Overexpression of glutamate decarboxylase in transgenic tobacco plants deters feeding by phytophagous insect larvae.
Gamma-aminobutyrate (GABA) is a ubiquitous four-carbon, non-protein amino acid synthesized by glutamate decarboxylase. Previous research suggests that the endogenous synthesis of GABA, a naturally occurring inhibitory neurotransmitter at neuromuscular junctions, serves as a plant resistance mechanism against invertebrate pests. In this study, two homozygous transgenic tobacco lines constitutively overexpressing a single copy of a full-length chimeric glutamate decarboxylase cDNA and possessing enhanced capacity for GABA accumulation (GAD plants), a homozygous transgenic line lacking the gene insert, and wild-type tobacco were employed. Tobacco budworm larvae were presented with plant attached wild type and transgenic leaves for 4 hr in a feeding preference study. Larvae consumed six to twelve times more leaf tissue from wild-type plants than from GAD plants. These results suggest that leaf GABA accumulation, which is known to occur in response to insect larval walking and feeding, represents a rapidly deployed local resistance mechanism.
Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada L2S3A1.
Kennaway B
KB
MacGregor
Barry J
BJ
Shelp
Sriyani
S
Peiris
Alan W
AW
Bown
D000818:Animals; D001681:Biological Assay; D018076:DNA, Complementary; D005247:Feeding Behavior; D005786:Gene Expression Regulation; D005968:Glutamate Decarboxylase / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology*; D007300:Insect Control / Q000379:methods*; D007814:Larva; D009036:Moths / Q000502:physiology*; D010945:Plants, Edible / Q000737:chemistry; D030821:Plants, Genetically Modified; D014026:Nicotiana / Q000737:chemistry* / Q000235:genetics*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018076:DNA, Complementary; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase