title: Soybean seeds expressing feedback-insensitive cystathionine γ-synthase exhibit a higher content of methionine.
abstract: Soybean seeds provide an excellent source of protein for human and livestock nutrition. However, their nutritional quality is hampered by a low concentration of the essential sulfur amino acid, methionine (Met). In order to study factors that regulate Met synthesis in soybean seeds, this study used the Met-insensitive form of Arabidopsis cystathionine γ-synthase (AtD-CGS), which is the first committed enzyme of Met biosynthesis. This gene was expressed under the control of a seed-specific promoter, legumin B4, and used to transform the soybean cultivar Zigongdongdou (ZD). In three transgenic lines that exhibited the highest expression level of AtD-CGS, the level of soluble Met increased significantly in developing green seeds (3.8-7-fold). These seeds also showed high levels of other amino acids. This phenomenon was more prominent in two transgenic lines, ZD24 and ZD91. The total Met content, which including Met incorporated into proteins, significantly increased in the mature dry seeds of these two transgenic lines by 1.8- and 2.3-fold, respectively. This elevation was accompanied by a higher content of other protein-incorporated amino acids, which led to significantly higher total protein content in the seeds of these two lines. However, in a third transgenic line, ZD01, the level of total Met and the level of other amino acids did not increase significantly in the mature dry seeds. This line also showed no significant change in protein levels. This suggests a positive connection between high Met content and the synthesis of other amino acids that enable the synthesis of more seed proteins.
authors.affiliation: The National Key Facility for Crop Gene Resources and Genetic Improvement, NFCRI, MOA Key Laboratory of Soybean Biology Beijing, Institute of Crop Science, The Chinese Academy of Agricultural Sciences, 12 Zhongguancun South Street, Beijing 100081, PR China.
authors.forename: Shikui
authors.initials: S
authors.lastname: Song
authors.forename: Wensheng
authors.initials: W
authors.lastname: Hou
authors.forename: Itamar
authors.initials: I
authors.lastname: Godo
authors.forename: Cunxiang
authors.initials: C
authors.lastname: Wu
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.forename: Ifat
authors.initials: I
authors.lastname: Matityahu
authors.forename: Yael
authors.initials: Y
authors.lastname: Hacham
authors.forename: Shi
authors.initials: S
authors.lastname: Sun
authors.forename: Tianfu
authors.initials: T
authors.lastname: Han
authors.forename: Rachel
authors.initials: R
authors.lastname: Amir
mesh_terms: D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008715:Methionine / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D013025:Glycine max / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D008715:Methionine; C022696:O-succinylhomoserine (thiol)-lyase; D019757:Carbon-Oxygen Lyases