role of arabidopsis bhlh transcription factors myc2, myc3 and myc4 in defense against herbivory
TRANSCRIPT
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Role of Arabidopsis bHLH transcription factors MYC2, MYC3 and MYC4in defense against herbivory
www.unil.ch/reymondlab
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A B C D
Predators
Indirect defenses
Direct defenses
Induction of defense genes
Emission of volatile compounds
Induced defenses in response to herbivory
TFs
Jasmonate pathway
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JA signalling
from Staswick, 2008
Stimulus (wound, herbivore)
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Spodoptera littoralis
WT coi1-1 WT coi1-1
Spodoptera littoralis
JA signalling is crucial for defense against herbivory
The majority of insect-responsive genes are not induced in coi1-1
7 days of larval feeding
Reymond et al. (2004) Plant Cell
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Role of bHLH transcription factors MYC2, MYC3 and MYC4
Growth of Spodoptera littoralis larvae on myc mutants
Fernandez-Calvo et al. (2011) Plant Cell
Sub-family of Arabidopsis bHLH transcription factors
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Trancriptome analysis of myc234 mutant
Schweizer et al. (2013) Plant Cell
The majority of highly dowregulated genes in myc234 are GS-pathway genes
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Glucosinolate pathway genes are downregulated in myc234 mutant
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Glucosinolates are defense compounds in Brassicaceae
Aliphatic-GS Indole-GS
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Rapid profiling of intact glucosinolates
Glauser et al. (2012) Phytochem Anal
UHPLC-QTOFMS
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Glucosinolate levels are highly reduced in myc234 mutants
ConstitutiveInduced (S. littoralis)
Schweizer et al. (2013) Plant Cell
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MYCs control GS accumulation in seeds
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Two-choice assay
The specialist P. brassicae prefersglucosinolate-containing plants
Oviposition
Contrasting insect performance on Arabidopsis glucosinolate mutants
Schweizer et al. (2013) Plant Cell
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Change of feeding behaviour of a generalist herbivore
Schweizer et al. (2013) Plant Cell
Non-uniform ditribution of GSSchroff et al. (2008) PNAS
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Are GS-related MYBs controlled MYC2,3,4?
downregulated genes
MYC2MYC3MYC4
MYC2MYC3MYC4
?
?
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MYC2,3,4 physically interact with MYBs
Schweizer et al. (2013) Plant Cell
but: GS-related MYBs donot interact with JAZs
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MYC2 binds to the promoter of GS biosynthesis genes
ChIP-seq analysis of MYC2-GFP plants
CYP79B3 (Atg22330) SOT16 (Atg74100)
Consensus MYC binding site(G-box element)
GS biosynthesis genescontain MYC- and MYB-binding sites
Schweizer et al. (2013) Plant Cell
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Model for MYC234-dependent activation of glucosinolate genes
defense againstgeneralist herbivores
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Role of other insect-inducible transcription factors
S. littoralis performance
S. littoralis-induced genes
Schweizer et al. (2013) Front. Plant Sci.
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A hierarchy of transcription factors
MYBs
glucosinolates
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Acknowledgements
Fabian Schweizer
Gaetan Glauser & Ted TurlingsSPSW Chemical Analysis Service, Neuchâtel
Patricia Fernandez-Calvo & Roberto SolanoDept. of Plant Molecular Genetics, Madrid
Mark Zander, Mathew Lewsey & Joe EckerThe Salk Institute, La Jolla (CA)