Stress- and pathogen-induced Arabidopsis WRKY48 is a transcriptional activator that represses plant basal defense.
Plant WRKY transcription factors can function as either positive or negative regulators of plant basal disease resistance. Arabidopsis WRKY48 is induced by mechanical and/or osmotic stress due to infiltration and pathogen infection and, therefore, may play a role in plant defense responses. WRKY48 is localized to the nucleus, recognizes the TTGACC W-box sequence with a high affinity in vitro and functions in plant cells as a strong transcriptional activator. To determine the biological functions directly, we have isolated loss-of-function T-DNA insertion mutants and generated gain-of-function transgenic overexpression plants for WRKY48 in Arabidopsis. Growth of a virulent strain of the bacterial pathogen Pseudomonas syringae was decreased in the wrky48 T-DNA insertion mutants. The enhanced resistance of the loss-of-function mutants was associated with increased induction of salicylic acid-regulated PR1 by the bacterial pathogen. By contrast, transgenic WRKY48-overexpressing plants support enhanced growth of P. syringae and the enhanced susceptibility was associated with reduced expression of defense-related PR genes. These results suggest that WRKY48 is a negative regulator of PR gene expression and basal resistance to the bacterial pathogen P. syringae.
Xing
Deng-Hui
DH
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054, USA.
Lai
Zi-Bing
ZB
Zheng
Zu-Yu
ZY
Vinod
K M
KM
Fan
Bao-Fang
BF
Chen
Zhi-Xiang
ZX
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010935:Plant Diseases / Q000382:microbiology* / Q000517:prevention & control; D044224:Pseudomonas syringae / Q000472:pathogenicity*; D018749:RNA, Plant / Q000737:chemistry / Q000235:genetics; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020156:Salicylic Acid / Q000494:pharmacology; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D015342:DNA Probes; D004268:DNA-Binding Proteins; D018749:RNA, Plant; D012335:RNA, Ribosomal; D015534:Trans-Activators; D014157:Transcription Factors; D020156:Salicylic Acid