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No Evidence for Binding Between Resistance Gene Product Cf-9 of Tomato and Avirulence Gene Product AVR9 of Cladosporium fulvum

July 2001 , Volume 14 , Number  7
Pages  867 - 876

Rianne Luderer , 1 Susana Rivas , 2 Thorsten Nürnberger , 3 Benedetta Mattei , 4 Henno W. Van den Hooven , 5 Renier A. L. Van der Hoorn , 1 Tina Romeis , 2 Josa-M. Wehrfritz , 2 Beatrix Blume , 3 Dirk Nennstiel , 3 Douwe Zuidema , 6 Jacques Vervoort , 5 Giulia De Lorenzo , 4 Jonathan D. G. Jones , 2 Pierre J. G. M. De Wit , 1 and Matthieu H. A. J. Joosten 1

1Laboratory of Phytopathology, Wageningen University, Binnenhaven 9, 6709 PD Wageningen, The Netherlands; 2The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich, NR4 7UH, U.K.; 3Institute of Plant Biochemistry, Weinberg 3, Halle/Saale, D-06120, Germany; 4Dipartimento di Biologia Vegetale, Università di Roma “La Sapienza,” Piazzale Aldo Moro 5, 00185, Roma, Italy; 5Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands; 6Laboratory of Virology, Wageningen University, Binnenhaven 11, 6709 PD Wageningen, The Netherlands

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Accepted 13 March 2001.

The gene-for-gene model postulates that for every gene determining resistance in the host plant, there is a corresponding gene conditioning avirulence in the pathogen. On the basis of this relationship, products of resistance (R) genes and matching avirulence (Avr) genes are predicted to interact. Here, we report on binding studies between the R gene product Cf-9 of tomato and the Avr gene product AVR9 of the pathogenic fungus Cladosporium fulvum. Because a high-affinity binding site (HABS) for AVR9 is present in tomato lines, with or without the Cf-9 resistance gene, as well as in other solanaceous plants, the Cf-9 protein was produced in COS and insect cells in order to perform binding studies in the absence of the HABS. Binding studies with radio-labeled AVR9 were performed with Cf-9-producing COS and insect cells and with membrane preparations of such cells. Furthermore, the Cf-9 gene was introduced in tobacco, which is known to be able to produce a functional Cf-9 protein. Binding of AVR9 to Cf-9 protein produced in tobacco was studied employing surface plasmon resonance and surface-enhanced laser desorption and ionization. Specific binding between Cf-9 and AVR9 was not detected with any of the procedures. The implications of this observation are discussed.

Additional keywords: elicitor, hypersensitive response, LRR, receptor.

© 2001 The American Phytopathological Society