Quantifying Chemically Modified Acetylation Induced Changes in the Plant Secondary Cell Wall Structure and Dynamics

Wood that is resistant to fungal degradation is highly desirable, and chemical acetylation is one way to inhibit wood decay. The open question is whether acetylation inhibits decay strictly by reducing moisture content within the cell wall or if specific interactions with the acetyl group hinder motion within the cell wall and further inhibit decay. We investigate these hypotheses through molecular simulation, acetylating exposed hemicellulose and lignin hydroxyl groups in a secondary plant cell wall model. By comparing diffusion within the model, we find that acetyl group interactions alone do not account for reduced transport, with only modest changes in diffusion when water saturated acetylated cell walls expand at a constant water content. The most substantial changes in diffusion occur where the additional acetylation displaces water, decreasing the moisture content for the cell wall. These findings elucidate the molecular mechanism through which acetylation affects secondary plant cell walls at atomic resolution.