Difference in gamma-aminobutyric acid content in vegetable soybean seeds
2005
Abe, T.(Yamagata Univ., Tsuruoka (Japan). Faculty of Agriculture) | Takeya, K.
Quantitative differences in free amino acids and gamma-aminobutyric acid (GABA) in the cotyledon of immature seeds harvested at 35 days after flowering (DAF) of six vegetative-type soybean (edamame) and two grain-type soybean cultivars were examined. The concentration of GABA varied greatly among cultivars. Immature seeds of two vegetative-type soybean cultivars, Shirayama-dadacha and Wase-shirayama, contained GABA at more than 50 mg/100g on a fresh weight (FW) basis. The free amino acid compositions differed between the cotyledon and hypocotyl (radicle-plumule axis) of the immature seeds of Shirayama-dadacha. The concentration of total free amino acids in the cotyledon of immature seeds increased until 30 DAF and then gradually decreased as the seeds matured up to 50 DAF. GABA content was highest at 15 DAF at over 50mg/100g FW, and it remained high until 35 DAF, after which it decreased until 50 DAF. Expression of glutamate decarboxylase (GAD) mRNA was examined by northern-blot analysis and was shown to be highest at 15-35 DAF and decreased until 50 DAF. The expression pattern was almost parallel with the GABA content during seed development.
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