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First published online May 8, 2008; 10.1104/pp.108.117523 Plant Physiology 147:1347-1357 (2008) © 2008 American Society of Plant Biologists The AP2/ERF Domain Transcription Factor ORA59 Integrates Jasmonic Acid and Ethylene Signals in Plant Defense1,[W]Institute of Biology Leiden, Clusius Laboratory, Leiden University, 2333 AL Leiden, The Netherlands (M.P., M.A., A.C., J.M.); and Plant-Microbe Interactions, Department of Biology, Utrecht University, 3584 CH Utrecht, The Netherlands (M.D.V., C.M.J.P.)
Plant defense against pathogens depends on the action of several endogenously produced hormones, including jasmonic acid (JA) and ethylene. In certain defense responses, JA and ethylene signaling pathways synergize to activate a specific set of defense genes. Here, we describe the role of the Arabidopsis (Arabidopsis thaliana) APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) domain transcription factor ORA59 in JA and ethylene signaling and in defense. JA- and ethylene-responsive expression of several defense genes, including PLANT DEFENSIN1.2 (PDF1.2), depended on ORA59. As a result, overexpression of ORA59 caused increased resistance against the fungus Botrytis cinerea, whereas ORA59-silenced plants were more susceptible. Several AP2/ERF domain transcription factors have been suggested to be positive regulators of PDF1.2 gene expression based on overexpression in stably transformed plants. Using two different transient overexpression approaches, we found that only ORA59 and ERF1 were able to activate PDF1.2 gene expression, in contrast to the related proteins AtERF1 and AtERF2. Our results demonstrate that ORA59 is an essential integrator of the JA and ethylene signal transduction pathways and thereby provide new insight into the nature of the molecular components involved in the cross talk between these two hormones.
Plant fitness and survival are dependent on the ability to mount fast and highly adapted responses to diverse environmental stress conditions. Perception of stress signals results in the production of one or more of the secondary signaling molecules jasmonic acid (JA), ethylene, and salicylic acid.
JA is a major intermediate signaling molecule in defense against wounding, herbivores, and certain pathogens (Turner et al., 2002
Several components of the corresponding signal transduction pathways have been characterized. The coronatine insensitive1 (coi1) mutant is affected in a gene encoding an F-box protein that is important for all known JA responses, including defense against necrotrophic pathogens (Thomma et al., 1998
A crucial step in JA- and ethylene-dependent defense responses is the rapid transcription of genes coding for antimicrobial proteins or for enzymes involved in the biosynthesis of protective secondary metabolites. Therefore, studying the mechanisms whereby the expression of these defense-related genes is regulated is of major importance to understand signal transduction pathways and plant responses to environmental stress. In the past several years, a number of transcription factors regulating defense-related genes have been functionally characterized. Several of these regulatory proteins belong to a subgroup, known as the ERF family, of the large plant-specific APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) superfamily (Nakano et al., 2006 Here, we report the functional characterization of the transcription factor ORA59 (At1g06160), another member of the ERF family. Our findings show that ORA59 integrates JA and ethylene signals to regulate the expression of defense genes such as PDF1.2 and ChiB, providing important new insights into the nature of the molecular components involved in JA-responsive gene expression and in the cross talk between JA and ethylene.
ORA59 Gene Expression Is Controlled by the JA and Ethylene Signal Transduction Pathways
In a family-wide screening, Atallah (2005)
Genome-Wide Identification of Putative ORA59 Target Genes
To characterize the genes regulated by ORA59, we performed a genome-wide transcriptome analysis of transgenic XVE-ORA59 plants overexpressing ORA59 in an estradiol-inducible manner from the XVE expression module. The full Arabidopsis genome was covered using the Agilent Arabidopsis 3 Oligo microarray platform. Microarray data analyses revealed that 86 genes showed significantly increased expression levels of at least 2-fold in plants treated for 16 h with 2 µM estradiol to overexpress the ORA59 transgene. Many of these genes are known to be involved in defense against biotic or abiotic stress, signaling, or primary or secondary metabolism (Supplemental Table S1). Several defense-related genes, such as PDF1.2, HEL, and ChiB, were highly expressed in plants overexpressing the ORA59 gene. The expression of these genes is also induced by JA or ethylene and is superinduced by a combination of both (Potter et al., 1993
ORA59 Functions Downstream of COI1 The expression studies indicated that only a small proportion of genes induced by JA or JA and ethephon (around 5%–10%) were regulated by ORA59 (Supplemental Table S1; Supplemental Fig. S1). We hypothesized that, for these genes, ORA59 forms the terminal component of the ethylene and jasmonate signal transduction pathways and that it serves as the integrator of the JA and ethylene signal inputs, thereby determining the final expression output for this set of defense genes. To test whether ORA59 functions downstream of the JA signal transduction component COI1, we investigated whether ORA59 overexpression would lead to target gene expression without requiring COI1. We introduced the XVE-ORA59 expression module in the coi1-1 mutant background and analyzed the expression of PDF1.2, HEL, and ChiB after treatment with the inducer estradiol. As shown in Figure 2 , estradiol-induced expression of ORA59 resulted in high expression levels of the target genes PDF1.2 and HEL in a COI1-independent manner. In contrast, estradiol-induced expression of ORA59 in the coi1-1 mutant background did not lead to high expression of the ChiB gene, indicating that regulation of the ChiB gene by ORA59 is controlled by COI1-dependent molecular mechanisms. As expected, treatment with JA and ethephon induced the expression of all defense genes tested in the wild type but not in the coi1-1 mutant background.
These results demonstrate that for some genes, ORA59 functions downstream from COI1, which is compatible with the hypothesis that ORA59 is the terminal integrator of the JA and ethylene signal inputs for a subset of JA- and ethylene-responsive genes, including PDF1.2 and HEL.
To assess the role of ORA59 in a loss-of-function approach, ORA59 gene expression was silenced using the RNA interference (RNAi) technique. Two copies of the ORA59 full-length open reading frame were cloned in an inverted repeat orientation in front of the cauliflower mosaic virus (CaMV) 35S promoter, and the construct was transformed to plants. Under normal growth conditions, all transgenic ORA59-silenced lines displayed no visible aberrant phenotype compared with wild-type plants. ORA59 mRNA levels in 10-d-old seedlings from different silenced lines were monitored by RNA-blot analyses using a probe corresponding to the 3' untranslated region of ORA59. In most lines, ORA59 mRNA was undetectable after treatment with JA for 30 min (Fig. 3A ). In contrast, transgenic line 5 showed wild-type ORA59 mRNA accumulation in response to JA, whereas line 13 showed a reduced ORA59 mRNA level. Induction of the PDF1.2 and HEL genes in response to 8 h of JA treatment was severely compromised in those ORA59-silenced lines with undetectable ORA59 mRNA (Fig. 3B). Furthermore, the reduction in PDF1.2 and HEL transcript abundance was inversely correlated with the ORA59 mRNA level in individual lines, indicating that the JA-induced expression of these defense genes was dependent on ORA59. JA-responsive expression of PDF1.2 was also impaired in 5-week-old RNAi-ORA59 plants grown in soil treated with methyl jasmonate for 6 h (Fig. 3C).
Gene expression in response to hormone treatments was further analyzed using the transgenic line RNAi-ORA59 9. In agreement with previous findings, RNA-blot analyses using a probe corresponding to a gene-specific part of the ORA59 coding region showed that treatments with JA and/or ethephon did not induce the accumulation of ORA59 mRNA in 2-week-old seedlings of the RNAi-ORA59 9 line compared with the control line (Fig. 4A ). Instead, a smeary signal was observed when hybridizing with this probe. This autoradiographic pattern observed in the ORA59-silenced lines is likely due to the detection of the complete inverted repeat intron RNA transcribed from the silencing construct and its degradation products, based on similar hybridization patterns with the PDK intron separating the two inverted ORA59 repeats (data not shown). In the ORA59-silenced plants, the JA- and ethephon-induced expression of several genes identified by the microarray analysis, including PDF1.2, AN5-AT, ChiB, and HEL genes, was dramatically reduced compared with the control line (Fig. 4A). In contrast, the defense gene VSP1, which was not a target gene of ORA59 according to the microarray analysis, was induced to similar levels in response to JA in both ORA59-silenced and control plants.
To verify that the silencing effects of the RNAi construct on defense gene expression were specific for ORA59, the mRNA levels of ERF1 and AtERF2, encoding two possibly functionally equivalent transcription factors, were determined (Fig. 4A). The JA- and ethephon-induced gene expression levels of ERF1 and AtERF2 in the ORA59-silenced line were similar to those observed in the control line. ERF1 and ORA59 form a small subgroup within group IX of the ERF family, which includes a third protein, AtERF15, encoded by gene At2g31230 (Nakano et al., 2006 Taken together, these results demonstrate that ORA59 is responsible for the activation of a subset of JA- and ethylene-responsive genes, including PDF1.2, ChiB, and HEL, and that ORA59 is an essential node of convergence of the concomitant activation of the JA and ethylene signal transduction pathways, which is absolutely required for the expression of these genes.
In Arabidopsis, the JA and ethylene signal transduction pathways are involved in resistance against the necrotrophic fungus B. cinerea (Thomma et al., 1998
For disease resistance tests, transgenic lines constitutively overexpressing the ORA59 gene from the CaMV 35S promoter were constructed. In general, independent 35S:ORA59 lines showed a severe dwarf phenotype under normal growth conditions (Supplemental Fig. S3), similar to plants overexpressing ERF1 (Solano et al., 1998
To test whether ORA59 also controls defense gene expression in response to infection with other fungi, 5-week-old wild-type plants, ORA59-silenced plants, pad3-1 mutant plants impaired in camalexin biosynthesis (Glazebrook and Ausubel, 1994  ), and JA-insensitive coi1-1 mutant plants were inoculated with A. brassicicola. RNA-blot analyses of infected and systemic leaves revealed that A. brassicicola infection induced ORA59 gene expression in wild-type plants both locally and systemically (Fig. 5C). In coi1-1 mutant plants and ORA59-silenced plants, the expression levels of ORA59 and its target gene PDF1.2 in response to A. brassicicola were strongly reduced (Fig. 5C). Disease ratings were assessed at 7 d after inoculation. In comparison with wild-type plants, the pad3-1 and coi1-1 mutant plants developed severe symptoms upon A. brassicicola inoculation (data not shown), confirming previous findings showing that these mutants have enhanced susceptibility toward this pathogen (Thomma et al., 1998, 1999b). In contrast to these mutants, the level of basal resistance against A. brassicicola in ORA59-silenced plants did not differ from that of wild-type plants (data not shown). Thus, although ORA59 is required for the expression of PDF1.2 and presumably of other ORA59 target genes after A. brassicicola infection, ORA59 and its target genes do not play an important role in the resistance against this pathogen under these experimental conditions.
Our results show that ORA59 is a crucial regulator of several defense-related genes, including PDF1.2. ORA59 loss-of-function studies revealed that no other AP2/ERF domain transcription factor or member of another class of transcriptional regulators was able to activate the expression of PDF1.2 in response to JA (Fig. 3) or JA + ethephon treatments (Fig. 4) or to infection with B. cinerea or A. brassicicola (Fig. 5). These results appear to contradict a previous report showing that constitutive overexpression of the AP2/ERF domain transcription factor ERF1 gave rise to increased PDF1.2 gene expression (Solano et al., 1998
Both experimental approaches demonstrate that ORA59 and ERF1 are able to function as activators of the PDF1.2 promoter, whereas AtERF1 and AtERF2 do not activate the PDF1.2 promoter when inducibly or transiently expressed.
JA is a key regulatory signaling molecule in plant defense. An important aspect of JA action is its synergistic interaction with ethylene in the induction of a subset of defense-related genes. In this study, we investigated the function of ORA59, a member of the ERF transcription factor family in Arabidopsis. We demonstrated that ORA59 integrates JA and ethylene signal inputs. By doing so, ORA59 controls the expression of a subset of JA- and ethylene-dependent genes, including PDF1.2. Expression of these genes in response to these signals, or after perception of certain pathogens, depends on ORA59, and no other transcription factor, including ERF1 or AtERF2, can bypass the requirement for ORA59.
The current commonly accepted model pointed to ERF1 as a key element in the integration of JA and ethylene signals for the regulation of defense genes in response to pathogens (Lorenzo et al., 2003 Taken together, these data suggest functional redundancy between ORA59 and ERF1 in JA- and ethylene-dependent defense responses. However, the finding that expression of ORA59-regulated genes, including PDF1.2, in response to JA and/or ethylene treatments was severely compromised in ORA59-silenced plants revealed the essential role of ORA59. Moreover, plants silencing the ORA59 gene showed increased susceptibility to B. cinerea infection, presumably by impaired expression of the ORA59-regulated defense genes, further supporting the crucial role of ORA59 in defense. The results also demonstrate that ERF1 alone is not sufficient to support wild-type levels of defense gene expression in response to JA and/or ethylene or to B. cinerea or A. brassicicola infection.
Our findings are summarized in the model in Figure 7
. The specific function of ERF1 in JA and ethylene signaling is still unclear. ERF1 has been suggested to be part of a linear ethylene signal transduction cascade in which the transcription factor EIN3 was suggested to induce ERF1 gene expression in response to ethylene (Solano et al., 1998
The signal transduction cascade integrating ethylene and JA response pathways plays important biological functions in plants, in particular in microbial disease resistance responses. The whole purpose of signal transduction in cells is to activate a transcription factor, which in turn regulates the expression of response genes. The identification of a crucial transcription factor that integrates the JA and ethylene signals lies at the heart of a comprehensive understanding of the transduction of these signals. Our results add an important molecular component involved in JA signal transduction and in cross talk between JA and ethylene, as described among others in the Science Signal Transduction Knowledge Environment (Gfeller et al., 2006 ), and will have consequences for future studies on more upstream signal transduction components.
One question to be addressed in future studies is whether ORA59 is a crucial link in JA/ethylene-responsive COI1-dependent gene expression solely because it needs to be synthesized de novo upon induction of ORA59 gene expression or whether there is an additional level of regulation acting on ORA59 protein activity. The JA-responsive transcription factor AtMYC2, which regulates a distinct subset of JA-responsive COI1-dependent genes, is also synthesized de novo in response to JA via gene induction, but it is additionally regulated at the protein level by interaction with putative repressors belonging to the jasmonate ZIM domain (JAZ) family (Chini et al., 2007
Biological Materials, Growth Conditions, and Treatments Arabidopsis (Arabidopsis thaliana) wild-type plants, coi1-1, ein2-1, and pad3-1 mutants, and all transgenic plants are in the genetic background of ecotype Columbia Col-0. Surface-sterilized seeds were grown for 10 d at 21°C in a growth chamber (16-h-light/8-h-dark photoperiod at 200 µE m–2 s–1 at 70% relative humidity) on a modified half-strength Murashige and Skoog medium (MA medium) solidified with 0.6% agar. Fifteen to 20 seedlings per sample were transferred to 50-mL polypropylene tubes (Sarstedt) containing 10 mL of MA medium and incubated on a shaker at 120 rpm for an additional 4 d before treatment. Seedlings were treated with 50 µM JA (Sigma-Aldrich), 1 mM ethephon (an ethylene-releasing compound; Sigma), or a combination of JA and ethephon. As controls, seedlings were treated with the respective solvents dimethyl sulfoxide (DMSO; 0.1%), sodium phosphate, pH 7 (0.5 mM), or a combination of both. Homozygous JA-insensitive coi1-1 seedlings were selected on MA medium containing 50 µM JA. Transgenic plants carrying an XVE expression module were treated with 2 µM estradiol (Sigma) dissolved in DMSO. In order to reach similar expression levels of the transgene, transgenic XVE-ORA59-TAP and XVE-ERF1-TAP plants were treated with 4 µM estradiol. Induction treatment with methyl jasmonate was performed by dipping 5-week-old soil-grown plants in an aqueous solution containing 50 µM methyl jasmonate (Serva, Brunschwig Chemie) and 0.01% Silwet L-77. Control plants were dipped in 0.01% Silwet L-77.
For the constitutive overexpressing plants, the ORA59 (At1g06160) and hemagglutinin-tagged AtERF1 (At4g17500) open reading frames were cloned into pRT101 in front of the CaMV 35S promoter. The 35S cassettes were cloned into the binary vector pCAMBIA1300 (http://www.cambia.org). The binary vector pCAMBIA1301 carrying the GUS gene under the control of the CaMV 35S promoter was used to generate control lines (1301 lines). For the RNAi-ORA59 lines, the ORA59 open reading frame was cloned as an inverted repeat into the pHANNIBAL vector (GenBank accession no. AJ311872). For the RNAi control line GUS 5, the GUS open reading frame was cloned into pHANNIBAL. The pHANNIBAL expression cassettes were cloned into the binary vector pART27. For the estradiol-inducible XVE lines, the ORA59, AtERF1, AtERF2 (At5g47220), GUS, and C-terminal TAP-tagged ORA59 and ERF1 (At3g23240) open reading frames were cloned into the binary vector pER8. Details of plasmid construction are described in Supplemental Materials and Methods S1. Binary vectors carrying the different constructs were introduced into Agrobacterium tumefaciens, and plants were transformed by floral dip. Transgenic plants were selected on MA medium containing 100 mg L–1 timentin and 20 mg L–1 hygromycin, except for pART27 transformants, which were selected on 100 mg L–1 timentin and 25 mg L–1 kanamycin. The XVE-ORA59;coi1-1 plants were obtained by fertilizing homozygous coi1-1 ovules with pollen from transgenic XVE-ORA59 plants. Heterozygous coi1/COI1 F1 siblings containing the transgene were selected on MA medium containing 20 mg L–1 hygromycin and were allowed to self-pollinate. F2 siblings homozygous for the coi1 mutation and carrying the XVE-ORA59 transgene were selected on MA medium containing 50 µM JA and 20 mg L–1 hygromycin.
All genotypes were grown for 2 weeks on solid MA medium before transferring to sterile soil and cultivated for another 3 weeks at 24°C in a growth chamber (8-h-light/16-h-dark photoperiod at 200 µE m–2 s–1) at 70% relative humidity. Because of the early-stage dwarf phenotype, seeds from transgenic line 35S:ORA59 17 were sown 2 weeks earlier than the other genotypes. Therefore, soil-potted plants from this genetic background were allowed to grow for 5 weeks in order to reach a stage with rosette leaf size suitable for pathogen infection (Supplemental Fig. S3).
Botrytis cinerea and Alternaria brassicicola were grown on potato dextrose agar plates for 2 weeks at 22°C. Spores were harvested as described by Broekaert et al. (1990)
Disease ratings were assigned to the inoculated leaves of each plant, as indicated in the legend to Figure 5. A Pearson
Total RNA was extracted from frozen tissue by hot phenol/chloroform extraction followed by overnight precipitation with 2 M lithium chloride and two washes with 70% ethanol and resuspended in water. Ten-microgram RNA samples were subjected to electrophoresis on 1.5% agarose/1% formaldehyde gels and blotted to GeneScreen nylon membranes (Perkin-Elmer Life Sciences). DNA fragments used as probes were PCR amplified from Arabidopsis genomic DNA. Primer sequences are listed in Supplemental Materials and Methods S1. For reverse transcription-PCR, aliquots of 20 µg of total RNA were treated with DNaseI, phenol extracted, and precipitated with ethanol. RNA integrity was verified on gel. Aliquots of 4 µg of DNaseI-treated RNA were reverse-transcribed with oligo(dT)12-18 and Moloney murine leukemia virus reverse transcriptase (Promega). Aliquots corresponding to 0.16 µg of reverse-transcribed RNA were amplified for 20 cycles of 1 min at 92°C, 45 s at 50°C, and 45 s at 72°C using SuperTaq (SphaeroQ) and primers specific for the ORA59, AtERF15, and Actin7 (At5g09810) genes. In pilot experiments with increasing cycle numbers, it was determined that 20 cycles were well within the linear range of amplification for all three genes. Control PCR containing equivalent amounts of DNaseI-treated RNA that was not reverse transcribed did not yield bands. Aliquots corresponding to 0.06 µg of reverse-transcribed and PCR-amplified RNA were run on 5% polyacrylamide gels. Ethidium bromide-stained bands were recorded on a Bio-Rad GelDoc XR system and were quantified using Bio-Rad Quantity One software. Details of microarray experiments are given in Supplemental Materials and Methods S1.
Protoplasts prepared from an Arabidopsis Columbia cell suspension were cotransformed with a reporter plasmid carrying PDF1.2 promoter-GUS, effector plasmids carrying AtERF1, AtERF2, ERF1, or ORA59 genes fused to the CaMV 35S promoter, and a reference plasmid carrying the Renilla LUCIFERASE (LUC) gene under the control of the CaMV 35S promoter. As controls, PDF1.2 promoter-GUS was cotransformed with the corresponding empty effector vectors. Protoplasts were transformed with the three constructs in a ratio of 1:1:3 (GUS:LUC:effector plasmid). Protoplasts were harvested at 18 h after transformation and frozen in liquid nitrogen. GUS reporter gene expression was related to LUC expression to correct for transformation and protein extraction efficiency. Average GUS-LUC ratios from triplicate experiments were expressed relative to the respective vector controls.
The following materials are available in the online version of this article.
We thank Adel Zarei for construction of the 35S:AtERF1, 35S:ERF1, and pPDF1.2:GUS plasmids used for transient assays. Received February 5, 2008; accepted April 29, 2008; published May 8, 2008.
1 This work was supported by the Research Council for Earth and Life Sciences with financial aid from the Netherlands Organization for Scientific Research (grant no. 811.36.001 to M.P. and grant no. 865.04.002 to M.D.V. and C.M.J.P.) and by a Marie Curie Intra-European Fellowship within the European Community Fifth Framework Programme (contract no. QLK5–CT–2002–51650 for A.C.). 
2 Present address: Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY 14853. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Johan Memelink (j.memelink{at}biology.leidenuniv.nl).
[W] The online version of this article contains Web-only data. www.plantphysiol.org/cgi/doi/10.1104/pp.108.117523 * Corresponding author; e-mail j.memelink{at}biology.leidenuniv.nl.
Alonso JM, Hirayama T, Roman G, Nourizadeh S, Ecker JR (1999) EIN2, a bifunctional transducer of ethylene and stress responses in Arabidopsis. Science 284: 2148–2152 Atallah M (2005) Jasmonate-responsive AP2-domain transcription factors in Arabidopsis. PhD thesis. University of Leiden, Leiden, The Netherlands Berrocal-Lobo M, Molina A, Solano R (2002) Constitutive expression of ETHYLENE-RESPONSE FACTOR1 in Arabidopsis confers resistance to several necrotrophic fungi. Plant J 29: 23–32[CrossRef][Web of Science][Medline] Broekaert WF, Terras FRG, Cammue BPA, Van Der Leyden J (1990) An automated quantitative assay for fungal growth. FEMS Microbiol Lett 69: 55–60[CrossRef][Web of Science] Brown RL, Kazan K, McGrath KC, Maclean DJ, Manners JM (2003) A role for the GCC-box in jasmonate-mediated activation of the PDF1.2 gene of Arabidopsis. Plant Physiol 132: 1020–1032 Chini A, Fonseca S, Fernández G, Adie B, Chico JM, Lorenzo O, García-Casado G, López-Vidriero I, Lozano FM, Ponce MR, et al (2007) The JAZ family of repressors is the missing link in jasmonate signalling. Nature 448: 666–671[CrossRef][Medline] Feys BJF, Benedetti CE, Penfold CN, Turner JG (1994) Arabidopsis mutants selected for resistance to the phytotoxin coronatine are male-sterile, insensitive to methyl jasmonate, and resistant to a bacterial pathogen. Plant Cell 6: 751–759 Gfeller A, Liechti R, Farmer EE (2006) Arabidopsis jasmonate signaling pathway. Sci STKE 2006: cm1 Glazebrook J, Ausubel FM (1994) Isolation of phytoalexin-deficient mutants of Arabidopsis and characterization of their interactions with bacterial pathogens. Proc Natl Acad Sci USA 91: 8955–8959 Gutterson N, Reuber TL (2004) Regulation of disease resistance pathway by AP2/ERF transcription factors. Curr Opin Plant Biol 7: 465–471[CrossRef][Web of Science][Medline] Guzman P, Ecker JR (1990) Exploiting the triple response of Arabidopsis to identify ethylene-related mutants. Plant Cell 2: 513–523 Kunkel BN, Brooks DM (2002) Cross-talk between signaling pathways in pathogen defense. Curr Opin Plant Biol 5: 325–331[CrossRef][Web of Science][Medline] Lorenzo O, Piqueras R, Sánchez-Serrano JJ, Solano R (2003) ETHYLENE RESPONSE FACTOR1 integrates signals from ethylene and jasmonate pathways in plant defense. Plant Cell 15: 165–178 McGrath KC, Dombrecht B, Manners JM, Schenk PM, Edgar CI, Maclean DJ, Scheible WR, Udvardi MK, Kazan K (2005) Repressor- and activator-type ethylene response factors functioning in jasmonate signaling and disease resistance identified via a genome-wide screen of Arabidopsis transcription factor gene expression. Plant Physiol 139: 949–959 Nakano T, Suzuki K, Fujimura T, Shinshi H (2006) Genome-wide analysis of the ERF gene family in Arabidopsis and rice. Plant Physiol 140: 411–432 Oñate-Sánchez L, Anderson JP, Young J, Singh KB (2007) AtERF14, a member of the ERF family of transcription factors, plays a nonredundant role in plant defense. Plant Physiol 143: 400–409 Penninckx IAMA, Eggermont K, Terras FRG, Thomma BPHJ, De Samblanx GW, Buchala A, Metraux J-P, Manners JM, Broekaert WF (1996) Pathogen-induced systemic activation of a plant defensin gene in Arabidopsis follows a salicylic acid-independent pathway. Plant Cell 8: 2309–2323[Abstract] Penninckx IAMA, Thomma BPHJ, Buchala A, Metraux JP, Broekaert WF (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 Potter S, Uknes S, Lawton K, Winter AM, Chandler D, DiMaio J, Novitzky R, Ward E, Ryals J (1993) Regulation of a hevein-like gene in Arabidopsis. Mol Plant Microbe Interact 6: 680–685[Web of Science][Medline] Puig O, Caspary F, Rigaut G, Rutz B, Bouveret E, Bragado-Nilsson E, Wilm M, Seraphin B (2001) The tandem affinity purification (TAP) method: a general procedure of protein complex purification. Methods 24: 218–229[CrossRef][Web of Science][Medline] Solano R, Stepanova A, Chao Q, Ecker JR (1998) Nuclear events in ethylene signaling: a transcriptional cascade mediated by ETHYLENE-INSENSITIVE3 and ETHYLENE-RESPONSE-FACTOR1. Genes Dev 12: 3703–3714 Thines B, Katsir L, Melotto M, Niu Y, Mandaokar A, Liu G, Nomura K, He SY, Howe GA, Browse J (2007) JAZ repressor proteins are targets of the SCFCOI1 complex during jasmonate signalling. Nature 448: 661–665[CrossRef][Medline] Thomma BPHJ, Eggermont K, Penninckx IAMA, Mauch-Mani B, Vogelsang R, Cammue BPA, Broekaert WF (1998) Separate jasmonate-dependent and salicylate-dependent defense-response pathways in Arabidopsis are essential for resistance to distinct microbial pathogens. Proc Natl Acad Sci USA 95: 15107–15111 Thomma BPHJ, Eggermont K, Tierens KFM-J, Broekaert WF (1999a) Requirement of functional Ethylene-insensitive 2 gene for efficient resistance of Arabidopsis to infection by Botrytis cinerea. Plant Physiol 121: 1093–1101 Thomma BPHJ, Nelissen I, Eggermont K, Broekaert WF (1999b) Deficiency in phytoalexin production causes enhanced susceptibility of Arabidopsis to the fungus Alternaria brassicicola. Plant J 19: 163–171[CrossRef][Web of Science][Medline] Turner JG, Ellis C, Devoto A (2002) The jasmonate signal pathway. Plant Cell (Suppl) 14: S153–S164 Xie DX, Feys BF, James S, Nieto-Rostro M, Turner JG (1998) COI1: an Arabidopsis gene required for jasmonate-regulated defense and fertility. Science 280: 1091–1094 This article has been cited by other articles:
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ABSTRACT
RESULTS
2 test was used to evaluate whether distributions of disease ratings were statistically different between the wild type and other genotypes. For gene expression analysis, infected and noninfected leaves from several inoculated plants of each genotype were collected at days 2 and 4 after inoculation with B. cinerea and at days 2 and 7 after inoculation with A. brassicicola. 
