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

Abstract

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.

Retracted: The Cf-9 Disease Resistance Protein Is Present in an ∼420-Kilodalton Heteromultimeric Membrane-Associated Complex at One Molecule per Complex

“…This was higher than expected for the monomeric form of Cf-9:myc, strongly suggesting that Cf-9 is part of a protein complex in the membrane. No cross-reacting band was observed when extracts from untransformed Petit Havana plants were used (data not shown) (Luderer et al, 2001). To further confirm the specificity of the cross-reacting bands in Figure 4A, eluted fractions 23 to 25 from the gel filtration column containing Cf-9:myc were pooled and subjected to immunoprecipitation.…”

The Receptor for the Fungal Elicitor Ethylene-Inducing Xylanase Is a Member of a Resistance-Like Gene Family in Tomato

“…Furthermore, Luderer et al (2001) demonstrated that COS-7 cells, transfected with the Cf-9 gene, presented the protein on the plasma membrane. We showed that expression of LeEix2 in the COS-7 cells enables the binding of EIX in the absence of other plant proteins and hence indicates direct binding between the EIX and the LeEix2 protein.…”

“…Similarly, interaction between the cytoplasmic receptor Pi-ta and the corresponding AVR-Pita is required to induce resistance response (Jia et al, 2000). While these interactions are crucial for plant defense induction, the Avr9 elicitor exhibits high affinity binding to plasma membranes isolated from both resistant and susceptible tomato (Lycopersicon esculentum) cultivars (Kooman-Gersmann et al, 1996;Luderer et al, 2001).…”

EHD2 inhibits signaling of Leucine rich repeat receptor-like proteins

“…It was also demonstrated in several cases that Cf9 does not directly bind Avr9. 21 Despite these facts, it would seem that Cf receptors may undergo endocytosis, given that they possess a YXXφ domain and are capable of having their activity modulated by the endocytic protein EHD2.…”