The present invention relates to isolated nucleic acid molecules encoding an autoinducer inactivation protein, wherein the encoded protein comprises an amino acid sequence selected from the group consisting of 104 HXHXDH 109 ~60aa~H 169 ~21aa~D 191 and 103 HXHXDH 108 ~72aa~H 180 ~21aa~D 202 , and to expression vectors and transformed plant and animal cells comprising the same. The proteins encoded by these nucleic acid molecules provide to a susceptible plant or animal increased resistance to a disease the virulence of which is regulated by autoinducers. Also provided are methods of increasing disease resistance in susceptible plants and animals.
