ISOLATION OF THE TOMATO CF-9 GENE FOR RESISTANCE TO CLADOSPORIUM-FULVUM BY TRANSPOSON TAGGING

The tomato Cf-9 gene confers resistance to infection by races of the f ungus Cladosporium fulvum that carry the avirulence gene Avr9. The Cf- 9 gene was isolated by transposon tagging with the maize transposable element Dissociation, The DNA sequence of Cf-9 encodes a putative memb rane-anchored extracytoplasmic glycoprotein. The predicted protein sho ws homology to the receptor domain of several receptor-like protein ki nases in Arabidopsis, to antifungal polygalacturonase-inhibiting prote ins in plants, and to other members of the leucine-rich repeat family of proteins. This structure is consistent with that of a receptor that could bind Avr9 peptide and activate plant defense.