(570o) Insights on Lignin Cell Wall Structure in Flooded Poplar Stems, Roots, and Adventitious Roots

Lignin, a complex biopolymer that accounts for up to 25% (by weight) of the cell wall, is one trending subject of transgenic research. Although lignin is crucial for many vital plant processes, it also significantly increases the resistance of biomass to biological conversion into biofuel. Lignin is widely considered to provide structural stability, water resistance, and microbial protection to plant stems, as it reinforces the secondary cell walls of the vascular bundles. Although lignin biosynthesis is well understood, the effects of environmental conditions on the formation and structure of lignin are not yet fully known. In this study, we aimed to distinguish between the different lignin structures and cell wall compositions of poplar plants submerged underwater up to a height of 20 cm using 2-month-old poplar plants. To compare the changes in the plant lignin formed before and after the beginning of flooding, the control and flooded plant samples were characterized using a variety of techniques, such as heteronuclear single quantum coherence (HSQC), nuclear magnetic resonance (NMR), high-performance liquid chromatography (HPLC), and UV-visible spectroscopy. The monolignol composition and interunit linkages resulting from the four different parts of the plant were investigated to understand lignin formation under flooded environmental conditions. The cell wall composition before and after flooding was studied to verify the hypothesis that the submerged part of the stem would accumulate greater quantities of lignin to provide better water resistance to the plant. Quantifying the effects of environmental changes (flooding) on lignin formation and chemistry will help us to better understand lignocellulosic biomass for the commercial processing of renewable biofuels.