ARABIDOPSIS ENHANCED DISEASE SUSCEPTIBILITY MUTANTS EXHIBIT ENHANCED SUSCEPTIBILITY TO SEVERAL BACTERIAL PATHOGENS AND ALTERATIONS IN PR-1 GENE-EXPRESSION

To identify plant defense responses that limit pathogen attack, Arabid opsis eds mutants that exhibit enhanced disease susceptibility to the virulent bacterial pathogen Pseudomonas syringae pv maculicola ES4326 were previously identified. In this study, we show that each of four e ds mutants (eds5-1, eds6-1, eds7-1, and eds9-1) has a distinguishable phenotype with respect to the degree of susceptibility to a panel of b acterial phytopathogens and the ability to activate pathogenesis-relat ed PR-I gene expression after pathogen attack. None of the four eds mu tants exhibited observable defects in mounting a hypersensitive respon se. Although all four eds mutants were also capable of mounting a syst emic acquired resistance response, enhanced growth of P. s. maculicola ES4326 was still apparent in the secondarily infected leaves of three of the eds mutants. These data indicate that eds genes define a diver se set of previously unknown defense responses that affect resistance to virulent pathogens.