Identification of AtWRKY75 as a transcriptional regulator in the defense response to Pcc through the screening of Arabidopsis activation-tagged lines
The necrotrophic pathogen Pectobacterium carotovorum ssp. carotovorum (Pcc) causes soft rot in a broad range of plant hosts. Approximately 60,000 independent seeds from Arabidopsis activation tagging lines were inoculated with Pcc and screened for resistant mutants. An Rpe1 (resistance protein to Pectobacterium 1) mutant, which had more resistance to Pcc than wild-type (WT) plants, was selected for further study. The T-DNA inserting locus in Rpe1 was located on the middle of chromosome V by flanking sequence analysis. Through expression analysis with several genes adjacent to the T-DNA tagging region, AtWRKY75 gene was highly up-regulated in the Rpe1 mutant compared to the WT plant. The up-regulation of AtWRKY75 gene was shown to be correlated on the induction of the PDF1.2, VSP1 and PR1 genes compared to the WT plant. AtWRKY75 over-expression lines exhibited reduced Pcc bacterial growth compared to WT. Taken together, our data suggest that AtWRKY75 should be a positive regulator in the JA- or SA-mediated defense signaling responses to Pcc.
KeywordsArabidopsis Activation tagging line AtWRKY75 Soft rot
Pectobacterium carotovora ssp. carotovora
Type II secretion system
Xanthomonas citri subsp. citri
We thank Prof. Lee J.S at Seoul National University for providing activation-tagged Arabidopsis seeds and Sunyoung Lee from the Rural Development Administration (RDA) for technical assistance. This work was supported by two grants (PJ007850 and PJ006775) from the RDA to Dr. Duk-Ju Hwang.
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