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The WRKY superfamily of plantThe WRKY superfamily of planttranscription factorstranscription factors
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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
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▶ 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.
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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 blacknuclear localization signals are blue leucine zippers are pink serine–threonine-rich regions are yellowyellow glutamine-rich regions are purple proline-rich regions are green acidic regions are red
Fig. Phylogenetic analysis of 58 members of the AtWRKY family.
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Results
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Targets of AtWRKY6 regulation during plant senescence and pathogen defense
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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 defense- associated 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
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The Plant Journal
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En-1 transposon insertion
Figure 1. Identification of wrky6 knockout mutants
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Figure 2. WRKY6 overexpression lines.
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The Plant Journal
SAG:salicyilcacid glucoside
ELI:plant defence-Related gene
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The Plant Journal
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Figure 3. Repressor activity of WRKY6.
promotor GUS
promotor WRKY Knock out gene
Knock out
promotor GUS
promotor WRKY overexpression
overexepression
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Rhizobacterium
JA response
Ethylene response
Pathogen
SA JA responseNahG ethylene response
NPRnpr1
etr1
PDF1.2PRSDefensive compounds
ISR SAR
jar1
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The Plant Journal
Figure . Nuclear localization of endogenous AtWRKY6.
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The Plant Journal
Figure 4. Effect of WRKY6 overexpression on PR1 and NPR1.
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Table 1. cDNA-AFLP fragments and homologies to sequences in the Arabidopsis database
R:root transcripts.R1-R154P:aerieal part transcripts P1-P63
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Figure 5. Dependence of SIRK gene expression on WRKY6
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Figure 6. Specificity of the WRKY6-SIRK promoter interaction
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NecroticPathogeninfection
Systemic signal
SA NPR1 SARGeneexpression
EnhancedPathogenresistance
WRKY6?
SIRK