Rapid Py-GC/MS assessment of the structural alterations of lignins in genetically modified plants

• Published in: Journal of analytical and applied pyrolysis 2016-09, Vol.121 (C), p.155-164
• Main Authors: Rencoret, Jorge, del Río, José Carlos, Nierop, Klaas G.J., Gutiérrez, Ana, Ralph, John
• Format: Article
• Language: English
• Subjects: Lignin; Non-woody; Pyrolysis; Transgenic plants; Whole cell-walls; Woody
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2016.07.016

•Py-GC/MS is useful for evaluation of lignin from genetically modified plants.•Py-GC/MS allows in situ analysis of transgenic plants with low lignin contents.•The pyrolysis system is critical to detect 5-OH-guaiacyl units from benzodioxanes. Genetic modifications for perturbing the lignin pathway in three different species of angiosperm plants, including non-woody (Arabidopsis and alfalfa) and woody (poplar) plants, were readily evaluated by analytical pyrolysis coupled to gas chromatography-mass spectrometry (Py-GC/MS). Pyrolysis showed that the composition of Arabidopsis plants was severely altered when the expression of the gene encoding the enzyme caffeic acid O-methyltransferase (COMT) was downregulated, resulting in a lignin largely enriched in guaiacyl (G) units (88%). Alfalfa plants in which lignin biosynthesis was modified by down-regulation of the p-coumarate 3-hydroxylase (C3H) gene, showed extremely high proportions of p-hydroxyphenyl (H) units (71%) relative to the naturally prevailing guaiacyl (G) and syringyl (S) units. Finally, Py-GC/MS analyses indicated that overexpression in poplar of the gene that encodes the enzyme ferulate 5-hydroxylase (F5H) resulted in a lignin with a higher content of syringyl lignin units (88%) compared to the wild-type control (71%). In conclusion, Py-GC/MS is a useful and convenient tool for the rapid evaluation of compositional changes in lignin from genetically modified plants.