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Wounding-Induced WRKY8 Is Involved in Basal Defense in Arabidopsis

Chen, Ligang, Zhang, Liping, Yu, Diqiu
Molecular plant-microbe interactions 2010 v.23 no.5 pp. 558-565
Arabidopsis thaliana, transcription factors, plant stress, cell nucleus, abscisic acid, hydrogen peroxide, plant damage, Botrytis cinerea, plant pathogenic fungi, Pseudomonas syringae, plant pathogenic bacteria, Aphidoidea, larvae, insect pests, plant pests, mutants, gene expression, transgenic plants, transfer DNA, disease resistance, gene expression regulation, salicylic acid, jasmonic acid, pathogenesis-related proteins
The WRKY family of plant transcription factors controls several types of plant stress responses. Arabidopsis WRKY8, localized to the nucleus, is mainly induced by abscissic acid, H2O2, wounding, Pseudomonas syringae and Botrytis cinerea infection, and aphid and maggot feeding. To determine its biological functions, we isolated loss-of-function T-DNA insertion mutants and generated gain-of-function overexpressing WRKY8 transgenic plants in Arabidopsis. Plants expressing the mutated WRKY8 gene showed increased resistance to P. syringae but slightly decreased resistance to B. cinerea. In contrast, transgenic plants overexpressing WRKY8 were more susceptible to P. syringae infection but more resistant to B. cinerea infection. The contrasting responses to the two pathogens were correlated with opposite effects on pathogen-induced expression of two genes; salicylic acid-regulated PATHOGENESIS-RELATED1 (PR1) and jasmonic acid-regulated PDF1.2. Therefore, our results suggest that WRKY8 is a negative regulator of basal resistance to P. syringae and positive regulator to B. cinerea.