Myo-inositol Oxygenase Overexpression Rescues Vitamin C Deficient Arabidopsis (vtc) Mutants

Abstract

Biosynthesis of L-ascorbate (AsA) in plants is carried out by a complex metabolic network, which involves D-mannose/L-galactose, D-galacturonate, L-gulose, and myo-inositol as main precursors. Arabidopsis lines over-expressing enzymes in the myo-inositol pathway have elevated AsA, accumulate more biomass of both aerial and root tissues, and are tolerant to abiotic stresses as shown by manual and digital phenotyping. We crossed myo-inositol oxygenase (MIOX4) over- expressers with two low-vitamin C mutants (vtc1-1 and vtc2-1) encoding enzymes involved in D-mannose/L-galactose route. The purpose of developing these crosses was to test MIOX4’s ability to restore the low AsA phenotype in mutants, and to assess the contribution of individual biosynthetic pathways to abiotic stress tolerance. We used a powerful high-throughput phenotyping platform for detailed phenotypic characterization of the Arabidopsis crosses with visible, fluorescence, near-infrared and infrared sensors.