Saccharide analysis of onion outer epidermal walls

Abstract Background Epidermal cell walls have special structural and biological roles in the life of plant. Typically they are multi-ply structures encrusted with waxes cutin which protect plant from dehydration pathogen attack. These characteristics may also reduce chemical enzymatic deconstruction wall for sugar analysis conversion to biofuels. We assessed saccharide composition outer epidermal onion scales different analytical methods. This is a particularly useful model imaging mechanics. Results were depolymerized by acidic methanolysis combined 2M trifluoracetic acid hydrolysis resultant sugars analyzed high-performance anion-exchange chromatography pulsed amperometric detection (HPAEC-PAD). Total yields based on dry weight low (53%). Removal chloroform increased 73% digestion did not improve these yields. Analysis gas chromatography/mass spectrometry (GC/MS) per- O -trimethylsilyl (TMS) derivatives methyl glycosides produced gave high yield galacturonic (GalA) but glucose (Glc) was severely reduced. In complementary fashion, GC/MS alditols permethylation substantial other neutral sugars, GalA 13 C solid-state NMR confirmed extended results revealed 15% lipid content after extraction (potentially unextractable waxes). Conclusions Although exact values vary method, our best estimate that polysaccharide comprised homogalacturonan (~ 50%), cellulose 20%), galactan 10%), xyloglucan 10%) smaller amounts polysaccharides. Low specific monosaccharides some methods be exaggerated impregnated call cautious interpretation results.