title: Accumulation of γ-aminobutyric acid in soybean by hypoxia germination and freeze-thawing incubation.
abstract: BACKGROUND
  γ-Aminobutyric acid (GABA) can be synthesised by the GABA shunt and polyamine degradation pathway in plants under hypoxia stress and lower temperature. The hypoxia germination freeze-thawing incubation was used as a new technique for accumulating more GABA in soybean.
  
  
  RESULTS
  Results showed that glutamate decarboxylase (GAD) and diamine oxidase (DAO) activity as well as GABA content increased during germination within 24 h under hypoxia. However, the contents of dry matters and protein decreased. When the hypoxia-treated sprouts were frozen at -18 °C for 12 h and thawed at 25 °C for 6 h, GABA content increased drastically to 7.21-fold of the non-frozen sprouts. Subsequently, the freeze-thawing sprouts were ground into homogenates and incubated. GABA content was 14.20-fold of the only-soaked seeds when homogenates was incubated at 45 °C for 80 min within 400 µmol L(-1) pyridoxine (VB6) (pH 6.5).
  
  
  CONCLUSIONS
  The hypoxia germination freeze-thawing incubation was an effective method for accumulating GABA in soybean. During incubation, DAO was more important for GABA formation in homogenate of germinated soybean compared with GAD.
authors.affiliation: College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, People's Republic of China.
authors.forename: Runqiang
authors.initials: R
authors.lastname: Yang
authors.affiliation: College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Feng
authors.affiliation: College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, People's Republic of China.
authors.forename: Shufang
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, People's Republic of China.
authors.forename: Nanjing
authors.initials: N
authors.lastname: Yu
authors.affiliation: College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, People's Republic of China.
authors.forename: Zhenxin
authors.initials: Z
authors.lastname: Gu
mesh_terms: D005615:Freezing; D018525:Germination / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D012639:Seeds / Q000254:growth & development / Q000378:metabolism; D013025:Glycine max / Q000502:physiology*; D013696:Temperature; D005680:gamma-Aminobutyric Acid / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid; D010100:Oxygen
keywords: GABA accumulation; freezing; germination; incubation; soybean; thawing