Molecular and phenotypic characterization of vitamin C enriched rice

RB Broad1, JP Bonneau1, RP Hellens2, SM Roden2 and AAT Johnson1

  1. School of Biosciences, University of Melbourne, VIC 3010, Australia
  2. Centre for Tropical Crops and Biocommodities, Queensland University of Technology, Brisbane, QLD 4001, Australia

Human iron (Fe) deficiency is the most common nutritional deficiency worldwide affecting over 2 billion people. Enhancing the concentration and/or bioavailability of Fe in staple crops through conventional plant breeding or modern biotechnology, a process known as biofortification, represents a sustainable strategy for increasing human Fe intakes. Ascorbic acid (AsA), commonly known as vitamin C, is a strong enhancer of Fe bioavailability, however most staple crops have low AsA content. Notably, the active form of AsA is not detectable in polished and whole grain rice. Increasing AsA concentration in rice may therefore represent an effective and novel means of enhancing Fe bioavailability. Moreover, AsA is a major antioxidant in plants capable of preventing or minimizing the damaging effects of reactive oxygen species produced by abiotic stress. The major abiotic stresses limiting rice production worldwide such as drought, heat, and salinity are predicted to increase in frequency due to climate change. The need for crops with broad abiotic stress tolerance is thus critical for ensuring global food security. This project aims to characterize rice plants overexpressing the OsGGP gene, encoding the enzyme GDP-L-galactose phosphorylase, which regulates the rate limiting step in AsA biosynthesis. Preliminary analyses have found that T1 rice plants overexpressing OsGGP produce up to five-fold more AsA than wild-type rice in imbibed grain and that many lines have increased height compared to wild-type rice under normal growth conditions. Here we present a molecular and phenotypic characterization of the OsGGP overexpressing rice plants including transgene copy number, transgene expression analysis, and AsA concentration in vegetative tissues.