RRC ID 27314
Author Koike S, Matsukura C, Takayama M, Asamizu E, Ezura H.
Title Suppression of γ-aminobutyric acid (GABA) transaminases induces prominent GABA accumulation, dwarfism and infertility in the tomato (Solanum lycopersicum L.).
Journal Plant Cell Physiol
Abstract Tomatoes accumulate γ-aminobutyric acid (GABA) at high levels in the immature fruits. GABA is rapidly converted to succinate during fruit ripening through the activities of GABA transaminase (GABA-T) and succinate semialdehyde dehydrogenase (SSADH). Although three genes encoding GABA-T and both pyruvate- and α-ketoglutarate-dependent GABA-T activities have been detected in tomato fruits, the mechanism underlying the GABA-T-mediated conversion of GABA has not been fully understood. In this work, we conducted loss-of-function analyses utilizing RNA interference (RNAi) transgenic plants with suppressed pyruvate- and glyoxylate-dependent GABA-T gene expression to clarify which GABA-T isoforms are essential for its function. The RNAi plants with suppressed SlGABA-T gene expression, particularly SlGABA-T1, showed severe dwarfism and infertility. SlGABA-T1 expression was inversely associated with GABA levels in the fruit at the red ripe stage. The GABA contents in 35S::SlGABA-T1(RNAi) lines were 1.3-2.0 times and 6.8-9.2 times higher in mature green and red ripe fruits, respectively, than the contents in wild-type fruits. In addition, SlGABA-T1 expression was strongly suppressed in the GABA-accumulating lines. These results indicate that pyruvate- and glyoxylate-dependent GABA-T is the essential isoform for GABA metabolism in tomato plants and that GABA-T1 primarily contributes to GABA reduction in the ripening fruits.
Volume 54(5)
Pages 793-807
Published 2013-5-1
DOI 10.1093/pcp/pct035
PII pct035
PMID 23435575
MeSH 4-Aminobutyrate Transaminase / metabolism* Amino Acids / metabolism Flowers / growth & development Fruit / growth & development Gene Expression Regulation, Plant Genes, Plant / genetics Glutamic Acid / metabolism Lycopersicon esculentum / enzymology* Lycopersicon esculentum / genetics Lycopersicon esculentum / growth & development* Metabolic Networks and Pathways / genetics Plant Infertility* Plant Leaves / enzymology Plant Leaves / genetics Plant Stems / metabolism Plants, Genetically Modified RNA Interference Suppression, Genetic* gamma-Aminobutyric Acid / metabolism*
IF 4.062
Times Cited 25
Tomato TOMJPF00001