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Differences in volatile profiles of turnip plants subjected to single and dual herbivory above- and belowground.

Pierre PS, Jansen JJ, Hordijk CA, van Dam NM, Cortesero AM, Dugravot S - J. Chem. Ecol. (2011)

Bottom Line: Dual infestation resulted in several HIPVs that were present in both isolated infestation types.It remains to be determined whether or not these minor quantitative variations, within the background of more commonly induced odors, are involved in the reduced attraction of the root feeder's parasitoid.The mechanisms involved in the specific modification of the odor blends emitted by dual infested turnip plants are discussed in the light of interferences between biosynthetic pathways linked to plant responses to shoot or root herbivory.

View Article: PubMed Central - PubMed

Affiliation: UMR 1099 BiO3P, University of Rennes 1, INRA, Agrocampus Ouest, 263 avenue du Général Leclerc, 35042, Rennes Cedex, France. pierreprisca@yahoo.fr

ABSTRACT
Plants attacked by herbivorous insects emit volatile organic compounds that are used by natural enemies to locate their host or prey. The composition of the blend is often complex and specific. It may vary qualitatively and quantitatively according to plant and herbivore species, thus providing specific information for carnivorous arthropods. Most studies have focused on simple interactions that involve one species per trophic level, and typically have investigated the aboveground parts of plants. These investigations need to be extended to more complex networks that involve multiple herbivory above- and belowground. A previous study examined whether the presence of the leaf herbivore Pieris brassicae on turnip plants (Brassica rapa subsp. rapa) influences the response of Trybliographa rapae, a specialist parasitoid of the root feeder Delia radicum. It showed that the parasitoid was not attracted by volatiles emitted by plants under simultaneous attack. Here, we analyzed differences in the herbivore induced plant volatile (HIPV) mixtures that emanate from such infested plants by using Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA). This multivariate model focuses on the differences between odor blends, and highlights the relative importance of each compound in an HIPV blend. Dual infestation resulted in several HIPVs that were present in both isolated infestation types. However, HIPVs collected from simultaneously infested plants were not the simple combination of volatiles from isolated forms of above- and belowground herbivory. Only a few specific compounds characterized the odor blend of each type of damaged plant. Indeed, some compounds were specifically induced by root herbivory (4-methyltridecane and salicylaldehyde) or shoot herbivory (methylsalicylate), whereas hexylacetate, a green leaf volatile, was specifically induced after dual herbivory. It remains to be determined whether or not these minor quantitative variations, within the background of more commonly induced odors, are involved in the reduced attraction of the root feeder's parasitoid. The mechanisms involved in the specific modification of the odor blends emitted by dual infested turnip plants are discussed in the light of interferences between biosynthetic pathways linked to plant responses to shoot or root herbivory.

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Two dimensional bubble plot representation of volatiles emitted after different forms of herbivore infestations in Brassica rapa subsp. rapa plants: discriminate functions of root herbivory by Delia radicum larvae (D) and leaf herbivory by Pieris brassicae caterpillars (P) plotted against each other. Numbers correspond to compounds listed in Table 1. The size of each bubble representing a volatile corresponds to the weight vector value of that volatile for the dual herbivory treatment, i.e., herbivory by Delia radicum larvae and Pieris brassicae caterpillars (DP). The color shows if the volatile increases (filled) or decreases (open) in the DP treatment. The three arrows indicate examples of compounds given in the text. The table below presents the number of latent variables (LVs) prescribed by cross-validation and the P-values for the significance (P ≤ 0.050) of the system-wide effect brought about by each form of herbivory
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Fig1: Two dimensional bubble plot representation of volatiles emitted after different forms of herbivore infestations in Brassica rapa subsp. rapa plants: discriminate functions of root herbivory by Delia radicum larvae (D) and leaf herbivory by Pieris brassicae caterpillars (P) plotted against each other. Numbers correspond to compounds listed in Table 1. The size of each bubble representing a volatile corresponds to the weight vector value of that volatile for the dual herbivory treatment, i.e., herbivory by Delia radicum larvae and Pieris brassicae caterpillars (DP). The color shows if the volatile increases (filled) or decreases (open) in the DP treatment. The three arrows indicate examples of compounds given in the text. The table below presents the number of latent variables (LVs) prescribed by cross-validation and the P-values for the significance (P ≤ 0.050) of the system-wide effect brought about by each form of herbivory

Mentions: The fitted OPLS-DA models showed that the effect of all three herbivore treatments on the HIPV emissions can be described by simple low-dimensional multivariate models. The cross-validation yielded a single latent variable for all three to significantly distinguish the volatile blends emitted by turnip plants (Table in Fig. 1). The comparison of these three separate OPLS-DA models for communalities and differences caused by different forms and levels of herbivory was done by plotting the discriminate functions of root herbivory by D. radicum (D) and leaf herbivory by P. brassicae (P) against each other (Fig. 1). Increased levels of a compound in D or P are indicated by a positive weight vector value on the respective axis, while reduced levels are shown by a negative value. The size of each bubble corresponds to the weight vector value of a volatile for the dual herbivory treatment (DP). The maximal bubble size corresponds to (3E)-4,8-dimethyl-1,3,7-nonatriene DMNT (2), which then is related to the highest vector value for DP (0.394) and to the most significant difference from the vector value for the control (P = 0.004). The absolute minimal bubble size is associated with heptadecene (29), which has the lowest absolute vector value for DP (0.002) and the least significant difference from the vector value for the control (P = 0.595). The bubble size of hexylacetate (9) represents a threshold of significance (weight vector value = 0.300; P = 0.044) of weight vector values associated with DP.Fig. 1


Differences in volatile profiles of turnip plants subjected to single and dual herbivory above- and belowground.

Pierre PS, Jansen JJ, Hordijk CA, van Dam NM, Cortesero AM, Dugravot S - J. Chem. Ecol. (2011)

Two dimensional bubble plot representation of volatiles emitted after different forms of herbivore infestations in Brassica rapa subsp. rapa plants: discriminate functions of root herbivory by Delia radicum larvae (D) and leaf herbivory by Pieris brassicae caterpillars (P) plotted against each other. Numbers correspond to compounds listed in Table 1. The size of each bubble representing a volatile corresponds to the weight vector value of that volatile for the dual herbivory treatment, i.e., herbivory by Delia radicum larvae and Pieris brassicae caterpillars (DP). The color shows if the volatile increases (filled) or decreases (open) in the DP treatment. The three arrows indicate examples of compounds given in the text. The table below presents the number of latent variables (LVs) prescribed by cross-validation and the P-values for the significance (P ≤ 0.050) of the system-wide effect brought about by each form of herbivory
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3197925&req=5

Fig1: Two dimensional bubble plot representation of volatiles emitted after different forms of herbivore infestations in Brassica rapa subsp. rapa plants: discriminate functions of root herbivory by Delia radicum larvae (D) and leaf herbivory by Pieris brassicae caterpillars (P) plotted against each other. Numbers correspond to compounds listed in Table 1. The size of each bubble representing a volatile corresponds to the weight vector value of that volatile for the dual herbivory treatment, i.e., herbivory by Delia radicum larvae and Pieris brassicae caterpillars (DP). The color shows if the volatile increases (filled) or decreases (open) in the DP treatment. The three arrows indicate examples of compounds given in the text. The table below presents the number of latent variables (LVs) prescribed by cross-validation and the P-values for the significance (P ≤ 0.050) of the system-wide effect brought about by each form of herbivory
Mentions: The fitted OPLS-DA models showed that the effect of all three herbivore treatments on the HIPV emissions can be described by simple low-dimensional multivariate models. The cross-validation yielded a single latent variable for all three to significantly distinguish the volatile blends emitted by turnip plants (Table in Fig. 1). The comparison of these three separate OPLS-DA models for communalities and differences caused by different forms and levels of herbivory was done by plotting the discriminate functions of root herbivory by D. radicum (D) and leaf herbivory by P. brassicae (P) against each other (Fig. 1). Increased levels of a compound in D or P are indicated by a positive weight vector value on the respective axis, while reduced levels are shown by a negative value. The size of each bubble corresponds to the weight vector value of a volatile for the dual herbivory treatment (DP). The maximal bubble size corresponds to (3E)-4,8-dimethyl-1,3,7-nonatriene DMNT (2), which then is related to the highest vector value for DP (0.394) and to the most significant difference from the vector value for the control (P = 0.004). The absolute minimal bubble size is associated with heptadecene (29), which has the lowest absolute vector value for DP (0.002) and the least significant difference from the vector value for the control (P = 0.595). The bubble size of hexylacetate (9) represents a threshold of significance (weight vector value = 0.300; P = 0.044) of weight vector values associated with DP.Fig. 1

Bottom Line: Dual infestation resulted in several HIPVs that were present in both isolated infestation types.It remains to be determined whether or not these minor quantitative variations, within the background of more commonly induced odors, are involved in the reduced attraction of the root feeder's parasitoid.The mechanisms involved in the specific modification of the odor blends emitted by dual infested turnip plants are discussed in the light of interferences between biosynthetic pathways linked to plant responses to shoot or root herbivory.

View Article: PubMed Central - PubMed

Affiliation: UMR 1099 BiO3P, University of Rennes 1, INRA, Agrocampus Ouest, 263 avenue du Général Leclerc, 35042, Rennes Cedex, France. pierreprisca@yahoo.fr

ABSTRACT
Plants attacked by herbivorous insects emit volatile organic compounds that are used by natural enemies to locate their host or prey. The composition of the blend is often complex and specific. It may vary qualitatively and quantitatively according to plant and herbivore species, thus providing specific information for carnivorous arthropods. Most studies have focused on simple interactions that involve one species per trophic level, and typically have investigated the aboveground parts of plants. These investigations need to be extended to more complex networks that involve multiple herbivory above- and belowground. A previous study examined whether the presence of the leaf herbivore Pieris brassicae on turnip plants (Brassica rapa subsp. rapa) influences the response of Trybliographa rapae, a specialist parasitoid of the root feeder Delia radicum. It showed that the parasitoid was not attracted by volatiles emitted by plants under simultaneous attack. Here, we analyzed differences in the herbivore induced plant volatile (HIPV) mixtures that emanate from such infested plants by using Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA). This multivariate model focuses on the differences between odor blends, and highlights the relative importance of each compound in an HIPV blend. Dual infestation resulted in several HIPVs that were present in both isolated infestation types. However, HIPVs collected from simultaneously infested plants were not the simple combination of volatiles from isolated forms of above- and belowground herbivory. Only a few specific compounds characterized the odor blend of each type of damaged plant. Indeed, some compounds were specifically induced by root herbivory (4-methyltridecane and salicylaldehyde) or shoot herbivory (methylsalicylate), whereas hexylacetate, a green leaf volatile, was specifically induced after dual herbivory. It remains to be determined whether or not these minor quantitative variations, within the background of more commonly induced odors, are involved in the reduced attraction of the root feeder's parasitoid. The mechanisms involved in the specific modification of the odor blends emitted by dual infested turnip plants are discussed in the light of interferences between biosynthetic pathways linked to plant responses to shoot or root herbivory.

Show MeSH
Related in: MedlinePlus