Isolation and Characterization of Tn5 Mutants of Pseudomonas Syringae Pv. Phaseolicola which Fail to Elicit a Hypersensitive Response

Abstract

When phytopathogenic bacteria are introduced into nonhost plants, they generally elicit a hypersensitive response (HR) which is thought to be involved in the resistance of the plant to the bacteria. The mechanism by which bacteria elicit an HR is unknown. Nonphytopathogenic bacteria do not elicit an HR, but it is unclear how the plant distinguishes between potential pathogens and other bacteria. In order to examine this problem we have isolated and begun to characterize bacterial mutants which fail to elicit an HR in a nonhost plant. For this purpose we are studying Pseudomonas syringae pv. phaseolicola which is the causative agent of halo blight disease of snap beans. P. s. phaseolicola elicits a hypersensitive response when a suspension of the bacteria is injected into leaves of Nicotiana tabacum.