Gene cluster of XXXX . "phaseolicola" controls pathogenicity of bean plants and hypersensitivity of nonhost plants.

@entity286 @entity11297 @entity523 @entity3437 @entity1460 @entity11314
Loss of the ability of @entity3437 . "phaseolicola" NPS3121 to elicit a hypersensitive response on @entity286 and other nonhost plants was associated with loss of pathogenicity on the susceptible host bean. Eight independent, prototrophic transposon Tn5 insertion mutants which had lost the ability to elicit a hypersensitive response on @entity286 plants were identified. Six of these mutants no longer produced disease lesions on primary leaves of the susceptible bean cultivar Red Kidney and failed to elicit a hypersensitive response on the resistant bean cultivar Red Mexican and on the nonhost plants @entity523 , @entity11314 , and @entity1460 . The two remaining mutants had reduced pathogenicity on Red @entity11297 and elicited variable hypersensitive responses on the other plants tested. Southern blot analysis indicated that each mutant carried a single independent Tn5 insertion in one of three EcoRI fragments of about 17, 7, and 5 kilobases. Marker exchange mutagenesis further supported the conclusion that the pleiotropic mutant phenotype was not associated with multiple Tn5 insertions. A genomic library of the wild-type strain was constructed in the cosmid vector pLAFR3. A recombinant plasmid, designated pPL6, that carried @entity3437 . "phaseolicola" genomic sequences was identified by colony hybridization. This plasmid restored the wild-type phenotype to all but one mutant, suggesting that genes affected by the insertions were clustered. Structural analysis of pPL6 and the wild-type genome indicated that the 17- and 5-kilobase EcoRI fragments were contiguous in the strain NPS3121 genome.
