(221b) Correlation of Expression Patterns in Wood-Degrading Brown Rot Fungi to Wood Modifications: Using Space As a Gauge for Time

Brown rot fungi consolidate enzymatic bioprocessing with a non-enzymatic pretreatement that could be chemically mimicked in an engineered process. Wood degraded by brown rot fungi is characterized by a rapid depolymerization of cellulose while lignin is primarily demethylated and left in place. Brown rot fungi accomplish this by producing a diffuse, hydroxyl radical-producing Fenton system at a distance from hyphae and discrete from secreted cellulases. This co-localization of free radicals and hydrolytic enzymes is intuitively not feasible, yet it is a hallmark of the brown rot mechanism, as theorized. Previous work spatially characterizing wood wafers decayed by Postia placenta indicate that depolymerization of wood polysaccharides preceded the secretion of endoglucanases as well as lignin modifications, indicating a role for an unknown cellulolytic mechanism during early colonization. My work is focused on spatially mapping gene expression along the advancing hyphal front. Unlike previous analyses comparing expression as a function of substrate, my goal is to create a temporal series by sampling along a gradient of directional growth.  This system will be further investigated using RT-qPCR and RNA-seq to identify genes important in incipient wood decay stages. This will allow the study of the colonization of intact wood at a much finer timescale than previous expression studies in brown rot fungi, and help identify the mechanisms brown rot fungi use to extract glucose from wood without first removing lignin.