Enhanced levels of methionine and cysteine in transgenic alfalfa (Medicago sativaL.) plants over‐expressing theArabidopsiscystathionine γ‐synthase gene

Authors:
Publisher website
Google Scholar
Abstract
Summary: With the aim of increasing the methionine level in alfalfa (Medicago sativaL.) and thus improving its nutritional quality, we produced transgenic alfalfa plants that expressed theArabidopsiscystathionine γ‐synthase (AtCGS), the enzyme that controls the synthesis of the first intermediate metabolite in the methionine pathway. The AtCGScDNA was driven by theArabidopsisrubisco small subunit promoter to obtain expression in leaves. Thirty transgenic plants were examined for the transgene protein expression, and four lines with a high expression level were selected for further work. In these lines, the contents of methionine,S‐methylmethionine (SMM), and methionine incorporated into the water‐soluble protein fraction increased up to 32‐fold, 19‐fold, and 2.2‐fold, respectively, compared with that in wild‐type plants. Notably, in these four transgenic lines, the levels of free cysteine (the sulphur donor for methionine synthesis), glutathione (the cysteine storage and transport form), and protein‐bound cysteine increased up to 2.6‐fold, 5.5‐fold, and 2.3‐fold, respectively, relative to that in wild‐type plants. As the transgenic alfalfa plants over‐expressing AtCGS had significantly higher levels of both soluble and protein‐bound methionine and cysteine, they may represent a model and target system for improving the nutritional quality of forage crops.

This publication has 32 references indexed in Scilit: