RRC ID 33523
Author Takayama M, Koike S, Kusano M, Matsukura C, Saito K, Ariizumi T, Ezura H.
Title Tomato Glutamate Decarboxylase Genes SlGAD2 and SlGAD3 Play Key Roles in Regulating γ-Aminobutyric Acid Levels in Tomato (Solanum lycopersicum).
Journal Plant Cell Physiol
Abstract Tomato (Solanum lycopersicum) can accumulate relatively high levels of γ-aminobutyric acid (GABA) during fruit development. However, the molecular mechanism underlying GABA accumulation and its physiological function in tomato fruits remain elusive. We previously identified three tomato genes (SlGAD1, SlGAD2 and SlGAD3) encoding glutamate decarboxylase (GAD), likely the key enzyme for GABA biosynthesis in tomato fruits. In this study, we generated transgenic tomato plants in which each SlGAD was suppressed and those in which all three SlGADs were simultaneously suppressed. A significant decrease in GABA levels, i.e. 50-81% compared with wild-type (WT) levels, was observed in mature green (MG) fruits of the SlGAD2-suppressed lines, while a more drastic reduction (up to <10% of WT levels) was observed in the SlGAD3- and triple SlGAD-suppressed lines. These findings suggest that both SlGAD2 and SlGAD3 expression are crucial for GABA biosynthesis in tomato fruits. The importance of SlGAD3 expression was also confirmed by generating transgenic tomato plants that over-expressed SlGAD3. The MG and red fruits of the over-expressing transgenic lines contained higher levels of GABA (2.7- to 5.2-fold) than those of the WT. We also determined that strong down-regulation of the SlGADs had little effect on overall plant growth, fruit development or primary fruit metabolism under normal growth conditions.
Volume 56(8)
Pages 1533-45
Published 2015-8-1
DOI 10.1093/pcp/pcv075
PII pcv075
PMID 26009591
MeSH Down-Regulation Fruit / enzymology Fruit / genetics Fruit / physiology Gene Expression Regulation, Plant* Glutamate Decarboxylase / genetics* Glutamate Decarboxylase / metabolism Plant Proteins / genetics Plant Proteins / metabolism Plants, Genetically Modified Solanum lycopersicum / enzymology* Solanum lycopersicum / genetics Solanum lycopersicum / physiology gamma-Aminobutyric Acid / metabolism*
IF 4.062
Times Cited 18
Tomato TOMJPF00001