Structural Characterization of Lignocresols from Transgenic and Wild-Type Switchgrass

Abstract

Cafferic acid-O-methyltransferases (COMT) down-regulated transgenic and wild-type switchgrass were separated into lignocresols (LCs) and sugars by a phase separation method involving 72% sulfuric acid and cresol. The isolated LCs were characterized by FTIR, GPC, 1 H NMR and 2D-HSQC to understand potential structural modification caused by transgenic engineering lignin or phase separation treatment. No significant changes were found in terms of molecular weights and the amount of incorporated p-cresols between transgenic and wild-type switchgrass LCs. However, the compositions, ratios of syringyl (S) units to guaiacyl (G) units, were changed significantly leading to decrease in S units and increase in G units for transgenic switchgrass LC. The benzodioxane structures and 5-hydroxyguaiacyl units were observed in the 2D-HSQC implied that 5-hydroxyconiferyl alcohol was incorporated into lignin as a result of COMT-down-regulation in the transgenic process.

Heteroexpression of Osa-miR319b improved switchgrass biomass yield and feedstock quality by repression of PvPCF5

“…In this study, we found miR319-PvPCF5 module increased S/G ratio and β-O-4 linkage of switchgrass. A small amount of β-β linkages was also be found in side-chain regions of switchgrass lignin [46]. However, we did not detect any β-β bond in tested DELs, which may be due to different lignin extraction and detection methods [35,46].…”

“…A small amount of β-β linkages was also be found in side-chain regions of switchgrass lignin [46]. However, we did not detect any β-β bond in tested DELs, which may be due to different lignin extraction and detection methods [35,46]. NAC-MYB-based transcriptional regulatory system regulates secondary cell wall biosynthesis and has been well studied in switchgrass [11,13,47,48].…”