Accumulation mechanism of γ-aminobutyric acid in tomatoes (Solanum lycopersicum L.) under low O2 with and without CO2.
The storage of ripe tomatoes in low-O(2) conditions with and without CO(2) promotes γ-aminobutyric acid (GABA) accumulation. The activities of glutamate decarboxylase (GAD) and α-ketoglutarate-dependent GABA transaminase (GABA-TK) were higher and lower, respectively, following storage under hypoxic (2.4 or 3.5% O(2)) or adjusted aerobic (11% O(2)) conditions compared to the activities in air for 7 days at 25 °C. GAD activity was consistent with the expression level of mRNA for GAD. The GABA concentration in tomatoes stored under hypoxic conditions and adjusted aerobic conditions was 60-90% higher than that when they are stored in air on the same day. These results demonstrate that upregulation of GAD activity and downregulation of GABA-TK activity cause GABA accumulation in tomatoes stored under low-O(2) conditions. Meanwhile, the effect of CO(2) on GABA accumulation is probably minimal.
Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
Nobukazu
N
Mae
Yoshio
Y
Makino
Seiichi
S
Oshita
Yoshinori
Y
Kawagoe
Atsushi
A
Tanaka
Koh
K
Aoki
Atsushi
A
Kurabayashi
Takashi
T
Akihiro
Kazuhito
K
Akama
Satoshi
S
Koike
Mariko
M
Takayama
Chiaki
C
Matsukura
Hiroshi
H
Ezura
D000612:4-Aminobutyrate Transaminase / Q000378:metabolism; D002245:Carbon Dioxide / Q000008:administration & dosage*; D005519:Food Preservation / Q000379:methods*; D015870:Gene Expression / Q000187:drug effects; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D018551:Solanum lycopersicum / Q000378:metabolism*; D010100:Oxygen / Q000008:administration & dosage*; D012333:RNA, Messenger / Q000032:analysis; D005680:gamma-Aminobutyric Acid / Q000032:analysis / Q000378:metabolism*
D012333:RNA, Messenger; D002245:Carbon Dioxide; D005680:gamma-Aminobutyric Acid; D000612:4-Aminobutyrate Transaminase; D005968:Glutamate Decarboxylase; D010100:Oxygen