Enhanced transcription of the Arabidopsis disease resistance genes RPW8.1 and RPW8.2 via a salicylic acid-dependent amplification circuit is required for hypersensitive cell death.

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TitleEnhanced transcription of the Arabidopsis disease resistance genes RPW8.1 and RPW8.2 via a salicylic acid-dependent amplification circuit is required for hypersensitive cell death.
Publication TypeJournal Article
Year of Publication2003
AuthorsXiao, S, Brown, S, Patrick, E, Brearley, C, Turner, JG
JournalPlant Cell
Volume15
Issue1
Pagination33-45
Date Published2003 Jan
ISSN1040-4651
KeywordsApoptosis, Arabidopsis, Arabidopsis Proteins, Fungi, Hydrogen Peroxide, Immunity, Innate, Light, Plant Diseases, Plants, Genetically Modified, Salicylic Acid, Temperature, Transcription, Genetic
Abstract

The Arabidopsis disease resistance (R) genes RPW8.1 and RPW8.2 couple the recognition of powdery mildew pathogens of this plant with the subsequent induction of a localized necrosis, or hypersensitive response (HR). The HR restricts the spread of the infection and renders the plant resistant. One-third of Arabidopsis plants transformed with a genomic fragment containing RPW8.1 and RPW8.2 developed spontaneous HR-like lesions (SHL) in the absence of pathogens. We demonstrate that SHL occurs in transgenic lines that contain multiple copies of the transgene and express RPW8.1 and RPW8.2 at high levels. SHL is associated with salicylic acid (SA) accumulation, and at the site of the lesion, there is increased expression of RPW8.1, increased production of H(2)O(2), and increased expression of pathogenesis-related genes. These lesions are physiologically similar to the pathogen-induced HR mediated by RPW8.1 and RPW8.2. Significantly, environmental conditions that suppress SHL suppress the transcription of RPW8.1 and RPW8.2 and also suppress resistance to powdery mildews, even in transgenic lines containing RPW8.1 and RPW8.2 that normally do not express SHL. Furthermore, treatment with SA increases the transcription of RPW8.1 and RPW8.2, induces SHL, and enhances resistance to powdery mildews. We conclude that HR requires the transcription of RPW8.1 and RPW8.2, which is regulated independently of the pathogen by SA-dependent feedback amplification.

Alternate JournalPlant Cell
PubMed ID12509520
PubMed Central IDPMC143449