Phenolic glycosides of the Salicaceae and their role as anti-herbivore defenses

Boeckler, G. Andreas; Gershenzon, Jonathan; Unsicker, Sybille B.

doi:10.1016/j.phytochem.2011.01.038

Cited by 284 publications

(239 citation statements)

References 134 publications

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“…For instance, poplars and other Salicaceae have evolved complicated hydroxycinnamate pathways, by which they accumulate a vast array of phenolic esters, and their Glc or glycosidic derivatives, such as populoside, salicin, tremuloidin, trichocarposide, etc. (Chen et al, 2010;Boeckler et al, 2011), whereas other major group of gymnosperms and angiosperms are able to produce monolignol esters through acylation (e.g., coniferyl acetate) then reduce them to a subset of volatile phenylpropenes (Koeduka , 2006). Therefore, the 4-O-methylated compounds in different species, predicatively, can have sharply different metabolic fates, depending on the promiscuities of intrinsic enzymes or pathways being recruited.…”

Section: Expressing Momt Diversifies Phenolic Ester Repertoriesmentioning

confidence: 99%

An Engineered Monolignol 4-O-Methyltransferase Depresses Lignin Biosynthesis and Confers Novel Metabolic Capability in Arabidopsis

et al. 2012

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Although the practice of protein engineering is industrially fruitful in creating biocatalysts and therapeutic proteins, applications of analogous techniques in the field of plant metabolic engineering are still in their infancy. Lignins are aromatic natural polymers derived from the oxidative polymerization of primarily three different hydroxycinnamyl alcohols, the monolignols. Polymerization of lignin starts with the oxidation of monolignols, followed by endwise cross-coupling of (radicals of) a monolignol and the growing oligomer/polymer. The para-hydroxyl of each monolignol is crucial for radical generation and subsequent coupling. Here, we describe the structure-function analysis and catalytic improvement of an artificial monolignol 4-O-methyltransferase created by iterative saturation mutagenesis and its use in modulating lignin and phenylpropanoid biosynthesis. We show that expressing the created enzyme in planta, thus etherifying the para-hydroxyls of lignin monomeric precursors, denies the derived monolignols any participation in the subsequent coupling process, substantially reducing lignification and, ultimately, lignin content. Concomitantly, the transgenic plants accumulated de novo synthesized 4-O-methylated soluble phenolics and wall-bound esters. The lower lignin levels of transgenic plants resulted in higher saccharification yields. Our study, through a structure-based protein engineering approach, offers a novel strategy for modulating phenylpropanoid/lignin biosynthesis to improve cell wall digestibility and diversify the repertories of biologically active compounds.

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Section: Expressing Momt Diversifies Phenolic Ester Repertoriesmentioning

confidence: 99%

An Engineered Monolignol 4-O-Methyltransferase Depresses Lignin Biosynthesis and Confers Novel Metabolic Capability in Arabidopsis

et al. 2012

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“…Poplars synthesize and accumulate several classes of phenolic metabolites, including salicinoids (phenolic glycosides), anthocyanins, PAs, and low molecular weight phenolic acids and their esters, in leaves, stems, and roots (Pearl and Darling, 1971;Palo, 1984;Tsai et al, 2006;Boeckler et al, 2011). Salicinoids and PAs are generally the most abundant secondary metabolites and together can make up to 30% to 35% of leaf dry weight (Lindroth and Hwang, 1996;Tsai et al, 2006).…”

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confidence: 99%

Flavan-3-ols Are an Effective Chemical Defense against Rust Infection

et al. 2017

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Phenolic secondary metabolites are often thought to protect plants against attack by microbes, but their role in defense against pathogen infection in woody plants has not been investigated comprehensively. We studied the biosynthesis, occurrence, and antifungal activity of flavan-3-ols in black poplar (Populus nigra), which include both monomers, such as catechin, and oligomers, known as proanthocyanidins (PAs). We identified and biochemically characterized three leucoanthocyanidin reductases and two anthocyanidin reductases from P. nigra involved in catalyzing the last steps of flavan-3-ol biosynthesis, leading to the formation of catechin [2,3-trans-(+)-flavan-3-ol] and epicatechin [2,3-cis-(2)-flavan-3-ol], respectively. Poplar trees that were inoculated with the biotrophic rust fungus (Melampsora larici-populina) accumulated higher amounts of catechin and PAs than uninfected trees. The de novo-synthesized catechin and PAs in the rust-infected poplar leaves accumulated significantly at the site of fungal infection in the lower epidermis. In planta concentrations of these compounds strongly inhibited rust spore germination and reduced hyphal growth. Poplar genotypes with constitutively higher levels of catechin and PAs as well as hybrid aspen (Populus tremula 3 Populus alba) overexpressing the MYB134 transcription factor were more resistant to rust infection. Silencing PnMYB134, on the other hand, decreased flavan-3-ol biosynthesis and increased susceptibility to rust infection. Taken together, our data indicate that catechin and PAs are effective antifungal defenses in poplar against foliar rust infection.

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“…Young caterpillars primarily feed on mature leaves of B. nigra, but after the third instar, they move to fresh tissues with higher glucosinolate content, such as flowers and buds (Smallegange et al, 2007). Therefore, descriptions of plantherbivore interactions frequently emphasize specialized (secondary) metabolism (Simmonds, 2003;van Dam et al, 2004;Poelman et al, 2010;Boeckler et al, 2011;Lof et al, 2013;Onkokesung et al, 2014). However, there is an extensive functional overlap between the growth-and defense-related aspects of plant metabolism, and reconfiguration at the level of primary and energy metabolism can play a central role in the processes of stress tolerance, signal transmission, and direct defense (Both et al, 2005;Rolland et al, 2006;Schwachtje and Baldwin 2008;Fernandez et al, 2010).…”

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confidence: 99%

Central Metabolic Responses to Ozone and Herbivory Affect Photosynthesis and Stomatal Closure

et al. 2016

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Plants have evolved adaptive mechanisms that allow them to tolerate a continuous range of abiotic and biotic stressors. Tropospheric ozone (O 3 ), a global anthropogenic pollutant, directly affects living organisms and ecosystems, including plant-herbivore interactions. In this study, we investigate the stress responses of Brassica nigra (wild black mustard) exposed consecutively to O 3 and the specialist herbivore Pieris brassicae. Transcriptomics and metabolomics data were evaluated using multivariate, correlation, and network analyses for the O 3 and herbivory responses. O 3 stress symptoms resembled those of senescence and phosphate starvation, while a sequential shift from O 3 to herbivory induced characteristic plant defense responses, including a decrease in central metabolism, induction of the jasmonic acid/ethylene pathways, and emission of volatiles. Omics network and pathway analyses predicted a link between glycerol and central energy metabolism that influences the osmotic stress response and stomatal closure. Further physiological measurements confirmed that while O 3 stress inhibited photosynthesis and carbon assimilation, sequential herbivory counteracted the initial responses induced by O 3 , resulting in a phenotype similar to that observed after herbivory alone. This study clarifies the consequences of multiple stress interactions on a plant metabolic system and also illustrates how omics data can be integrated to generate new hypotheses in ecology and plant physiology.

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Phenolic glycosides of the Salicaceae and their role as anti-herbivore defenses

Cited by 284 publications

References 134 publications

An Engineered Monolignol 4-O-Methyltransferase Depresses Lignin Biosynthesis and Confers Novel Metabolic Capability in Arabidopsis

An Engineered Monolignol 4-O-Methyltransferase Depresses Lignin Biosynthesis and Confers Novel Metabolic Capability in Arabidopsis

Flavan-3-ols Are an Effective Chemical Defense against Rust Infection

Central Metabolic Responses to Ozone and Herbivory Affect Photosynthesis and Stomatal Closure

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