Modification of plant antioxidant status and its impact on pathogen defence

MUSARURWA HT; CRONJE C; KOSSMANN J; PIECKENSTAIN FL; BAUER R

Ciudad del Cabo

Congreso; Structural Biology in the Bioeconomy; 2012

Ascorbate (AsA) plays a fundamental role in redox homeostasis in plants, primarily by scavenging reactive oxygen species. Genes implicated in AsA biosynthesis pathways, GDPmannose pyrophosphorylase (GMPase), arabinono 1,4- lactone oxidase (ALO) and myo-inositol oxygenase 2 (MIOX2), were individually expressed in Solanum lycopersicum (tomato) under control of the CaMV 35S promoter. Enhanced GMPase activity was associated with increased AsA levels of up to 70% in leaves. Expression of ALO significantly pulled biosynthetic flux towards AsA while MIOX activity was strongly correlated with cell wall uronic acid levels. We are analyzing the consequences of AsA accumulation on plant antioxidant status and its impact on polyamine (PA)-mediated plant defenses against pathogens. Pathogenic microorganisms such as Botrytis cinerea and Sclerotinia sclerotiorum induce and take advantage of the accumulation of active oxygen species in their hosts, causing cell death. This project aims to (i) understand the role of plant antioxidant systems in defense response, and (ii) study the mechanisms of infection by pathogens.