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MacGregor, Kennaway B.; Shelp, Barry J.; Peiris, Sriyani; Bown, Alan W.

doi:10.1023/a:1025650914947

Cited by 59 publications

(16 citation statements)

References 7 publications

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“…The GABA-induced degradation of OC8-HSL would, however, constitute part of the plant defense mechanisms against bacterial infection. Such a role has already been assigned to GABA during infestation or feeding by invertebrate pests, whose neuromuscular junctions are very sensitive to GABA (21,24). The transgenic GAD and GAD⌬C tobacco lines used in this work were previously described as more resistant than wild-type tobacco to infestation by the northern root-knot nematode (21).…”

Section: Discussionmentioning

confidence: 89%

GABA controls the level of quorum-sensing signal in Agrobacterium tumefaciens

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Haudecoeur

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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The concentration of GABA increases rapidly in wounded plant tissues, but the implication of this GABA pulse for plant-bacteria interactions is not known. Here we reveal that GABA stimulated the inactivation of the N-(3-oxooctanoyl)homoserine lactone (OC8-HSL) quorum-sensing signal (or ''quormone'') by the Agrobacterium lactonase AttM. GABA induced the expression of the attKLM operon, which was correlated to a decrease in OC8-HSL concentration in Agrobacterium tumefaciens cultures. The Agrobacterium GABA transporter Bra was required for this GABA-signaling pathway. Furthermore, transgenic tobacco plants with elevated GABA levels were less sensitive to A. tumefaciens C58 infection than were wild-type plants. These findings indicate that plant GABA may modulate quorum sensing in A. tumefaciens, thereby affecting its virulence on plants. Whereas GABA is an essential cell-to-cell signal in eukaryotes, here we provide evidence of GABA acting as a signal between eukaryotes and pathogenic bacteria. The GABA signal represents a potential target for the development of a strategy to control the virulence of bacterial pathogens.phytopathology ͉ plant signal ͉ lactonase ͉ quorum quenching

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Section: Discussionmentioning

confidence: 89%

GABA controls the level of quorum-sensing signal in Agrobacterium tumefaciens

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Rosen

Haudecoeur

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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“…This mutant has not been used and characterized in the context of herbivory. Previous studies observed that increased concentrations of GABA can affect insect’s development (Ramputh and Bown, 1996; MacGregor et al, 2003; Bown et al, 2006; Scholz et al, 2015). We used the pop2-5 mutant to further evaluate the effect of high endogenous GABA concentration in planta on the herbivorous larvae of Spodoptera littoralis in a feeding assay ( Figure 2 ).…”

Section: Resultsmentioning

confidence: 98%

Evidence for GABA-Induced Systemic GABA Accumulation in Arabidopsis upon Wounding

et al. 2017

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The non-proteinogenic amino acid γ-aminobutyric acid (GABA) is present in all plant species analyzed so far. Its synthesis is stimulated by either acidic conditions occurring after tissue disruption or higher cytosolic calcium level. In mammals, GABA acts as inhibitory neurotransmitter but its function in plants is still not well understood. Besides its involvement in abiotic stress resistance, GABA has a role in the jasmonate-independent defense against invertebrate pests. While the biochemical basis for GABA accumulation in wounded leaves is obvious, the underlying mechanisms for wounding-induced GABA accumulation in systemic leaves remained unclear. Here, the Arabidopsis thaliana knock-out mutant lines pop2-5, unable to degrade GABA, and tpc1-2, lacking a wounding-induced systemic cytosolic calcium elevation, were employed for a comprehensive investigation of systemic GABA accumulation. A wounding-induced systemic GABA accumulation was detected in tpc1-2 plants demonstrating that an increased calcium level was not involved. Similarly, after both mechanical wounding and Spodoptera littoralis feeding, GABA accumulation in pop2-5 plants was significantly higher in local and systemic leaves, compared to wild-type plants. Consequently, larvae feeding on these GABA-enriched mutant plants grew significantly less. Upon exogenous application of a D2-labeled GABA to wounded leaves of pop2-5 plants, its uptake but no translocation to unwounded leaves was detected. In contrast, an accumulation of endogenous GABA was observed in vascular connected systemic leaves. These results suggest that the systemic accumulation of GABA upon wounding does not depend on the translocation of GABA or on an increase in cytosolic calcium.

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“…Due to the finding that higher GABA levels can affect insects (Ramputh and Bown, 1996 ; MacGregor et al, 2003 ; Bown et al, 2006 ) the influence of different endogenous GABA concentration in planta was investigated in parallel in an insect herbivore feeding assay. In contrast to former experiments (MacGregor et al, 2003 ; Bown et al, 2006 ), we did not look for feeding preferences but for insect performance on different mutant lines. Therefore, we carried out a bio-assay employing the three plant lines, wild type, g ad1/2 , and g ad1/2 x pop2-5 plants (Figure S4 ), and herbivorous larvae of the generalist lepidopteran species Spodoptera littoralis .…”

Section: Resultsmentioning

confidence: 99%

“…(ii) Leaf tissues of soybean ( Glycine max ) and tobacco ( Nicotiana tabacum ) that were only slightly wounded by crawling insect species ( C. rosaceana and the tobacco budworm, Heliothis virescens , respectively) showed a GABA accumulation up to 4- to 12-fold within 5–10 min (Bown et al, 2002 ). (iii) Transgenic N. tabacum plants with elevated GABA levels due to constitutive transgenic expression of a GAD enzyme were more resistant to both H. virescens larvae and Meloidogyne hapla , the root-knot nematode (MacGregor et al, 2003 ; McLean et al, 2003 ; Bown et al, 2006 ).…”

Section: Introductionmentioning

confidence: 99%

Insect Herbivory-Elicited GABA Accumulation in Plants is a Wound-Induced, Direct, Systemic, and Jasmonate-Independent Defense Response

et al. 2015

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The non-proteinogenic amino acid γ-aminobutyric acid (GABA) is present in all organisms analyzed so far. In invertebrates GABA acts as a neurotransmitter; in plants different functions are under discussion. Among others, its involvement in abiotic stress reactions and as a defensive compound against feeding insects is suggested. GABA is synthesized from glutamate by glutamate decarboxylases and degraded by GABA-transaminases. Here, in Arabidopsis thaliana, gad1/2 double mutants showing reduced GABA concentrations as well as GABA-enriched triple mutants (gad1/2 x pop2-5) were generated and employed for a systematic study of GABA induction, accumulation and related effects in Arabidopsis leaves upon herbivory. The results demonstrate that GABA accumulation is stimulated by insect feeding-like wounding by a robotic caterpillar, MecWorm, as well as by real insect (Spodoptera littoralis) herbivory. Higher GABA levels in both plant tissue and artificial dietary supplements in turn affect the performance of feeding larvae. GABA enrichment occurs not only in the challenged but also in adjacent leaf. This induced response is neither dependent on herbivore defense-related phytohormones, jasmonates, nor is jasmonate induction dependent on the presence of GABA. Thus, in Arabidopsis the rapid accumulation of GABA very likely represents a general, direct and systemic defense reaction against insect herbivores.

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Cited by 59 publications

References 7 publications

GABA controls the level of quorum-sensing signal in Agrobacterium tumefaciens

GABA controls the level of quorum-sensing signal in Agrobacterium tumefaciens

Evidence for GABA-Induced Systemic GABA Accumulation in Arabidopsis upon Wounding

Insect Herbivory-Elicited GABA Accumulation in Plants is a Wound-Induced, Direct, Systemic, and Jasmonate-Independent Defense Response

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