the wrky superfamily of plant transcription factors
TRANSCRIPT
The WRKY superfamily of plantThe WRKY superfamily of planttranscription factorstranscription 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 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.
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 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
The Plant Journal
En-1 transposon insertion
Figure 1. Identification of wrky6 knockout mutants
Figure 2. WRKY6 overexpression lines.
The Plant Journal
SAG:salicyilcacid glucoside
ELI:plant defence-Related gene
The Plant Journal
Figure 3. Repressor activity of WRKY6.
promotor GUS
promotor WRKY Knock out gene
Knock out
promotor GUS
promotor WRKY overexpression
overexepression
Rhizobacterium
JA response
Ethylene response
Pathogen
SA JA responseNahG ethylene response
NPRnpr1
etr1
PDF1.2PRSDefensive compounds
ISR SAR
jar1
The Plant Journal
Figure . Nuclear localization of endogenous AtWRKY6.
The Plant Journal
Figure 4. Effect of WRKY6 overexpression on PR1 and NPR1.
Table 1. cDNA-AFLP fragments and homologies to sequences in the Arabidopsis database
R:root transcripts.R1-R154P:aerieal part transcripts P1-P63
Figure 5. Dependence of SIRK gene expression on WRKY6
Figure 6. Specificity of the WRKY6-SIRK promoter interaction
NecroticPathogeninfection
Systemic signal
SA NPR1 SARGeneexpression
EnhancedPathogenresistance
WRKY6?
SIRK