Dataset Information

Host plant shifts affect a major defense enzyme in Chrysomela lapponica.

ABSTRACT: Chrysomelid leaf beetles use chemical defenses to overcome predatory attack and microbial infestation. Larvae of Chrysomela lapponica that feed on willow sequester plant-derived salicin and other leaf alcohol glucosides, which are modified in their defensive glands to bioactive compounds. Salicin is converted into salicylaldehyde by a consecutive action of a ?-glucosidase and salicyl alcohol oxidase (SAO). The other leaf alcohol glucosides are not oxidized, but are deglucosylated and esterified with isobutyric- and 2-methylbutyric acid. Like some other closely related Chrysomela species, certain populations of C. lapponica shift host plants from willow to salicin-free birch. The only striking difference between willow feeders and birch feeders in terms of chemical defense is the lack of salicylaldehyde formation. To clarify the impact of host plant shifts on SAO activity, we identified and compared this enzyme by cloning, expression, and functional testing in a willow-feeding and birch-feeding population of C. lapponica. Although the birch feeders still demonstrated defensive gland-specific expression, their SAO mRNA levels were 1,000-fold lower, and the SAO enzyme was nonfunctional. Obviously, the loss of catalytic function of the SAO of birch-adapted larvae is fixed at the transcriptional, translational, and enzyme levels, thus avoiding costly expression of a highly abundant protein that is not required in the birch feeders.

SUBMITTER: Kirsch R

PROVIDER: S-EPMC3064323 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature

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Host plant shifts affect a major defense enzyme in Chrysomela lapponica.

Kirsch Roy R Vogel Heiko H Muck Alexander A Reichwald Kathrin K Pasteels Jacques M JM Boland Wilhelm W

Proceedings of the National Academy of Sciences of the United States of America 20110307 12

Chrysomelid leaf beetles use chemical defenses to overcome predatory attack and microbial infestation. Larvae of Chrysomela lapponica that feed on willow sequester plant-derived salicin and other leaf alcohol glucosides, which are modified in their defensive glands to bioactive compounds. Salicin is converted into salicylaldehyde by a consecutive action of a β-glucosidase and salicyl alcohol oxidase (SAO). The other leaf alcohol glucosides are not oxidized, but are deglucosylated and esterified ...[more]

PMID: 21383196

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Project description:Tomato plants are attacked by diverse herbivorous arthropods, including by cell-content-feeding mites, such as the extreme generalist Tetranychus urticae and specialists like Tetranychus evansi and Aculops lycopersici. Mite feeding induces plant defense responses that reduce mite performance. However, T. evansi and A. lycopersici suppress plant defenses via poorly understood mechanisms and, consequently, maintain a high performance on tomato. On a shared host, T. urticae can be facilitated by either of the specialist mites, likely due to the suppression of plant defenses. To better understand defense suppression and indirect plant-mediated interactions between herbivorous mites, we used gene-expression microarrays to analyze the transcriptomic changes in tomato after attack by either a single mite species (T. urticae, T. evansi, A. lycopersici) or two species simultaneously (T. urticae plus T. evansi or T. urticae plus A. lycopersici). Additionally, we assessed mite-induced changes in defense-associated phytohormones using LC-MS/MS. Compared to non-infested controls, jasmonates (JAs) and salicylate (SA) accumulated to higher amounts upon all mite-infestation treatments, but the response was attenuated after single infestations with defense-suppressors. Strikingly, whereas 8 to 10% of tomato genes were differentially expressed upon single infestations with T. urticae or A. lycopersici, respectively, only 0.1% was altered in T. evansi-infested plants. Transcriptome analysis of dual-infested leaves revealed that A. lycopersici primarily suppressed T. urticae-induced JA defenses, while T. evansi dampened T. urticae-triggered host responses on a transcriptome-wide scale. The latter suggests that T. evansi not solely down-regulates plant gene expression, but rather directs it back towards housekeeping levels. Our results provide valuable new insights into the mechanisms underlying host defense suppression and the plant-mediated facilitation of competing herbivores.

Dataset Information

Host plant shifts affect a major defense enzyme in Chrysomela lapponica.

Publications

Host plant shifts affect a major defense enzyme in Chrysomela lapponica.

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