title: γ-Aminobutyric Acid (GABA) Accumulation in Tea (Camellia sinensis L.) through the GABA Shunt and Polyamine Degradation Pathways under Anoxia.
abstract: γ-Aminobutyric acid (GABA) is an important bioactive component of tea (Camellia sinensis) providing various health benefits. We studied GABA accumulation via the GABA shunt and polyamine degradation pathways under anoxia in tea leaves. Anoxia caused a ∼20-fold increment in GABA concentration, relative to fresh tea leaves. This increment was due to the increase of glutamate decarboxylase and diamine oxidase activities. Genes involved in GABA formation, such as CsGAD1 and CsGAD2, were significantly up-regulated by anoxia. The concentrations of putrescine and spermine, two substrates for GABA production, were also increased by anoxia. Treating tea leaves with aminoguanidine completely inhibited diamine oxidase activity during anoxia, but the concentration of GABA decreased by only ∼25%. We infer that about one-fourth of GABA formed in tea leaves under anoxia comes from the polyamine degradation pathway, opening the possibility of producing GABA tea based through the regulation of metabolism.
authors.affiliation: College of Horticulture, Nanjing Agricultural University , Nanjing 210095, People's Republic of China.
authors.forename: Jieren
authors.initials: J
authors.lastname: Liao
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University , Nanjing 211800, People's Republic of China.
authors.forename: Xiayuan
authors.initials: X
authors.lastname: Wu
authors.affiliation: Suzhou Jiahe Foods Industry Company Ltd. , Wujiang, Suzhou 215222, People's Republic of China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Xing
authors.affiliation: College of Horticulture, Nanjing Agricultural University , Nanjing 210095, People's Republic of China.
authors.forename: Qinghui
authors.initials: Q
authors.lastname: Li
authors.affiliation: College of Horticulture, Nanjing Agricultural University , Nanjing 210095, People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Duan
authors.affiliation: College of Horticulture, Nanjing Agricultural University , Nanjing 210095, People's Republic of China.
authors.forename: Wanping
authors.initials: W
authors.lastname: Fang
authors.affiliation: College of Horticulture, Nanjing Agricultural University , Nanjing 210095, People's Republic of China.
authors.forename: Xujun
authors.identifier: http://orcid.org/0000-0001-8932-4324
authors.initials: X
authors.lastname: Zhu
keywords: GABA shunt; anoxic treatment; polyamine degradation; tea; γ-aminobutyric acid