MYC2: the master in action.
TL;DR: Mechanistic new insights are revealed into the mode of action of this versatile TF that is involved in JA-regulated plant development, lateral and adventitious root formation, flowering time, and shade avoidance syndrome.
About: This article is published in Molecular Plant.The article was published on 2013-05-01 and is currently open access. It has received 698 citations till now. The article focuses on the topics: Jasmonate & Arabidopsis.
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TL;DR: Important new components of jasmonate signalling including its receptor were identified, providing deeper insight into the role ofJASMONATE signalling pathways in stress responses and development.
1,868 citations
Cites background from "MYC2: the master in action."
...The cross-talk between SA and JA has been observed in many Arabidopsis accessions (Koornneef and Pieterse, 2008), and is even transmitted to the next generation (Luna et al., 2012)....
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...Most of them accumulate very rapidly (within minutes) in wounded Arabidopsis or tomato leaves....
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...The JAZ proteins have their counterparts in five DELLA proteins of Arabidopsis which are active in GA signalling; GAI/SLY is the homologue of COI1, GID1 is the GA receptor and the DELLAs RGL and RGL1-like (RGL1, RGL2 and RGL3) are the repressors (Schwechheimer, 2012)....
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...Most evidence derives from the microarray-based transcriptome analysis of CJ-treated Arabidopsis plants (Matthes et al., 2010)....
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...MYCs belong to the bHLH domain-containing TFs, and act as both activator and repressor of distinct JA-responsive gene expressions in Arabidopsis (Lorenzo et al., 2004)....
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TL;DR: Evidence supporting the growth-defense tradeoff concept is addressed, as well as known interactions between defense signaling and growth signaling, which should provide a foundation for the development of breeding strategies to maximize crop yield to meet rising global food and biofuel demands.
1,035 citations
Cites background from "MYC2: the master in action."
...These results suggest that, in response to pathogen or herbivore attack, degradation of JAZ proteins makes more DELLA proteins available for interaction with and inhibition of PIF transcription factors as part of a mechanism to inhibit growth (Figure 4) (Yang et al., 2012; Kazan and Manners, 2013)....
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TL;DR: Mechanistic new insights into the mode of action of these hormones in plant abiotic stress tolerance are revealed, which will contribute to the development of crop plants tolerant to a wide range of stressful environments.
595 citations
TL;DR: A triple mutant of MYC2, MYC3, and MYC4 transcription factors is devoid of glucosinolates and more sensitive to attack by a generalist insect, underlines the importance of GS in shaping plant interactions with adapted and nonadapted herbivores.
Abstract: Arabidopsis thaliana plants fend off insect attack by constitutive and inducible production of toxic metabolites, such as glucosinolates (GSs). A triple mutant lacking MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that are known to additively control jasmonate-related defense responses, was shown to have a highly reduced expression of GS biosynthesis genes. The myc2 myc3 myc4 (myc234) triple mutant was almost completely devoid of GS and was extremely susceptible to the generalist herbivore Spodoptera littoralis. On the contrary, the specialist Pieris brassicae was unaffected by the presence of GS and preferred to feed on wild-type plants. In addition, lack of GS in myc234 drastically modified S. littoralis feeding behavior. Surprisingly, the expression of MYB factors known to regulate GS biosynthesis genes was not altered in myc234, suggesting that MYC2/MYC3/MYC4 are necessary for direct transcriptional activation of GS biosynthesis genes. To support this, chromatin immunoprecipitation analysis showed that MYC2 binds directly to the promoter of several GS biosynthesis genes in vivo. Furthermore, yeast two-hybrid and pull-down experiments indicated that MYC2/MYC3/MYC4 interact directly with GS-related MYBs. This specific MYC–MYB interaction plays a crucial role in the regulation of defense secondary metabolite production and underlines the importance of GS in shaping plant interactions with adapted and nonadapted herbivores.
412 citations
Cites background from "MYC2: the master in action."
...Thus, MYC2, and potentially MYC3 and MYC4, emerges as a central component that physically interacts with multiple factors to control defense, hormonal, and development programs (Kazan and Manners, 2013)....
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TL;DR: An improved understanding of phytohormone intervention strategies employed by pests and pathogens during their interactions with plants will ultimately lead to the development of new crop protection strategies.
Abstract: The constant struggle between plants and microbes has driven the evolution of multiple defense strategies in the host as well as offense strategies in the pathogen. To defend themselves from pathogen attack, plants often rely on elaborate signaling networks regulated by phytohormones. In turn, pathogens have adopted innovative strategies to manipulate phytohormone-regulated defenses. Tactics frequently employed by plant pathogens involve hijacking, evading, or disrupting hormone signaling pathways and/or crosstalk. As reviewed here, this is achieved mechanistically via pathogen-derived molecules known as effectors, which target phytohormone receptors, transcriptional activators and repressors, and other components of phytohormone signaling in the host plant. Herbivores and sap-sucking insects employ obligate pathogens such as viruses, phytoplasma, or symbiotic bacteria to intervene with phytohormone-regulated defenses. Overall, an improved understanding of phytohormone intervention strategies employed by pests and pathogens during their interactions with plants will ultimately lead to the development of new crop protection strategies.
383 citations
Cites background from "MYC2: the master in action."
...…acting as negative regulators of the JA pathway and allows the master regulator MYC2 to activate JA-responsive gene expression while attenuating SA responses and SA accumulation (Katsir et al., 2008; Melotto et al., 2008; Lee et al., 2013; Zheng et al., 2012; reviewed by Kazan and Manners, 2013)....
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References
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TL;DR: The eFP Browser software is easily adaptable to microarray or other large-scale data sets from any organism and thus should prove useful to a wide community for visualizing and interpreting these data sets for hypothesis generation.
Abstract: Summary In conclusion, the eFP Browser is a convenient tool forinterpreting and visualizing gene expression and other data. Notonly is it valuable for its compatibility to existing resources but ithas also been loaded with several useful data sets. The variousmodes and other features allow the user to extract an array ofconclusions and/or generate useful hypotheses. We hope thatmany researchers will be able to use the eFP Browser both tounderstand particular microarray or other experimental results, aswell as to communicate their own findings. MATERIALS AND METHODS The eFP Browser is implemented in Python and makes use of thePython Imaging Library (PIL) Build 1.1.5 (www.python.org),which we modified to provide an optimized flood pixel re-placement function called replaceFill, and other Python modules,as described on the eFP Browser development homepage. Theinputs for the eFP Browser are illustrated in Figure 1. Apictographic representation of the sample collection as a Targa-based image is required, as is an XML control file, shown in detailin Figure 1B. Two other inputs are a database of gene identifiersand their appropriate microarray element lookups and annota-tions, and a database of gene expression values for the givensamples. In the case of the Arabidopsis, Cell and Mouse eFPBrowsers, we have mirrored publicly-available microarray datafrom several sources – described in the Data Sources andsubsequent two sections – in our Bio-Array Resource [10]. Theseinputs are used by the eFP Browser algorithm to generate anoutput image for a user’s gene identifier.The eFP Browser algorithm itself is programmed in an object-oriented manner. The main program, efpWeb.cgi, is responsiblefor the creation of the HTML code for the user interface andpresentation of the output image. It calls on four modules tocomplete the task. These modules are 1) efp.py, which performsmost of the functions for the generation of the output image,including the parsing of the XML control file, average andstandard deviation calculations, fold-change relative to controlvalue calculations, and image map HTML code; 2) efpDb.py,which connects to the gene expression, microarray element andannotation databases, and returns the appropriate values uponbeing called; 3) efpImg.py, which formulates the actual colourreplace calls on the Targa input image; and 4) efpXML.py, whichidentifies the XML control files that are present in the eFPBrowser’s data directory. These are displayed to the user in theData Source drop-down, thus obviating the need to have themhard-coded in the main efpWeb.cgi program.In the case of the Cell eFP Browser, data in the SUBAdatabase indicate the presence of a given protein in a particularsubcellular location, either based on computational methods or asmolecularly documented by mass spectrometric analysis ofsubcellular fractions, GFP fusions etc. [11]. We have used a simpleheuristic to turn these data into a confidence score for a given geneproduct’s presence in a given subcellular compartment:confidence~X
2,416 citations
TL;DR: Evidence is emerging that beneficial root-inhabiting microbes also hijack the hormone-regulated immune signaling network to establish a prolonged mutualistic association, highlighting the central role of plant hormones in the regulation of plant growth and survival.
Abstract: Plant hormones have pivotal roles in the regulation of plant growth, development, and reproduction. Additionally, they emerged as cellular signal molecules with key functions in the regulation of immune responses to microbial pathogens, insect herbivores, and beneficial microbes. Their signaling pathways are interconnected in a complex network, which provides plants with an enormous regulatory potential to rapidly adapt to their biotic environment and to utilize their limited resources for growth and survival in a cost-efficient manner. Plants activate their immune system to counteract attack by pathogens or herbivorous insects. Intriguingly, successful plant enemies evolved ingenious mechanisms to rewire the plant’s hormone signaling circuitry to suppress or evade host immunity. Evidence is emerging that beneficial root-inhabiting microbes also hijack the hormone-regulated immune signaling network to establish a prolonged mutualistic association, highlighting the central role of plant hormones in the regulation of plant growth and survival.
2,132 citations
TL;DR: The results suggest a model in which jasmonate ligands promote the binding of the SCFCOI1 ubiquitin ligase to and subsequent degradation of the JAZ1 repressor protein, and implicate theSCFCOi1–JAZ1 protein complex as a site of perception of the plant hormone JA–Ile.
Abstract: Jasmonate and related signalling compounds have a crucial role in both host immunity and development in plants, but the molecular details of the signalling mechanism are poorly understood. Here we identify members of the jasmonate ZIM-domain (JAZ) protein family as key regulators of jasmonate signalling. JAZ1 protein acts to repress transcription of jasmonate-responsive genes. Jasmonate treatment causes JAZ1 degradation and this degradation is dependent on activities of the SCF(COI1) ubiquitin ligase and the 26S proteasome. Furthermore, the jasmonoyl-isoleucine (JA-Ile) conjugate, but not other jasmonate-derivatives such as jasmonate, 12-oxo-phytodienoic acid, or methyl-jasmonate, promotes physical interaction between COI1 and JAZ1 proteins in the absence of other plant proteins. Our results suggest a model in which jasmonate ligands promote the binding of the SCF(COI1) ubiquitin ligase to and subsequent degradation of the JAZ1 repressor protein, and implicate the SCF(COI1)-JAZ1 protein complex as a site of perception of the plant hormone JA-Ile.
2,061 citations
TL;DR: The identification of JASMONATE-INSENSITIVE 3 (JAI3) and a family of related proteins named JAZ (jasmonate ZIM-domain), in Arabidopsis thaliana and the existence of a regulatory feed-back loop involving MYC2 and JAZ proteins, which provides a mechanistic explanation for the pulsed response to jasmonate and the subsequent desensitization of the cell.
Abstract: Jasmonates are essential phytohormones for plant development and survival. However, the molecular details of their signalling pathway remain largely unknown. The identification more than a decade ago of COI1 as an F-box protein suggested the existence of a repressor of jasmonate responses that is targeted by the SCF(COI1) complex for proteasome degradation in response to jasmonate. Here we report the identification of JASMONATE-INSENSITIVE 3 (JAI3) and a family of related proteins named JAZ (jasmonate ZIM-domain), in Arabidopsis thaliana. Our results demonstrate that JAI3 and other JAZs are direct targets of the SCF(COI1) E3 ubiquitin ligase and jasmonate treatment induces their proteasome degradation. Moreover, JAI3 negatively regulates the key transcriptional activator of jasmonate responses, MYC2. The JAZ family therefore represents the molecular link between the two previously known steps in the jasmonate pathway. Furthermore, we demonstrate the existence of a regulatory feed-back loop involving MYC2 and JAZ proteins, which provides a mechanistic explanation for the pulsed response to jasmonate and the subsequent desensitization of the cell.
1,991 citations
TL;DR: Results indicate that both AtMYC2 and AtMYB2 proteins function as transcriptional activators in ABA-inducible gene expression under drought stress in plants.
Abstract: In Arabidopsis, the induction of a dehydration-responsive gene, rd22, is mediated by abscisic acid (ABA). We reported previously that MYC and MYB recognition sites in the rd22 promoter region function as cis-acting elements in the drought- and ABA-induced gene expression of rd22. bHLH- and MYB-related transcription factors, rd22BP1 (renamed AtMYC2) and AtMYB2, interact specifically with the MYC and MYB recognition sites, respectively, in vitro and activate the transcription of the β-glucuronidase reporter gene driven by the MYC and MYB recognition sites in Arabidopsis leaf protoplasts. Here, we show that transgenic plants overexpressing AtMYC2 and/or AtMYB2 cDNAs have higher sensitivity to ABA. The ABA-induced gene expression of rd22 and AtADH1 was enhanced in these transgenic plants. Microarray analysis of the transgenic plants overexpressing both AtMYC2 and AtMYB2 cDNAs revealed that several ABA-inducible genes also are upregulated in the transgenic plants. By contrast, a Ds insertion mutant of the AtMYC2 gene was less sensitive to ABA and showed significantly decreased ABA-induced gene expression of rd22 and AtADH1. These results indicate that both AtMYC2 and AtMYB2 proteins function as transcriptional activators in ABA-inducible gene expression under drought stress in plants.
1,931 citations