Growing fuel and medicine: Advancing biofuels and plant-produced th...(f discovery at the interface and effor...)

Argelia Lorence, PhD Assistant Professor of Metabolic Engineering, Arkansas Bioscience Institute, Arkansas State University

Humans and several other animals are unable to synthesize vitamin C (ascorbate, AsA) and thus they are dependent on dietary sources, mainly fresh fruits and produce, to fulfill their requirements for this nutrient. In plants, AsA is one of the major carbohydrates and antioxidants that play a role in essential physiological processes such as photosynthesis, cell division, and stress tolerance. Although ascorbate as a chemical entity is an old molecule, the elucidation of how plants make this vitamin is a recent discovery. Four different pathways are known to be functional in plants, one of them proposed by our group involving myo-inositol (MI) as the main precursor. We have engineered elevated AsA levels in Arabidopsis by over-expressing MI oxygenase (MIOX4) and L-gulono-1,4-lactone oxidase (GLOase), enzymes involved in the MI pathway to AsA. One of our current objectives is to study the stress tolerance and growth of these high AsA lines. MIOX4 and GLOase over-expressers were challenged with various types of abiotics stresses and their growth and performance was compared to the one of wild type controls. MIOX4 or GLOase lines containing higher AsA content (2 to 3-fold), were more tolerant to salt, cold, heat, high light, and methyl viologen when compared to controls. They also displayed enhanced growth of both aerial and underground tissues. In addition, these lines exhibited tolerance to common environmental pollutants such as trichloroethylene, a chlorinated hydrocarbon, and pyrene, a model polycyclic aromatic hydrocarbon. These broad stress-tolerance responses are most likely due to the ability of AsA to detoxify reactive oxygen specie
'/>"/>