Year: 2021
Type: article
Abstract: Background Epidermal cell walls have special structural and biological roles in the life of the plant. Typically they are multi-ply structures encrusted with waxes and cutin which protect the plant from dehydration and pathogen attack. These characteristics may also reduce chemical and enzymatic deconstruction of the wall for sugar analysis and conversion to biofuels. We have assessed the saccharide composition of the outer epidermal wall of onion scales with different analytical methods. This wall is a particularly useful model for cell wall imaging and mechanics. Results Epidermal walls were depolymerized by acidic methanolysis combined with 2M trifluoracetic acid hydrolysis and the resultant sugars were analyzed by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Total sugar yields based on wall dry weight were low (53%). Removal of waxes with chloroform increased the sugar yields to 73% and enzymatic digestion did not improve these yields. Analysis by gas chromatography/mass spectrometry (GC/MS) of per- O -trimethylsilyl (TMS) derivatives of the sugar methyl glycosides produced by acidic methanolysis gave a high yield for galacturonic acid (GalA) but glucose (Glc) was severely reduced. In a complementary fashion, GC/MS analysis of methyl alditols produced by permethylation gave substantial yields for glucose and other neutral sugars, but GalA was severely reduced. Analysis of the walls by 13 C solid-state NMR confirmed and extended these results and revealed 15% lipid content after chloroform extraction (potentially cutin and unextractable waxes). Conclusions Although exact values vary with the analytical method, our best estimate is that polysaccharide in the outer epidermal wall of onion scales is comprised of homogalacturonan (~ 50%), cellulose (~ 20%), galactan (~ 10%), xyloglucan (~ 10%) and smaller amounts of other polysaccharides. Low yields of specific monosaccharides by some methods may be exaggerated in epidermal walls impregnated with waxes and cutin and call for cautious interpretation of the results.
Source: Biotechnology for Biofuels
Institutions: Pennsylvania State University, Louisiana State University
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,790
Awards: TAS::89 0227::TAS RECOVERY; RECOVERY ACT - CENTER FOR LIGNOCELLULOSE STRUCTURE AND FORMATION -- EFRC; PI - DANIEL COSGROVE, G1948681064, TAS::89 0227::TAS RECOVERY; RECOVERY ACT - CENTER FOR LIGNOCELLULOSE STRUCTURE AND FORMATION -- EFRC; PI - DANIEL COSGROVE, G3700436328, G5025091364, G604936351, THE CENTER FOR PLANT AND MICROBIAL COMPLEX CARBOHYDRATES AT THE UNIVERSITY OF GEORGIA COMPLEX CARBOHYDRATE RESEARCH CENTER, G776528767, THE CENTER FOR PLANT AND MICROBIAL COMPLEX CARBOHYDRATES AT THE UNIVERSITY OF GEORGIA COMPLEX CARBOHYDRATE RESEARCH CENTER
OpenAlex ID: W3137840994