Liping Zhang,1,2 and
1Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China; 2The Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
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Accepted 5 January 2010.
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.
© 2010 The American Phytopathological Society