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Comparing induction at an early and late step in signal transduction mediating indirect defence in Brassica oleracea.

Bruinsma M, Pang B, Mumm R, van Loon JJ, Dicke M - J. Exp. Bot. (2009)

Bottom Line: Ion channel-forming peptides represent a class of inducers that induce an early step in signal transduction.The parasitoid Cotesia glomerata was attracted to ALA-treated plants in a dose-dependent manner.This demonstrates that on a molar basis, ALA is a 20 times more potent inducer of indirect plant defence than JA, although this hormone has more commonly been used as a chemical inducer of plant defence.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH Wageningen, The Netherlands.

ABSTRACT
The induction of plant defences involves a sequence of steps along a signal transduction pathway, varying in time course. In this study, the effects of induction of an early and a later step in plant defence signal transduction on plant volatile emission and parasitoid attraction are compared. Ion channel-forming peptides represent a class of inducers that induce an early step in signal transduction. Alamethicin (ALA) is an ion channel-forming peptide mixture from the fungus Trichoderma viride that can induce volatile emission and increase endogenous levels of jasmonic acid (JA) and salicylic acid in plants. ALA was used to induce an early step in the defence response in Brussels sprouts plants, Brassica oleracea var. gemmifera, and to study the effect on volatile emission and on the behavioural response of parasitoids to volatile emission. The parasitoid Cotesia glomerata was attracted to ALA-treated plants in a dose-dependent manner. JA, produced through the octadecanoid pathway, activates a later step in induced plant defence signal transduction, and JA also induces volatiles that are attractive to parasitoids. Treatment with ALA and JA resulted in distinct volatile blends, and both blends differed from the volatile blends emitted by control plants. Even though JA treatment of Brussels sprouts plants resulted in higher levels of volatile emission, ALA-treated plants were as attractive to C. glomerata as JA-treated plants. This demonstrates that on a molar basis, ALA is a 20 times more potent inducer of indirect plant defence than JA, although this hormone has more commonly been used as a chemical inducer of plant defence.

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Effect of combinations of alamethicin and jasmonic acid compared with the effects of either inducer alone on behavioural responses of Cotesia glomerata parasitoids in the windtunnel. The numbers to the right of each bar represent the number of parasitoids making a choice, and the total number of parasitoids used in the windtunnel tests is indicated in parentheses (*P <0.05).
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fig3: Effect of combinations of alamethicin and jasmonic acid compared with the effects of either inducer alone on behavioural responses of Cotesia glomerata parasitoids in the windtunnel. The numbers to the right of each bar represent the number of parasitoids making a choice, and the total number of parasitoids used in the windtunnel tests is indicated in parentheses (*P <0.05).

Mentions: The preference of the wasps did not differ significantly between JA- and ALA-treated plants tested against each other at any combination of concentrations tested (binomial test, P >0.05; Fig. 3). At the low and intermediate concentrations of ALA (5 μg ml−1 and 20 μg ml−1) in combination with the low JA dose (0.05 mM), the ALA+JA-treated plants attracted significantly more wasps than the ALA-treated plants (P <0.05), but not more than the JA-treated plants (P >0.05; Fig. 3A, B). In combination with a high JA dose (0.5 mM), the wasps did not prefer the combination to the single treatments (Fig. 3D, E). However, at the high concentration of ALA (50 μg ml−1), the combination with 0.5 mM JA attracted significantly more wasps than JA alone (P <0.05; Fig. 3F). For the other combinations of JA and the highest concentration of ALA against single compound treatments, a tendency for attraction towards the combination of ALA and JA was observed (Fig. 3C, F).


Comparing induction at an early and late step in signal transduction mediating indirect defence in Brassica oleracea.

Bruinsma M, Pang B, Mumm R, van Loon JJ, Dicke M - J. Exp. Bot. (2009)

Effect of combinations of alamethicin and jasmonic acid compared with the effects of either inducer alone on behavioural responses of Cotesia glomerata parasitoids in the windtunnel. The numbers to the right of each bar represent the number of parasitoids making a choice, and the total number of parasitoids used in the windtunnel tests is indicated in parentheses (*P <0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2692015&req=5

fig3: Effect of combinations of alamethicin and jasmonic acid compared with the effects of either inducer alone on behavioural responses of Cotesia glomerata parasitoids in the windtunnel. The numbers to the right of each bar represent the number of parasitoids making a choice, and the total number of parasitoids used in the windtunnel tests is indicated in parentheses (*P <0.05).
Mentions: The preference of the wasps did not differ significantly between JA- and ALA-treated plants tested against each other at any combination of concentrations tested (binomial test, P >0.05; Fig. 3). At the low and intermediate concentrations of ALA (5 μg ml−1 and 20 μg ml−1) in combination with the low JA dose (0.05 mM), the ALA+JA-treated plants attracted significantly more wasps than the ALA-treated plants (P <0.05), but not more than the JA-treated plants (P >0.05; Fig. 3A, B). In combination with a high JA dose (0.5 mM), the wasps did not prefer the combination to the single treatments (Fig. 3D, E). However, at the high concentration of ALA (50 μg ml−1), the combination with 0.5 mM JA attracted significantly more wasps than JA alone (P <0.05; Fig. 3F). For the other combinations of JA and the highest concentration of ALA against single compound treatments, a tendency for attraction towards the combination of ALA and JA was observed (Fig. 3C, F).

Bottom Line: Ion channel-forming peptides represent a class of inducers that induce an early step in signal transduction.The parasitoid Cotesia glomerata was attracted to ALA-treated plants in a dose-dependent manner.This demonstrates that on a molar basis, ALA is a 20 times more potent inducer of indirect plant defence than JA, although this hormone has more commonly been used as a chemical inducer of plant defence.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH Wageningen, The Netherlands.

ABSTRACT
The induction of plant defences involves a sequence of steps along a signal transduction pathway, varying in time course. In this study, the effects of induction of an early and a later step in plant defence signal transduction on plant volatile emission and parasitoid attraction are compared. Ion channel-forming peptides represent a class of inducers that induce an early step in signal transduction. Alamethicin (ALA) is an ion channel-forming peptide mixture from the fungus Trichoderma viride that can induce volatile emission and increase endogenous levels of jasmonic acid (JA) and salicylic acid in plants. ALA was used to induce an early step in the defence response in Brussels sprouts plants, Brassica oleracea var. gemmifera, and to study the effect on volatile emission and on the behavioural response of parasitoids to volatile emission. The parasitoid Cotesia glomerata was attracted to ALA-treated plants in a dose-dependent manner. JA, produced through the octadecanoid pathway, activates a later step in induced plant defence signal transduction, and JA also induces volatiles that are attractive to parasitoids. Treatment with ALA and JA resulted in distinct volatile blends, and both blends differed from the volatile blends emitted by control plants. Even though JA treatment of Brussels sprouts plants resulted in higher levels of volatile emission, ALA-treated plants were as attractive to C. glomerata as JA-treated plants. This demonstrates that on a molar basis, ALA is a 20 times more potent inducer of indirect plant defence than JA, although this hormone has more commonly been used as a chemical inducer of plant defence.

Show MeSH