PT  - JOURNAL ARTICLE
AU  - Thomas, C M
AU  - Jones, D A
AU  - Parniske, M
AU  - Harrison, K
AU  - Balint-Kurti, P J
AU  - Hatzixanthis, K
AU  - Jones, J D
TI  - Characterization of the tomato Cf-4 gene for resistance to Cladosporium fulvum identifies sequences that determine recognitional specificity in Cf-4 and Cf-9.
AID  - 10.1105/tpc.9.12.2209
DP  - 1997 Dec 01
TA  - The Plant Cell
PG  - 2209--2224
VI  - 9
IP  - 12
4099  - http://www.plantcell.org/content/9/12/2209.short
4100  - http://www.plantcell.org/content/9/12/2209.full
SO  - Plant Cell1997 Dec 01; 9
AB  - In many interactions between plants and their pathogens, resistance to infection is specified by plant resistance (R) genes and corresponding pathogen avirulence (Avr) genes. In tomato, the Cf-4 and Cf-9 resistance genes map to the same location but confer resistance to Cladosporium fulvum through recognition of different avirulence determinants (AVR4 and AVR9) by a molecular mechanism that has yet to be determined. Here, we describe the cloning and characterization of Cf-4, which also encodes a membrane-anchored extracellular glycoprotein. Cf-4 contains 25 leucine-rich repeats, which is two fewer than Cf-9. The proteins have > 91% identical amino acids. DNA sequence comparison suggests that Cf-4 and Cf-9 are derived from a common progenitor sequence. Amino acid differences distinguishing Cf-4 and Cf-9 are confined to their N termini, delimiting a region that determines the recognitional specificity of ligand binding. The majority of these differences are in residues interstitial to those of the leucine-rich repeat consensus motif. Many of these residues are predicted to form a solvent-exposed surface that can interact with the cognate ligand. Both Cf-4 and Cf-9 are located within a 36-kb region comprising five tandemly duplicated homologous genes. These results provide further insight into the molecular basis of pathogen perception by plants and the organization of complex R gene loci.