ethylene perception and signal transduction pathway began with the molecular and genetic studies on Arabidopsis in the last decade. Screening for mutants that have altered triple response allowed identification of many loci involved in the ethylene-signaling pathway. Cloning and characterization of the corresponding genes tentatively defined their order of action within the signal transduction pathway. 1.1.2.1 Ethylene perception and the action of ethylene receptor(s) As shown in Figure1.2, ethylene is perceived by plants through a family of integral membrane receptors. These receptors are homologous to “two-component” regulators initially characterized in bacteria (Stock et al., 1985). A typical two-component regulator consists of two types of signal transducers, a sensor component and a response regulator component (Stock et al., 1990; Parkinson, 1993). The N-terminal region of the sensor kinase monitors an environmental stimulus, and transfers the signal to its transmitter domain at the C-terminal which is a conserved histidine protein kinase (Parkinson and Kofoid, 1992). The histidine residue in the transmitter domain is then autophosphorylated and this phosphate group is acquired by a conserved residue in the receiver domain of the EBF1/2 Figure 1.2. The circuit of ethylene response from biosynthesis to perception and signal transduction to final gene induction (modified from Johnson and Ecker, 1998). a) The final two-steps in ethylene biosynthesis include converting ACC to ethylene by ACC synthase and ACC oxidase. b) Ethylene binds to the receptors on the membranes and inactives the downstream negative regulator CTR1 which probably functions as a MAPKKK in a MAPK cascade. c) Further transduction of ethylene signal requires positive regulators EIN2, EIN3, EIN5, and EIN6. d) The immediate target of EIN3 is ethylene response element binding proteins (EREBPs), which will induce specific subsets of ethylene response genes leading to different phenotypes upon receiving the stimuli. Two F box proteins, EBF1 and EBF2 interact and degrade EIN3 in the absence of ethylene. response regulator. Through the output domain of the regulator, expression of downstream target genes and ultimately cell behavior will be modified. These two-component regulators are predominantly sensors and signal transducers of many environmental stimuli in the adaptive responses of numerous prokaryotic species (Parkinson and Kofoid, 1992). Eukaryotes also have two-component signal transducers (Chang and Meyerowitz, 1994). In the yeast Saccharomyces cerevisiae, these genes were found to be involved in osmosensing MAP kinase cascade regulation (Maeda et al., 1994; Posas et al., 1996). In the fungus Neurospora, Nik1 plays a role in the hyphal growth process (Alex et al., 1996). Studies on the slime mold Dictyostelium showed that two genes Dok1 and Dhk1 were essential in the osmolarity sensing and development process (Schuster et al., 1996; Wang et al., 1996). A histidine kinase CKI1 was also implicated in the cytokinin signal transduction in Arabidopsis (Kakimoto, 1996). 1.1.2.1.1 The ethylene receptor family In Arabidopsis, there exist at least five members of ethylene receptors: ethylene response gene ETR1, ETR2, ethylene insensitive (EIN4), ethylene response sensor (ERS1) and ERS2 (Chang et al., 1993; Hua et al., 1995, 1998; Sakai et al., 1998). Among these receptors, ETR1, ETR2 and EIN4 contain a receiver domain at the C-terminal response regulator of the protein, while ERS1 and ERS2 lack this domain, implying that these receptors may use the receiver domain of some other proteins or utilize other response regulators since homodimerization of ERS1 has been observed in plants (Hall et al., 2000). On the basis of sequence and structural similarities, irrespective of the presence of the receiver domain, the receptor family can be further divided into two classes. The first class, consisting of ETR1 and ERS1, features three hydrophobic membrane-spanning subdomains at the N-terminal region and a well-conserved histidine kinase domain at the C-terminal part of the protein. The second class, which includes ETR2, EIN4 and ERS2, is predicted to have four stretches of hydrophobic amino acids. Interestingly, features of these two classes are also identified in other plant species such as tomato, peach, muskmelon, indicating that the mechanism of ethylene perception is likely conserved among all the flowering plants (Klee, 2002; Rasori et al., 2002; Sato-Nara et al., 1999). Besides Arabidopsis, the tomato receptor family is the most fully characterized in which the existing six members designated as LeETR1 to also fall into two classes. Functional compensation of these two classes of receptor genes is suggested by both absence of phenotype in single loss-of-functions mutant of Arabidopsis and also from the antisense suppression studies of tomato LeETR3 and LeETR4 receptor genes (Tieman et al., 2000). In the antisense LeETR4 transgenic tomato plants, reduction in LeETR4 mRNA level leads to enhanced ethylene sensitivity and responsiveness. This ethylene sensitivity could be eliminated by crossing with lines that overexpress LeETR3, suggesting the occurrence of functional redundancy among various ethylene receptors. 10 Horsch, R.B., Fry, J.E., Hoffman, N.L., Eichholtz, D., Rogers, S.G. and Fraley, R.T. (1985) A simple and general method for transferring genes into plants. Science 227, 12291231. Hua, J. and Meyerowitz, E.M. (1998) Ethylene responses are negatively regulated by a receptor gene family in Arabidopsis thaliana. Cell 94, 261-271. Hua, J., Chang, C., Sun, Q. and Meyerowitz, E.M. (1995) Ethylene insensitivity conferred by Arabidopsis ERS gene. Science 269, 1712-1714. Inoue, H., Nojima, H. and Okayama, H. (1990) High efficiency transformation of Escherichia coli with plasmids. Gene 96, 23-28. John, I., Drake, R., Farrell, A., Cooper, W., Lee, P., Horton, P. and Grierson, D. (1995) Delayed leaf senescence in ethylene-deficient ACC-oxidase antisense tomato plants: molecular and physiological analysis. The Plant Journal 7, 483-490. Johnson, P.R. and Ecker, J.R. (1998) The ethylene gas signal transduction pathway: A molecular perspective. Annual Review of Genetics 32, 227-254. Jorgensen, R.A., Cluster, P.D., English, J., Que, Q. and Napoli, C.A. (1996) Chalcone synthase cosuppression phenotypes in petunia flowers: comparison of sense vs. antisense constructs and single-copy vs. complex T-DNA sequences. Plant Molecular Biology 31, 957-973. Kakimoto, T. (1996) CKI1, a histidine kinase homolog implicated in cytokinin signaltransduction. Science 274, 982-985. Kapila, J., De Rycke, R., Van Montagu, M., and Angenon, G. (1997) An Agrobacteriummediated transient gene expression system for intact leaves. Plant Science 122, 101–108. Kende, H. (1993) Ethylene biosynthesis. Annual Review of Plant Physiology and Plant Molecular Biology 44, 283-307. 170 Kende, H. and Zeevaal, J.A.D. (1997) The five classic hormones. Plant Cell 9, 1197-1210. Kieber, J.J., Rothenberg, M., Roman, G., Feldmann, K.A. and Ecker, J.R. (1993) CTR1, a negative regulator of the ethylene response pathway in Arabidopsis, encodes a member of the Raf family of protein kinase. Cell 72, 427-441. Kim, S.W., Park, M.K. and Liu, J.R. (1996) High frequency plant regeneration via somatic embryogenesis in cell suspension cultures of coriander (Coriandrum sativum L.). Plant Cell Reports 15, 751-753. Klee, H, J. (2002) Control of ethylene-mediated processes in tomato at the level of receptors. Journal of Experimental Botany 53, 2057-2063. Klee, H.J., Hayford, M.B., Kretzmer, K.A., Barry, G.F. and Kishore, G.M. (1991) Control of ethylene synthesis by expression of a bacterial enzyme in transgenic tomato plants. Plant Cell 3, 1187-1193. Klein, T.M., Wolf, E.D., Wu, R. and Sanford, J.C. (1987) High-velocity microprojectiles for delivering nucleic acids into living cells. Nature 327, 70-73. Knoester, M., Vanloon, L.C., VandenHeuvel, J., Hennig, J., Bol, J.F. and Linthorst, H.M. (1998). Ethylene-insensitive tobacco lacks non-host resistance against soil-borne fungi. Proceedings of the National Academy of Sciences, USA 95, 1933-1937. Knoester, M., Pieterse, C.M.J., Bol, J.F. and Van Loon, L.C. (1999) Systemic resistance in Arabidopsis induced by rhizobacteria requires ethylene-dependent signaling at the site of application. Molecular Plant-Microbe Interactions 12, 720-727. Knuesel, M., Wan, Y., Xiao, Z., Holinger, E., Lowe, N., Wang, W. and Liu, X. (2003) Identification of novel protein-protein interactions using a versatile mammalian tandem affinity purification expression system. Molecular and Cellular Proteomics 2, 1225-1233. 171 Koch, K.A., Capitani, G., Gruetter, M.G. and Kirsch, J.F. (2001) The human cDNA for a homologue of the plant enzyme 1-aminocyclopropane-1-carboxylate synthase encodes a protein lacking that activity. Gene 272, 75-84. Koncz, C. and Schell, J. (1986) The promoter of TL-DNA gene controls of tissuespecific expression of chimaeric genes carried by a novel type of Agrobacterium binary vector. Molecular and General Genetics 204, 383-396. Krasko, A., Schröder, H.C., Perovic, S., Steffen, R., Kruse, M., Reichert, W., Muller, I.M. and Muller, W. E. G. (1999) Ethylene modulates gene expression in cells of the marine sponge suberites domuncula and reduces the degree of apoptosis. Journal of Biological Chemistry 274, 31524-31530. Kyriakis, J.M., App, H., Zhang, X.F., Banerjee, P., Brautigan, D.L., Rapp, U.R. and Avruch, J. (1992) Raf1 activates MAP kinase. Nature 358, 417-421. Laemmli, V.K. (1970) Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227, 680-685. Lawton, K., Weymann, K., Friedrich, L., Vernooij, B., Ukness, S. and Ryals, J. (1995) Systemic acquired resistance in Arabidopsis requires salicylic acid but not ethylene. Molecular Plant-Microbe Interactions 8, 863-870. Lehman, A., Black, R. and Ecker, J.R. (1996) HOOKLESS1, an ethylene responsive gene is required for differential cell elongation in the Arabidopsis hypocotyls. Cell 85,183-194. Liang, X., Abel, S., Keller, J.A., Shen, N.F. and Theologis, A. (1992) The 1-aminocyclocyclopropane-1-carboxylate synthase gene family of Arabidopsis thaliana. Proceedings of the National Academy of Sciences, USA 89, 11046-11050. Lichtenthaler, H.K. and Wellburn, A.R. (1983) Determination of total carotenoids and chlorophylls a and b of leaf extracts in different solvents. Biochemistry Society Transaction 11, 591-592. 172 Linstrom, J.T., Lei, C.H., Jones, M.L. and Woodson, W.R. (1999) Accumulation of ACC in petunia pollen is associated with expression of a pollen-specific ACC synthase late in development. Journal of the American Society of Horticultural Science 124, 145-151. Liu, Q., Singh, S. and Green, A. (2000) Genetic modification of cotton seed oil using inverted-repeat gene-silencing techniques. Biochemistry Society Transaction 28, 927-929. Lorenzo, O., Piqueras, R., Sanchez-Serrano, J. J. and Solano, R. (2003) ETHYLENE RESPONSE FACTOR1 integrates signals from ethylene and jasmonate pathways in plant defense. Plant Cell 15,165-178. Lund, S.T., Stall, R.E. and Klee, H.J. (1998) Ethylene regulates the susceptible response to pathogen infection in tomato. Plant Cell 10, 371-382. Luschnig, C., Gaxiola, R.A., Grisafi, P. and Fink, G.R. (1998) EIR1, a root-specific protein involved in auxin transport, is required for gravitropism in Arabidopsis thaliana. Genes and Development 12, 2175-2178. Maeda, T., Wurgler-Murphy, S.M. and Saito, H. (1994) A two-component system that regulates an osmosensing MAP kinase cascade in yeast. Nature 369, 242-245. Mauch, F., Hadwinger, L. A. and Boller, T. (1984) Ethylene: Symptom, not signal for the induction of chitinase and β-1,3-glucanase in pea pods by pathogens and elicitor. Plant Physiology 76, 607-611. Minkoff, R., Bales, E., Kerr, C. and Struss, W. (1999) Antisense oligonucleotide blockade of connexin expression during embryonic bone formation: evidence of functional compensation within a multigene family. Developmental Genetics 24, 43-56. Mulligan, G. J., Wong, J. and Jacks, T. (1998) p130 is dispensable in peripheral T lymphocytes: evidence for functional compensation by p107 and pRB. Molecular Cell Biology 18, 206-220. 173 Murashige, T. and Skoog, F. (1962) A revised medium for rapid growth and bioassay with tobacco tissue culture. Physiologia Plantarum 15, 473-497. Nakatsuka, A., Murachi, S., Okunishi, H., Shiomi, S., Nakano, R., Kubo, Y. and Inaba, A. (1998) Differential expression and internal feedback regulation of 1-aminocyclopro-pane1-carboxylate synthase, 1-aminocyclopropane-1-carboxylate oxidase, and ethylene receptor genes in tomato fruit during development and ripening. Plant Physiology 118, 1295-1305. Nathan, M.J., Goh, C.J. and Kumar, P.P. (1992) In vitro propagation of Heliconia psittacorum by bud culture. HortScience 27, 450-452. Nooden, L.D. (1988) Whole plant senescence. In: Nooden LD and Leopold AC (ed.) Senescence and Aging in Plants. Academic Press, New York, pp 391-439. Norman-Setterblad, C., Vidal, S. and Palva, E.T. (2000) Interacting signal pathways control defense gene expression in Arabidopsis in response to cell wall-degrading enzymes from Erwinia carotovora. Molecular Plant-Microbe Interaction 13, 430-438. Odell, J.T., Nagy, F. and Chua, N.H. (1985). Identification of DNA sequences required for activity of the cauliflower mosaic virus 35S promoter. Nature 313, 810-812. O'Donnell, P.J., Calvert, C., Atzorn, R., Wasternack, C., Leyser, H.M.O. and Bowles, D.J. (1996) Ethylene as a signal mediating the wound response of tomato plants. Science 274, 1914–1917. Oeller, P.W., Lu, M.W., Taylor, L.P., Pike, D.A. and Theologis, A. (1991) Reversible inhibition of tomato fruit senescence by antisense RNA. Science, 254, 437-439. Ouaked, F., Rozhon, W., Lecourieux, D. and Hirt, H. (2003) A MAPK pathway mediates ethylene signaling in plants. The EMBO Journal 22, 1282-1288. Overmyer, K., Tuominen, H., Kettunen, R., Betz, C., Langebartels, C., Sandermann, H. and Kangasjarvi, J. (2000) Ozone-sensitive Arabidopsis rcd1 mutant reveals opposite 174 roles for ethylene and jasmonate signaling pathways in regulating superoxide dependent cell death. Plant Cell 12, 1849-1862. Parkinson, J.S. (1993) signal-transduction schemes of bacteria. Cell 73, 857-871. Parkinson, J.S. and Kofoid, E.C. (1992) Communication modules in bacterial twocomponent regulators. Annual Review of Genetics 26, 71-112. Paton, A.W., Paton, J.C., Goldwater, P.N. and Manning, P.A. (1993) Direct detection of Escherichia coli Shiga-like toxin genes in primary fecal cultures by polymerase chain reaction. Journal of Clinical Microbiology 31, 3063-3067. Penmetsa, R.V. and Cook, D.R. (1997) A legume ethylene-insensitive mutant hyperinfected by its rhizobial symbiont. Science 275, 527-530. Penninckx, I.A.M.A., Eggermont, K., Terras, F.R.G., Thomma, B.P.H.J., De Samblanx, G.W., Buchala, A., Metraux, J.P., Manners, J.M. and Broekaert, W.F. (1996) Pathogeninduced systemic activation of a plant defense gene in Arabidopsis follows a salicylic acid-independent pathway. Plant Cell 8, 2309-2323. Penninckx, I.A.M.A., Thomma, B.P.H.J., Buchala, A., Metraux, J.P. and Broekaert, W.F. (1998) Concomitant activation of jasmonate and ethylene response pathways is required for induction of a plant defensin gene in Arabidopsis. Plant Cell 10, 2103-2113. Perovic, S., Seack, J., Gamulin, V., Muller, W.E. and Schroder, H.C. (2001) Modulation of intracellular calcium and proliferative activity of invertebrate and vertebrate cells by ethylene. BMC Cell Biology 2, 7-15. Pieterse, C. M. J., Van Wees, S. C. M., Van Pelt, J. A., Knoester, M., Laan, R., Gerrits, H., Weisbeek, P. J. and Van Loon, L. C. (1998) A novel signaling pathway controlling induced systemic resistance in Arabidopsis. Plant Cell 10, 1571-1580. 175 Pogson, B.J., Downs, C.G. and Davies, K.M. (1995) Differential of two 1aminocyclopropane-1-carboxylic acid genes in broccoli after harvest. Plant Physiology 108, 651-657. Posas, F., Wurgler-murphy, S.M., Maeda, T., Witten, E.A., Thai, T.C. and Saito, H. (1996) Yeast HOG1 MAP kinase cascade is regulated by a multistep phosphorylation mechanism in the SLN1-YPD1-SSK1 ‘two-component’ osmosensor. Cell 86, 865-875. Potuschak, T., Lechner, E., Parmentier, Y., Yanagisawa, S., Grava, S., Koncz, C. and Genschik, P. (2003) EIN3-dependent regulation of plant ethylene hormone signaling by two Arabidopsis F box proteins: EBF1 and EBF2. Cell 115, 679-689. Puig, O., Caspary, F., Rigaut, G., Rutz, B., Bouveret, E., Bragado-Nilsson, E., Wilm, M. and Seraphin, B. (2001) The tandem affinity purification (TAP) method: A general procedure of protein complex purification. Methods 24, 218–229. Ramadan, M.F., Kroh, L.W. and Morsel, J.T. (2003) Radical scavenging activity of black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.), and niger (Guizotia abyssinica Cass.) crude seed oils and oil fractions. Journal of Agricultural and Food Chemistry 51, 6961-6969. Rao, C.D., Goh, C.J. and Kumar, P.P. (1996) High frequency adventitious shoot regeneration from excised leaves of Paulownia spp. cultured in vitro. Plant Cell Reports 16, 204-209. Rao, M.V., Lee, H., Creelman, R.A., Mullet, J.E. and Davis, K.R. (2000) Jasmonic acid signaling modulates ozone-induced hypersensitive cell death. Plant Cell 12, 1633-646. Rasori, A., Ruperti, B., Bonghi, C., Tonutti, P. and Ramina, A. (2002) Characterization of two putative ethylene receptor genes expressed during peach fruit development and abscission. Journal of Experimental Botany 53, 2333-2339. 176 Ravanel, S., Gakiere, B., Job, D. and Douce, R. (1998) The specific features of methionine biosynthesis and metabolism in plants. Proceedings of the National Academy of Sciences, USA 95, 7805-7812. Rieu, I., Wolters-Arts, M., Derksen, J., Mariani, C. and Weterings, K. (2003) Ethylene regulates the timing of anther dehiscence in tobacco. Planta 217, 131-137. Rigaut, G., Shevchenko, A., Rutz, B., Wilm, M., Mann, M. and Seraphin, B. (1999) A generic protein purification method for protein complex characterization and proteome exploration. Nature Biotechnology 17, 1030-1032. Rodriguez, F.I., Esch, J.J., Hall, A.E., Binder, B.M., Schaller, G.E. and Bleecker, A.B. (1999) A copper cofactor for the ethylene receptor ETR1 from Arabidopsis. Science 283, 996-998. Rohila, J.S., Chen, M., Cerny, R. and Fromm, M.E. (2004) Improved tandem affinity purification tag and methods for isolation of protein heterocomplexes from plants. The Plant Journal 38, 172-181. Rivas, S., Romeis, T. and Jones, J. D. (2002) The Cf-9 disease resistance protein is present in an approximately 420-kilodalton heteromultimeric membrane-associated complex at one molecule per complex. Plant Cell 14, 689-702. Roman, G., Lubarsky, B., Kieber, J.J., Rothenberg, M. and Ecker, J.R. (1995) Genetic analysis of ethylene signal-transduction pathway in Arabidopsis thaliana: five novel mutant loci integrated into a stress response pathway. Genetics 139, 1393-1409. Ross, A. F. and Williamson, C. E. (1951) physiologically active emanations from virusinfected plants. Phytopathology 41, 431-438. Ryals, J.A., Neuenschwander, U.H., Willits, M.G., Molina, A., Steiner, H.Y. and Hunt, M.D. (1996) Systemic acquired resistance. Plant Cell 8, 1809-1819. 177 Sakai, H., Hua, J., Chen, Q.G., Chang, C., Medrano, L.J., Bleecker, A.B. and Meyerowitz, E.M. (1998) ETR2 is an ETR1-like gene involved in ethylene signaling in Arabidopsis. Proceedings of the National Academy of Sciences, USA 95, 5812-5817. Sambrook, J., Fritsch, E.F. and Maniatis, T. (1989) Molecular cloning- a laboratory manual, 2nd edition. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York. Sanger, F., Nicklen, S. and Coulson, A.R. (1977) DNA sequencing with chain-terminating inhibitors. Proceedings of the National Academy of Sciences, USA 74, 5463-5467. Sato-Nara, K., Ken-Ichi, Y., Katsumi, H., Kazushige, H., Mitsuru, K. and Hiroshi, E. (1999) Stage- and tissue-specific expression of ethylene receptor homolog genes during fruit development in muskmelon. Plant Physiology 120, 321-330. Sato, T. and Theologis, A. (1989) Cloning the mRNA encoding 1-aminocyclopropane-1carboxylate synthase, the key enzyme for ethylene biosynthesis in plants. Proceedings of the National Academy of Sciences, USA 86, 6621-6625. Savin, K.W., Baudinette, S.C., Graham, M.W., Michael, M.Z., Nugent, G.D., Lu, C., Chandler, S.F. and Cornish, E.C. (1995) Antisense ACC oxidase RNA delays carnation petal senescence. HortScience 30, 970-972. Schaller, G.E., Ladd, A.N., Lanahan, M.B., Spanbauer, J.M. and Bleeker, A.B. (1995) The ethylene response mediator ETR1 from Arabidopsis forms a disulfide dimer. Journal of Biological Chemistry 270, 12526-12530. Schuster, S.C., Noegel, A.A., Oehme, F., Gerisch, G. and Simon, M.I. (1996) The hybrid histidine kinase DokA is part of the osmotic response system of Dictyostelium. The EMBO Journal 15, 3880-3889. Shah, J., Kachroo, P. and Klessig, D.F. (1999) The Arabidopsis ssi1 mutation restores pathogenesis-related gene expression in npr1 plants and renders defensin gene expression salicylic acid dependent. Plant Cell 11, 191-206. 178 Shaw, J.F., Chen, H.H., Tsai, M.F., Kuo, C.I. and Huang, L.C. (2002) Extended flower longevity of Petunia hybrida plants transformed with boers, a mutated ERS gene of Brassica oleracea. Molecular Breeding 9, 211-216. Shibuya, K., Barry, K. G., Ciardi, J. A., Loucas, H. M., Underwood, B. A., Nourizadeh, S., Ecker, J. R., Klee, H. J. and Clark, D. G. (2004) The central role of PhEIN2 in ethylene responses throughout plant development in petunia. Plant Physiology 136, 2900-2912. Shibuya, K, Nagata, M., Tanikawa, N., Yoshioka, T., Hashiba, T. and Satoh S. (2002) Comparison of mRNA levels of three ethylene receptors in senescing flowers of carnation (Dianthus caryophyllus L). Journal of Experimental Botany 53, 399-406. Sivasubramaniam, S., Vanniasingham, V.M., Tan, C.T. and Chua, N.H. (1995) Characterization of HEVER, a novel stress-induced gene from Hevea brasiliensis. Plant Molecular Biology 29, 173-178. Spanu, P. and Boller, T. (1989) Ethylene biosynthesis in tomato plants infected by Phytophthora infestans. Journal of Plant Physiology 135, 533-537. Spanu, P., Grosskopf, D.G., Felix, G. and Boller, T. (1994) The apparent turnover of 1aminocyclopropane-1-carboxylate synthase in tomato cells is regulated by proteinphosphorylation and dephosphorylation. Plant Physiology 106, 529–535. Stashenko, E.E., Puertas, M.A. and Marinez, J.R. (2002) SPME determination of volatile aldehydes for evaluation of in-vitro antioxidant activity. Analytical and Bioanalytical Chemistry 273, 70-74. Stearns, J.C. and Glick, B.R. (2003) Transgenic plants with altered ethylene biosynthesis and perception. Biotechnology Advances 21, 193-210. Stepanova, A.N. and Ecker, J.R. (2000) Ethylene signaling: from mutants to molecules. Current Opinion in Plant Biology 3, 353-360. 179 Stock, A., Koshland, D. E. Jr. and Stock, J. (1985) Homologies between the Salmonella typhimurium CheY protein and protein involved in the regulation of chemotaxis, member protein synthesis and sporulation. Proceedings of the National Academy of Sciences, USA 82, 7989-7993. Stock, J. B., Stock, A. M. and Mottonenn, J. M. (1990) Signal transduction in bacteria. Nature 344, 395-400. Swanston-Flatt, S.K., Day, C., Bailey, C.J. and Flatt, P.R. (1990) Traditional plant treatments for diabetes. Studies in normal and streptozotocin diabetic mice. Diabetologia 33, 462-464. Takamatsu, N., Ishikawa, M., Meshi, T. and Okada, Y. (1987) Expression of bacterial chioramphenicol acetyltransferase gene in tobacco plants mediated by TMV-RNA. The EMBO Journal 6, 307-311. Tang, X., Gomes, A., Bhatia, A. and Woodson, W.R. (1994) Pistil-specific and ethyleneregulated expression of 1-aminocyclopropane-1-carboxylate oxidase genes in petunia flowers. Plant Cell 6, 1227-1239. Tang, X., Wang, H., Brandt, A.S. and Woodson, W.R. (1993) Organization and structure of the 1-aminocyclopropane-1-carboxylate oxidase gene family from Petunia hybrida. Plant Molecular Biology 23, 1151-1164. Tang, X. and Woodson, W.R. (1996) Temporal and spatial expression of 1-Aminocyclopropane-1-carboxylate oxidase mRNA following pollination of immature and mature petunia flowers. Plant Physiology 112, 503-511. Tarwadi, K. and Agte, V. (2003) Potential of commonly consumed green leafy vegetables for their antioxidant capacity and its linkage with the micronutrient profile. International Journal of Food Sciences and Nutrition 54, 417-425. 180 Taylor, J.E., Grosskopf, D.G., McGaw, B.A., Horgan, R. and Scott, I.M. (1988) Apical localization of 1-aminocyclopropane-1-carboxylic acid and its conversion to ethylene in etiolated pea seedlings. Planta 174,112-114. Terai, H. (1993) Behaviors of 1- aminocyclopropane-1-carboxylic acid (ACC) and ACC synthase responsible for ethylene-production in normal and mutant (nor and rin) tomato fruits at various ripening stages. Journal of the Japanese Society for Horticultural Science 61, 805-812. Terajima, Y., Nukui, H., Kobayashi, A., Fujimoto, S., Hase, S., Yoshioka, T., Hashiba, T. and Satoh, S. (2001) Molecular cloning and characterization of a cDNA for a novel ethylene receptor, NT-ERS1, of tobacco (Nicotiana tabacum L.). Plant and Cell Physiology 42, 308-313. Theologis, A. (1992) One rotten apple spoiled the whole bushel: the role of ethylene in fruit ripening. Cell 70, 181-184. Thomma, B.P.H.J., Eggermont, K., Tierens, K.F.M.J. and Broekaert, W.F. (1999) Requirement of functional ethylene-insensitive gene for efficient resistance of Arabidopsis to infection by Botrytis cinerea. Plant Physiology 121, 1093-1101. Thomma, B.P.H.J., Penninckx, I.A.M.A., Broekaert, W.F. and Cammue, B.P.A. (2001) The complexity of disease signaling in Arabidopsis. Current Opinion in Immunology 13, 63-68. Tieman, D. and Klee, H.J. (1999) Differential expression of two novel members of the tomato ethylene-receptor family. Plant Physiology 120, 165-172. Tieman, D.V., Taylor, M.G., Ciardi, J.A. and Klee, H.J. (2000) The tomato ethylene receptors NR and LeETR4 are negative regulators of ethylene response and exhibit functional compensation within a multigene family. Proceedings of the National Academy of Sciences, USA 97, 5663-5668. 181 Vahala, J., Schlagnhaufer, C.D. and Pell, E.J. (1998) Induction of an ACC synthase cDNA by ozone in light-grown Arabidopsis thaliana leaves. Physiologia Plantarum 103, 45-50. Van Loon, L.C. (1997) Induced resistance in plants and the role of pathogenesis-related proteins. European Journal of Plant Pathology 103, 753-765. Van Peer, R., Niemann, G. J. and Schippers, B. (1991) Induced resistance and phytoalexin accumulation in biological control of Fusarium wilt of carnation by Pseudomonas sp. strain WCS417r. Phytopathology 81, 728-734. Van Wees, S.C., de Swart, E.A., Van Pelt, J.A., van loon, L.C. and Pieterse, C.M. (2000) Enhanced of induced disease resistance by simultaneous activation of salicylate- and jasmonate-dependent defense pathways in Arabidopsis thaliana. Proceedings of the National Academy of Sciences, USA 97, 8711-8716. Vaquero, C., Sack, M., Chandler, J., Drossard, J., Schuster, F., Monecke, M., Schillberg, S. and Fischer, R. (1999) Transient expression of a tumor-specific single-chain fragment and chimeric antibody in tobacco leaves. Proceedings of the National Academy of Sciences, USA 96, 11128-11133. Vernooij, L., Friedrich, A., Morse, R., Reist, R., Kolditz-Jawhar, E., Ward, S., Uknes, H., Kessmann. and Ryals, J. (1994) Salicylic acid is not the translocated signal inducing systemic acquired resistance, but is required in signal transduction. Plant Cell 6, 959-965. Verwoerd, T.C., Dekker, B.M. and Hoekerma, A. (1989) A small-scale procedure for the rapid isolation of plant RNAs. Nucleic Acids Research 7, 2362. Vogel, J.P., Woeste, K.E., Theologis, A. and Kieber, J.J. (1998) Recessive and dominant mutations in the ethylene biosynthetic gene ACS5 of Arabidopsis confer cytokinin insensitivity and ethylene overproduction, respectively. Proceedings of the National Academy of Sciences, USA 95, 4766-4771. 182 Wang, N., Shaulsky, G., Escalante, R. and Loomis, W.F. (1996) A two-component histidine kinase gene that functions in Dictyostelium development. The EMBO Journal 15, 3890-3898. Wang, W., Hall, A. E., O'Malley, R. and Bleecker, A. B. (2002) Canonical histidine kinase activity of the transmitter domain of the ETR1 ethylene receptor from Arabidopsis is not required for signal transmission. Proceedings of the National Academy of Sciences, USA 100, 352-357. Weber, N., Richter, K.-D., Schulte, E. and Mukherjee, K. D. (1995) Petroselinic acid from dietary triacylglycerols reduces the concentration of arachidonic acid in tissue lipids of rats. Journal of Nutrition 125, 1563-1568. Weber, N., Klein, E. and Mukherjee, K.D. (1997) Metabolism of dietary petroselinic acid: a dead-end metabolite of desaturation/chain elongation reactions. Nutrition Research 17, 89-97. Wei, G., Kloepper, J. W. and Tuzun, S. (1991) Induction of systemic resistance of cucumber to Colletotrichum orbiculare by select strains of plant growth-promoting rhizobacteria. Phytopathology 81, 1508-1512. Whitehead, C.S., Halevy, A.H. and Reid, M.S. (1984) Roles of ethylene and ACC in pollination and wound-induced senescence of Petunia hybrida flowers. Physiologia Plantarum 61, 643-648. Whitelaw, C.A., Lyssenko, N.N., Chen, L., Zhou, D., Mattoo, A.K. and Tucker, M.L. (2002) Delayed abscission and shorter internodes correlate with a reduction in the ethylene receptor LeETR1 transcript in transgenic tomato. Plant Physiology 128, 978-987. Wilkinson, J.Q., Lanahan, M.B., Yen, H.C., Giovannoi, J.J. and Klee, H.J. (1995) An ethylene-inducible component of signal transduction encoded by Never-ripe. Science 270, 1807-1809. 183 Wilkinson, J.Q., Lanahan, M.B., Clark, D.G., Bleecker, A.B., Chang, C., Meyerowitz, E.M. and Klee, H.J. (1997) A dominant mutant receptor from Arabidopsis confers ethylene insensitivity in heterologous plants. Nature Biotechnology 15, 444-447. Wolters-Arts, M., Derksen, J., kooijman, J.W. and Mariani, C. (1996) Stigma development in Nicotiana tabacum. Cell death in transgenic plants as a marker to follow cell fate at high resolution. Sexual Plant Reproduction 9, 243-254. Woodson, W.R., Park, K.Y., Drory, A., Larson, P.B. and Wang, H. (1992) Expression of ethylene biosynthetic pathway transcripts in senescing carnation flowers. Plant Physiology 99, 526-532. Yang, S.F. and Hoffman, N.E. (1984) Ethylene biosynthesis and its regulation in higher plants. Annual Review of Plant Physiol 35, 155-189. Yang, Y.O., Shah, J. and Klessig, D.F. (1997) Signal perception and transduction in defense responses. Genes and Development 11, 1621-1639. Yau, C. P., Wang, L., Yu, M., Zee, S. Y. and Yip, W. K. (2004) Differential expression of three genes encoding an ethylene receptor in rice during development, and in response to indole-3-acetic acid and silver ions. Journal of Experimental Botany 55, 547 - 556. Yoshida, S., Ito, M., Nishida, I. and Watanabe, A. (2001) Isolation and RNA gel blot analysis of genes that could serve as potential molecular markers for leaf senescence in Arabidopsis thaliana. Plant and Cell Physiology 42, 170-178. Yu, H., Ito, T., Wellmer, F. and Meyerowitz, E.M. (2004) Repression of AGAMOUSLIKE 24 is a crucial step in promoting flower development. Nature Genetics 36, 157-161. Zhang, J. S., Xie, C., Shen, Y. G. and Chen, S.Y. (2001) A two-component gene (NTHK1) encoding a putative ethylene receptor homolog is both developmentally and stress regulated in tobacco. Theoretical and Applied Genetics 102, 815—824. 184 Zheng, Z., Maidji, E., Tugizov, S. and Pereira, L. (1996) Mutations in the carboxyterminal hydrophobic sequence of human cytomegalovirus glycoprotein B alter transport and protein chaperone binding. Journal of Virology 70, 8029-8040. 185 [...]... down-regulation of only one of the six known receptor genes, LeETR4 in tomato, which results in enhanced ethylene responsiveness (Tieman et al., 2000) 1.1.2.2 The ethylene signal transduction pathway 12 1.1.2.2.1 CTR1 and the MAPK-kinase cascade Isolation and characterization of CTR1 has led to substantial insights on the nature of ethylene signal transduction CTR1 was placed downstream of the ethylene receptors... induction of a subset of plant defense genes including PR-3, PR-4 and PDF1.2 failed in Arabidopsis ein2 and coi1, the plants with defects in ethylene perception and JA signaling, separately (Penninckx et al., 1998) The induction of PDF1.2 upon infection by Alternaria brassicicola requires concomitant presence of both ethylene and JA signaling pathways (Penninckx et al., 1996, 1998.) A recent study on ethylene. .. phenotype of these flowers was different from that of the control as their petals remained firm and finally decolorized, instead of the typical ethylenedependent petal inrolling during senescence The ability of these receptors to function in heterologous plants suggests that this pathway of hormone recognition and response is highly conserved and can be manipulated to the benefit of horticulture and agriculture... al., 2002) 19 1.2.2 Ethylene and tissue-specific responses 1.2.2.1 Ethylene responses in root and hypocotyl The EIR1 gene may be a possible target of ethylene pathway in the roots since the eir1 mutant seedlings showed ethylene- insensitive phenotype only in the roots but normal responses in apical hook and hypocotyl (Roman et al., 1995) Mutant analysis places EIR1 downstream of CTR1 and EIN2 (Luschnig... integration of ethylene and auxin signaling pathways in the regulation of apical hook formation (Lehman et al., 1996) HLS1 transcripts are increased by ethylene treatment and decreased in ethylene- insensitive ein2 mutant Overexpression of HLS1 in transgenic Arabidopsis caused constitusive hypocotyl hook curvature Inhibition of auxin transport also results in the similar phenotype Expression of two auxin-responsive... also showed ethylene- insensitive phenotypes, such as delayed senescence of petals and leaves, as well as insensitivity of seedlings to ACC treatment 1.2.3 Ethylene responses in animals Some genes that respond to ethylene have been isolated from bacteria, marine sponge (invertebrate) and mammalian cell cultures (vertebrate) recently (Rodriguez et al., 1999; Wang et al., 2002) A portion of an ethylene binding... protein from Synechocystis sp has high sequence similarity to the transmembrane domain of ETR1 The sponge Suberites domuncula provides the first example of ethylene signaling in an animal because this organism could respond to ethylene both physiologically and at molecular levels (Krasko et al., 1999) Ethylene could reduce the starvation-induced apoptosis and up-regulate expression of two genes, SDERR and. .. copper-delivery pathway is required for generating a functional ethylene receptor All the Arabidopsis receptors are negative regulators of the ethylene response (Hua and Meyerowitz, 1998; Cancel et al., 2002) This was determined by analysis of quadruple mutants that have constitutive ethylene responses The later generated ers1; etr1 loss-offunction double mutants exhibited the same responses is consistent... expression levels of these genes are spatially and temporally controlled throughout development In Arabidopsis, expression pattern of ETR1 and ERS1 differs in each tissue although they are ubiquitously expressed LeETR4 and LeETR5 in tomato are mainly expressed in reproductive organs and less in vegetative tissues They are differently regulated during flower development (Tieman and Klee, 1999) These genes also... that the different receptors might play different roles during plant development Therefore, it was proposed that ethylene signal transduction occurs through parallel paths that partially intersect (Whitelaw et al., 2002) 1.1.2.1.2 Physiological action of receptors The mechanism of ethylene perception of receptors has been largely revealed by the recent genetic and biochemical studies In Arabidopsis, ETR1 . compensation of these two classes of receptor genes is suggested by both absence of phenotype in single loss -of- functions mutant of Arabidopsis and also from the antisense suppression studies of tomato. in Arabidopsis (Kakimoto, 1996). 1.1.2.1.1 The ethylene receptor family In Arabidopsis, there exist at least five members of ethylene receptors: ethylene response gene ETR1, ETR2, ethylene. 1.1.2.1 Ethylene perception and the action of ethylene receptor( s) As shown in Figure1.2, ethylene is perceived by plants through a family of integral membrane receptors. These receptors