Browsing by Author "Bown, A. W"

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    PublicationOpen Access
    Gamma-hydroxybutyrate accumulates in green tea and soybean sprouts in response to oxygen deficiency
    (Canadian Science Publisher, 2003-10) Shelp, B. J; Allan, W. L; Peiris, C; Bown, A. W
    Gamma-hydroxybutyrate (GHB) is an illicit drug, which may be derived in plants from a stress-inducible metabolite known as gamma-aminobutyrate. Here, oxygen deficiency caused the accumulation of GHB in green tea and soybean sprouts (76 and 155 nmol g-1 fresh weight, respectively). These findings demonstrate that GHB levels are elevated in severely modified atmospheres, but they pose no risk to human health. Further work is required to assess the extent of this phenomenon.
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    PublicationOpen Access
    Overexpression of glutamate decarboxylase in transgenic tobacco plants deters feeding by phytophagous insect larvae
    (Kluwer Academic Publishers-Plenum Publishers, 2003-09) MacGregor, K. B; Shelp, B. J; Peiris, S; Bown, A. W
    Gamma-aminobutyrate (GABA) is a ubiquitous four-carbon, nonprotein 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 plantattached 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 localresistance mechanism.