Manipulation of L-ascorbic Acid Biosynthesis Pathways in Solanum Lycopersicum

CRONJE C; GEORGE GM; KOSSMANN J; PIECKENSTAIN FL; BAUER R

St Louis

Simposio; International Symposium on Genetically-Modified Organisms; 2012

Ascorbate (AsA) plays a fundamental role in redox homeostasis in plants and animals, primarily by scavenging reactive oxygen species. Genes involved in AsA biosynthesis pathways, GDPmannose pyrophosphorylase (GMPase), arabinono 1,4- lactone oxidase (ALO) and myo-inositol oxygenase 2 (MIOX2), were independently expressed in Solanum lycopersicum (tomato) under control of the CaMV 35S promoter. An increase in 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. Plants with increased levels of ascorbic acid may alleviate oxidative stress caused by pathogen attack. This project aims to understand the role of plant antioxidant systems in defense response.