Polyamine Oxidase and Its Possible Role in the Soybean-Fusarium virguliforme Interaction

Polyamines are small polycationic molecules found across kingdoms, and are important for cell maintenance. The breakdown of polyamines by polyamine oxidases produces smaller polyamines, amine products, and the free radical hydrogen peroxide. Hydrogen peroxide has been shown to be involved in the expression of plant defenses via cell signaling and cell wall strengthening, and also through its antimicrobial properties. Fusarium virguliforme is a soil borne fungal pathogen that causes sudden death syndrome (SDS) in soybean. The fungus infects only soybean roots and causes root necrosis. The fungus produces toxins that are implicated in foliar SDS development.  F. virguliforme has two polyamine oxidase genes, FvPO1 and FvPO2. FvPO1 shows minimal expression in spores and mycelia with increased expression following infection; while, FvPO2 is constitutively expressed. To investigate the role of this enzyme, knockout mutants for both FvPO1 and FvPO2 are created through homologous recombination. Currently, fvpo mutants are being investigated to understand if there is any role for this enzyme in the pathogenicity function of this serious soybean pathogen.