title: Glucan-rich diet is digested and taken up by the carnivorous sundew (Drosera rotundifolia L.): implication for a novel role of plant β-1,3-glucanases.
abstract: Carnivory in plants evolved as an adaptation strategy to nutrient-poor environments. Thanks to specialized traps, carnivorous plants can gain nutrients from various heterotrophic sources such as small insects. Digestion in traps requires a coordinated action of several hydrolytic enzymes that break down complex substances into simple absorbable nutrients. Among these, several pathogenesis-related proteins including β-1,3-glucanases have previously been identified in digestive fluid of some carnivorous species. Here we show that a single acidic endo-β-1,3-glucanase of ~50 kDa is present in the digestive fluid of the flypaper-trapped sundew (Drosera rotundifolia L.). The enzyme is inducible with a complex plant β-glucan laminarin from which it releases simple saccharides when supplied to leaves as a substrate. Moreover, thin-layer chromatography of digestive exudates showed that the simplest degradation products (especially glucose) are taken up by the leaves. These results for the first time point on involvement of β-1,3-glucanases in digestion of carnivorous plants and demonstrate the uptake of saccharide-based compounds by traps. Such a strategy could enable the plant to utilize other types of nutritional sources e.g., pollen grains, fungal spores or detritus from environment. Possible multiple roles of β-1,3-glucanases in the digestive fluid of carnivorous sundew are also discussed.
authors.affiliation: Institute of Plant Genetics and Biotechnology, Slovak Academy of Sciences, Akademická 2, P.O. Box 39A, 950 07, Nitra, Slovak Republic, jaroslav.michalko@savba.sk.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Michalko
authors.forename: Peter
authors.initials: P
authors.lastname: Socha
authors.forename: Patrik
authors.initials: P
authors.lastname: Mészáros
authors.forename: Alžbeta
authors.initials: A
authors.lastname: Blehová
authors.forename: Jana
authors.initials: J
authors.lastname: Libantová
authors.forename: Jana
authors.initials: J
authors.lastname: Moravčíková
authors.forename: Ildikó
authors.initials: I
authors.lastname: Matušíková
mesh_terms: D000818:Animals; D060435:Carnivory; D029787:Drosera / Q000201:enzymology*; D043326:Glucan 1,3-beta-Glucosidase / Q000378:metabolism*; D005936:Glucans; D006868:Hydrolysis; D018515:Plant Leaves / Q000201:enzymology; D011134:Polysaccharides / Q000378:metabolism*; D059748:Proteolysis; D047071:beta-Glucans / Q000378:metabolism*
chemical_list: D005936:Glucans; D011134:Polysaccharides; D047071:beta-Glucans; C008247:laminaran; D043326:Glucan 1,3-beta-Glucosidase