title: Stress- and pathogen-induced Arabidopsis WRKY48 is a transcriptional activator that represses plant basal defense.
abstract: 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.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907-2054, USA.
authors.forename: Deng-Hui
authors.initials: DH
authors.lastname: Xing
authors.forename: Zi-Bing
authors.initials: ZB
authors.lastname: Lai
authors.forename: Zu-Yu
authors.initials: ZY
authors.lastname: Zheng
authors.forename: K M
authors.initials: KM
authors.lastname: Vinod
authors.forename: Bao-Fang
authors.initials: BF
authors.lastname: Fan
authors.forename: Zhi-Xiang
authors.initials: ZX
authors.lastname: Chen
mesh_terms: 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*
chemical_list: 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