Dataset Information

Plant Defensive ?-Glucosidases Resist Digestion and Sustain Activity in the Gut of a Lepidopteran Herbivore.

ABSTRACT: Two-component activated chemical defenses are a major part of many plants' strategies to disrupt herbivory. The activation step is often the ?-glucosidase-catalyzed removal of a glucose moiety from a pro-toxin, leading to an unstable and toxic aglycone. While some ?-glucosidases have been well studied, several aspects of their roles in vivo, such as their precise sites of enzymatic activity during and after ingestion, and the importance of particular isoforms in plant defense are still not fully understood. Here, plant defensive ?-glucosidases from maize, white mustard and almonds were shown to resist digestion by larvae of the generalist lepidopteran Spodoptera littoralis, and the majority of the ingested activities toward both general and plant pro-toxic substrates was recovered in the frass. Among other proteins potentially involved in defense, we identified specific plant ?-glucosidases and a maize ?-glucosidase aggregating factor in frass from plant-fed insects using proteomic methods. We therefore found that, while S. littoralis larvae efficiently degraded bulk food protein during digestion, ?-glucosidases were among a small number of plant defensive proteins that resist insect digestive proteolysis. These enzymes remain intact in the gut lumen and frass and can therefore further catalyze the activation of plant defenses after ingestion, especially in pH-neutral regions of the digestive system. As most of the ingested enzymatic activity persists in the frass, and only particular ?-glucosidases were detected via proteomic analyses, our data support the involvement of specific isoforms (maize ZmGlu1 and S. alba MA1 myrosinase) in defense in vivo.

SUBMITTER: Vassao DG

PROVIDER: S-EPMC6186830 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Publications

Plant Defensive β-Glucosidases Resist Digestion and Sustain Activity in the Gut of a Lepidopteran Herbivore.

Vassão Daniel Giddings DG Wielsch Natalie N Gomes Ana Maria de Melo Moreira AMMM Gebauer-Jung Steffi S Hupfer Yvonne Y Svatoš Aleš A Gershenzon Jonathan J

Frontiers in plant science 20181008

Two-component activated chemical defenses are a major part of many plants' strategies to disrupt herbivory. The activation step is often the β-glucosidase-catalyzed removal of a glucose moiety from a pro-toxin, leading to an unstable and toxic aglycone. While some β-glucosidases have been well studied, several aspects of their roles <i>in vivo</i>, such as their precise sites of enzymatic activity during and after ingestion, and the importance of particular isoforms in plant defense are still no ...[more]

PMID: 30349548

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Project description:BACKGROUND:A molecular population genetics understanding is central to the study of ecological and evolutionary functional genomics. Population genetics identifies genetic variation and its distribution within and among populations, it reveals the demographic history of the populations studied, and can provide indirect insights into historical selection dynamics. Here we use this approach to examine the demographic and selective dynamics acting of a candidate gene involved in plant-insect interactions. Previous work documents the macroevolutionary and historical ecological importance of the nitrile-specifier protein (Nsp), which facilitated the host shift of Pieridae butterflies onto Brassicales host plants approximately 80 Myr ago. RESULTS:Here we assess the microevolutionary dynamics of the Nsp gene by studying the within and among-population variation at Nsp and reference genes in the butterfly Pieris rapae (Small Cabbage White). Nsp exhibits unexpectedly high amounts of amino acid polymorphism, unequally distributed across the gene. The vast majority of genetic variation exists within populations, with little to no genetic differentiation among four populations on two continents. A comparison of synonymous and nonsynonymous substitutions in 70 randomly chosen genes among P. rapae and its close relative Pieris brassicae (Large Cabbage White) finds Nsp to have a significantly relaxed functional constraint compared to housekeeping genes. We find strong evidence for a recent population expansion and no role for strong purifying or directional selection upon the Nsp gene. CONCLUSIONS:The microevolutionary dynamics of the Nsp gene in P. rapae are dominated by recent population expansion and variation in functional constraint across the repeated domains of the Nsp gene. While the high amounts of amino acid diversity suggest there may be significant functional differences among allelic variants segregating within populations, indirect tests of selection could not conclusively identify a signature of historical selection. The importance of using this information for planning future studies of potential performance and fitness consequences of the observed variation is discussed.

Dataset Information

Plant Defensive ?-Glucosidases Resist Digestion and Sustain Activity in the Gut of a Lepidopteran Herbivore.

Publications

Plant Defensive β-Glucosidases Resist Digestion and Sustain Activity in the Gut of a Lepidopteran Herbivore.

Similar Datasets

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