Growth stage-based metabolite profiling of drought-tolerant transgenic rice under well-watered and deficit conditions

Abstract

Metabolite profiling of transgenic crops is useful when evaluating the intended and unintended effects of genetic modifications. Our study objective was to investigate variations in metabolites from drought-tolerant transgenic rice (Oryza sativa L.) that over-expresses AtCYP78A7, a gene encoding cytochrome P450 protein. Two transgenic Lines, '10B-5' and '18A-4', plus the wild-type 'Hwayoung', were cultivated under either well-watered or water-deficit conditions in a rainout shelter. Their shoots were collected at the tillering, heading, and ripening stages and polar extracts were subsequently analyzed by 1H-NMR and GC-MS. Principal component analysis revealed that the metabolite profiles could be clearly distinguished during those stages. Soil-water conditions also contributed to the variation in profiles. However, a marked discrimination of metabolites between transgenic and non-transgenic rice was apparent only under water-deficit conditions at the heading stage. This was mainly a result of differences in the sugar-related NMR profiles among genotypes. Our data suggested that the genetic contribution to metabolite profiles is constrained by growth stage and water status. In addition, sugar content is of great importance when separating metabolite profiles in shoots from rice plants that over-express AtCYP78A7.