role of arabidopsis bhlh transcription factors myc2, myc3 and myc4 in defense against herbivory
TRANSCRIPT
Role of Arabidopsis bHLH transcription factors MYC2, MYC3 and MYC4in defense against herbivory
www.unil.ch/reymondlab
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
JA signalling
from Staswick, 2008
Stimulus (wound, herbivore)
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
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
Trancriptome analysis of myc234 mutant
Schweizer et al. (2013) Plant Cell
The majority of highly dowregulated genes in myc234 are GS-pathway genes
Glucosinolate pathway genes are downregulated in myc234 mutant
Glucosinolates are defense compounds in Brassicaceae
Aliphatic-GS Indole-GS
Rapid profiling of intact glucosinolates
Glauser et al. (2012) Phytochem Anal
UHPLC-QTOFMS
Glucosinolate levels are highly reduced in myc234 mutants
ConstitutiveInduced (S. littoralis)
Schweizer et al. (2013) Plant Cell
MYCs control GS accumulation in seeds
Two-choice assay
The specialist P. brassicae prefersglucosinolate-containing plants
Oviposition
Contrasting insect performance on Arabidopsis glucosinolate mutants
Schweizer et al. (2013) Plant Cell
Change of feeding behaviour of a generalist herbivore
Schweizer et al. (2013) Plant Cell
Non-uniform ditribution of GSSchroff et al. (2008) PNAS
Are GS-related MYBs controlled MYC2,3,4?
downregulated genes
MYC2MYC3MYC4
MYC2MYC3MYC4
?
?
MYC2,3,4 physically interact with MYBs
Schweizer et al. (2013) Plant Cell
but: GS-related MYBs donot interact with JAZs
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
Model for MYC234-dependent activation of glucosinolate genes
defense againstgeneralist herbivores
Role of other insect-inducible transcription factors
S. littoralis performance
S. littoralis-induced genes
Schweizer et al. (2013) Front. Plant Sci.
A hierarchy of transcription factors
MYBs
glucosinolates
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)