期刊
JOURNAL OF PLANT PHYSIOLOGY
卷 170, 期 3, 页码 338-345出版社
ELSEVIER GMBH, URBAN & FISCHER VERLAG
DOI: 10.1016/j.jplph.2012.10.018
关键词
Azuki bean; Cystathionine gamma-synthase; Methionine biosynthesis; Soybean; Transgenic plant
资金
- Japan Society for the Promotion of Science
- CREST, under the aegis of the Japan Science and Technology Agency
- Ministry of Agriculture, Forestry, and Fisheries of Japan (Genomics for Agricultural Innovation) [GMZ-1004]
- Fuji Foundation for Protein Research (Osaka, Japan)
Methionine (Met) is a sulfur-containing amino acid that is essential in mammals and whose low abundance limits the nutritional value of grain legumes. Cystathionine gamma-synthase (CGS) catalyzes the first committed step of Met biosynthesis, and the stability of its mRNA is autoregulated by the cytosolic concentration of S-adenosyl-L-methionine (SAM), a direct metabolite of Met. The mto 1-1 mutant of Arabidopsis thaliana harbors a mutation in the AtCGS1 gene that renders the mRNA resistant to SAM-dependent degradation and therefore results in the accumulation of free Met to high levels in young leaves. To manipulate Met biosynthesis in soybean and azuki bean, we introduced the AtCGS1 mto1-1 gene into the two grain legumes under the control of a seed-specific glycinin gene promoter. Transgenic seeds of both species accumulated soluble Met to levels at least twice those apparent in control seeds. However, the increase in free Met did not result in an increase in total Met content of the transgenic seeds. In transgenic azuki bean seeds, the amount of cystathionine, the direct product of CGS, was markedly increased whereas the total content of Met was significantly decreased compared with control seeds. Similar changes were not detected in soybean. Our data suggest that the regulation of Met biosynthesis differs between soybean and azuki bean, and that the expression of AtCGS1 mto1-1 differentially affects the metabolic stability of sulfur amino acids and their metabolites in the two grain legumes. (C) 2012 Elsevier GmbH. All rights reserved.
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