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The WRKY superfamily of plant
transcription factors
Introduction
Wrky
▶ WRKY (pronounced‘worky’) proteins, a large family of transcriptional regulators
that has to date only been found in plants.
▶ The WRKY domain is defined by the conserved amino acidsequence WRKYGQK
at its N-terminal end, together with a novel zinc-finger-like motif
▶ Many WRKY proteins having a regulatory
function in the response to pathogen infection and other stresses.
▶ levels of WRKY mRNA, protein and DNA-binding activity havebeen reported
to be induced by infection with viruses
oomycetes
fungal
elicitors9
Signaling substances such as salicylic acid
▶ Comparative expression studies with several AtWRKY genes
also suggest that certain family members have a role in the regulation
of senescence.
▶ Transcript levels of AtWRKY4, 6, 7 and 11 are enhanced
in senescent leaves.
▶ W boxes have been described as positive cis-acting elements
upregulating transcription.
1.group I : two WRKY domains
group II: one WRKY domains
group III: newly define group
2.(Pc)sweet potato (Ib), Arabidopsis (At),
tobacco (Nt), cucumber (Cs) and wild
oat (Af ).
WRKY domains are black
nuclear localization signals are blue
leucine zippers are pink
serine–threonine-rich regions are yellow
glutamine-rich regions are purple
proline-rich regions are green
acidic regions are red
Fig. Phylogenetic analysis of 58 members of the AtWRKY family.
Results
Targets of AtWRKY6 regulation
during plant senescence
and pathogen defense
ABSTRACT
In Arabidopsis,
▶ WRKY factors large gene family of plant-specific transcriptional regulators
controlling several types of plant stress responses.
▶ we identified targets of the senescence- and defense-associated WRKY6 factor.
▶ WRKY6 was found to suppress its own promoter activity,
indicating negative autoregulation.
▶ WRKY6 positively influenced the senescence- and pathogen defenseassociated PR1 promoter activity, most likely involving NPR1 function.
▶ One novel identified target gene, SIRK, encodes a receptor-like protein kinase,
whose developmental expression is strongly induced specifically
during leaf senescence. SIRK is dependent on WRKY6 function.
▶ Senescing leaves of wrky6 knockout mutants showed a drastic reduction,
green leaves of WRKY6 overexpression lines showed clearly elevated SIRK
▶ The SIRK gene promoter was activated by WRKY6 in vivo
The Plant Journal
En-1 transposon insertion
Figure 1. Identification of wrky6 knockout mutants
Figure 2. WRKY6 overexpression lines.
The Plant Journal
SAG:salicyilc
acid glucoside
ELI:plant defence
Related gene
The Plant Journal
Knock out
Figure 3. Repressor activity of WRKY6.
promotor
promotor
overexepression
promotor
promotor
GUS
WRKY Knock out gene
GUS
WRKY overexpression
Pathogen
Rhizobacterium
JA response
SA
jar1
NahG
JA response
ethylene response
Ethylene response
etr1
NPR
npr1
Defensive compounds
ISR
PRS
SAR
PDF1.2
The Plant Journal
Figure . Nuclear localization of endogenous AtWRKY6.
The Plant Journal
Figure 4. Effect of WRKY6 overexpression on PR1 and NPR1.
R:root transcripts.R1-R154
P:aerieal part transcripts P1-P63
Table 1. cDNA-AFLP fragments and homologies to sequences
in the Arabidopsis database
Figure 5. Dependence of SIRK gene expression on WRKY6
Figure 6. Specificity of the WRKY6-SIRK promoter interaction
SIRK
WRKY6
?
Necrotic
Pathogen
infection
Systemic
signal
SA
NPR1
SAR
Gene
expression
Enhanced
Pathogen
resistance