Phaseolotoxin: Environmental Conditions and Regulatory Mechanisms Involved in Its Synthesis

Phaseolotoxin is an antimetabolite toxin produced by diverse pathovars of Pseudomonas syringae which affects various plants, causing diseases of economic importance. Phaseolotoxin contributes to the systemic dissemination of the pathogen in the plant, therefore it is recognized as a major virulence factor. Genetic traits such as the Pht cluster, appear defining to the toxigenic strains phaseolotoxin producers. Extensive research has contributed to our knowledge concerning the regulation of phaseolotoxin revealing a complex regulatory network that involves processes at the transcriptional and posttranscriptional levels, in which specific and global regulators participate. Even more, significant advances in understanding how specific signals, including host metabolites, nutrient sources, and physical parameters such as the temperature, can affect phaseolotoxin production have been made. A general overview of the phaseolotoxin regulation, focusing on the chemical and physical cues, and regulatory pathways involved in the expression of this major virulence factor will be given in the present work.