Two novel disaccharides, rutinose and methylrutinose, are involved in carbon metabolism in Datisca glomerata

Abstract

Datisca glomerata forms nitrogen-fixing root nodules in symbiosis with soil actinomycetes from the genus Frankia. Analysis of sugars in roots, nodules and leaves of D. glomerata revealed the presence of two novel compounds that were identified as α-l-rhamnopyranoside-(1 → 6)-d-glucose (rutinose) and α-l-rhamnopyranoside-(1 → 6)-1-O-β-d-methylglucose (methylrutinose). Rutinose has been found previously as a/the glycoside part of several flavonoid glycosides, e.g. rutin, also of datiscin, the main flavonoid of Datisca cannabina, but had not been reported as free sugar. Time course analyses suggest that both rutinose and methylrutinose might play a role in transient carbon storage in sink organs and, to a lesser extent, in source leaves. Their concentrations show that they can accumulate in the vacuole. Rutinose, but not methylrutinose, was accepted as a substrate by the tonoplast disaccharide transporter SUT4 from Arabidopsis. In vivo 14C-labeling and the study of uptake of exogenous sucrose and rutinose from the leaf apoplast showed that neither rutinose nor methylrutinose appreciably participate in phloem translocation of carbon from source to sink organs, despite rutinose being found in the apoplast at significant levels. A model for sugar metabolism in D. glomerata is presented.

Versatile Redox Chemistry Complicates Antioxidant Capacity Assessment: Flavonoids as Milieu-Dependent Anti- and Pro-Oxidants

“…Attack on oligosaccharides, such as fructans, and phenols may lead to the formation of phenol and sugar radicals that either form sugar–phenol compounds, repolymerized oligosaccharides or polymerized phenols [41]. Rutin might also arise in such a scenario—rutinose is not known to occur as free sugar in nature [42] and fungal enzymes have been suggested to be involved in its biosynthesis [43]. Only the 16 h variant of the deoxyribose degradations assay reveals that rutin, in comparison to quercetin, might be a more efficient antioxidant when it is present during the entire Haber–Weiss reaction.…”

Plasmodesmata distribution and sugar partitioning in nitrogen-fixing root nodules of Datisca glomerata

“…Attempts to amplify a plasma membrane sucrose transporter had proved unsuccessful; reverse transcription-PCR (RT-PCR) with degenerate primers that had yielded diverse sucrose transporters from other plant species (Knop et al 2001) had only led to the amplification of a putative vacuolar class III sucrose transporter (Schubert et al 2010). …”

Distinctive Patterns of Flavonoid Biosynthesis in Roots and Nodules of Datisca glomerata and Medicago spp. Revealed by Metabolomic and Gene Expression Profiles

“…Rutinose is a common glycosylation of flavonoids in many plants ( Cuyckens et al, 2001 ), and was previously shown to occur in leaves of Datisca cannabina ( Bohm, 1988 ). Rutinose was reported to occur as an exceptionally abundant free sugar in roots, nodules, and leaves of D. glomerata and D. cannabina ( Schubert et al, 2010 ) that could not be hydrolyzed in cell extracts. Thus it is hypothesized that rutinose is synthesized as a flavonoid glycosylation and then released as a free sugar ( Schubert et al, 2010 ).…”