Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 110717
Title Specific recognition of AVR4 and AVR9 results in distinct patterns of hypersensitive cell death in tomato, but similar patterns of defence-related gene expression
Author(s) Cai, X.; Takken, F.L.W.; Joosten, M.H.A.J.; Wit, P.J.G.M. De
Source Molecular Plant Pathology 2 (2001)2. - ISSN 1464-6722 - p. 77 - 86.
Department(s) Laboratory of Phytopathology
Publication type Refereed Article in a scientific journal
Publication year 2001
Abstract Hypersensitive cell death occurs in tomato seedlings that are derived from a cross between plants that express a resistance (Cf) gene against the pathogenic fungus Cladosporium fulvum and plants that contain the matching avirulence (Avr) gene originating from this fungus. The pattern of Cf-9/Avr9- and Cf-4/Avr4-induced necrosis in these F1 seedlings was found to differ significantly. Macroscopic observation revealed that in F1 tomato seedlings containing both Cf-9 and Avr9, numerous necrotic spots developed that were scattered over the entire cotyledon, while the midvein and primary veins remained unaffected. In seedlings containing both Cf-4 and Avr4, however, initially only one or a few necrotic spots developed on each cotyledon, in most cases in the midvein and occasionally in primary veins. Subsequently, these spots turned rapidly into lesions that enlarged along the midvein and primary veins, eventually causing the cotyledons to wilt and abscise. These observations were confirmed by detailed histological studies. Production of the AVR proteins in adult tomato plants carrying the matching Cf gene, employing potato virus X, resulted in similar patterns of necrosis. RNA gel blot analysis demonstrated that both Avr4 and Avr9, controlled by the CaMV 35S promoter, were highly expressed in seedlings already at one day post-emergence, indicating that the distinct necrotic patterns are not due to differences in Avr expression levels. We have analysed the expression of many genes involved in defence signalling pathways and the defence response itself, during the onset of the Cf/Avr-initiated hypersensitive response (HR). Although most of the genes were expressed stronger and faster in Cf-4/Avr4 seedlings than in Cf-9/Avr9 seedlings at the onset of HR, no significant qualitative differences in the expression of genes involved in downstream signalling were observed when Cf-4/Avr4- and Cf-9/Avr9-induced defence responses were compared.
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