Elucidating the Effects of Higher Expression Level of Cystathionine γ-Synthase on Methionine Contents in Transgenic Arabidopsis, Soybean and Tobacco Seeds

Abstract

Plant seeds accumulate low contents of methionine in their seeds, limiting their nutritional values as a source of proteins. Previous conventional and molecular attempts to increase methionine levels in seeds by classical breeding, selection of mutants or creating ‘additional protein sinks’ for soluble methionine by expressing methionine-rich seed-storage proteins, have yielded only limited success. Here, we summarize our efforts to increase methionine contents in transgenic Arabidopsis, soybean and tobacco seeds by seed-specific expression of feedback-insensitive mutated forms of the Arabidopsis thaliana cystathionine γ-synthase (AtCGS), methionine main regulatory enzyme. Each of these species represents different plant families (Solanaceae, Brassicaceae and Fabaceae). The effects of the manipulations on the levels of soluble and total methionine and on the accumulation of storage compounds in these transgenic seeds are discussed.