Project description:Brown rot fungi evolved the unique strategy to efficiently decay wood structures and selectively extract carbohydrates, and this involved the sophistical regulation of functional genes (Zhang et al., PNAS, 2016, 113: 10968-). However, the regulatory mechanisms of brown rot genes were not well known, impeding the implication and application of brown rot machinery in biomass conversions. In this work, we systematically studied the roles of environmental carbon signals (e.g., aspen, cellobiose, glucose and no-carbon) in regulating gene expression in model brown rot fungus Postia placenta by RNA-seq. We found the complex substrate aspen (Populus sp.), but not the commonly recognized disaccharide cellobiose, was the universal inducer for Carbohydrate Active Enzymes (CAZYs) expression. Even though, cellobiose clearly induced the expression of cellulase (GH5 and GH12, endoglucanase) and xylanase (GH10, endoxylanase) (cellobiose vs. no-carbon, fold change > 4), as we reported previously (Zhang and Schilling, FGB, 2017, 106: 1-). When response to easy to use carbons, P. placenta lost the CCR effect on the main-chain cleaving CAZYs expression, but kept this repressing effect on side-chain cleaving CAZYs and AAs, which indicated a clear adaption relative to that in saprotrophic ascomycete ancestors. This “loss of CCR effect” was independent of the glucose concentrations. To explore the distinctive brown rot regulatory machinery, the gene modules subjected to inducing or CCR effects were then used to predict the regulatory motifs and transcriptional factors to build the regulatory network in P. placenta. Together, these findings will facilitate us to understand the adaptions of regulatory elements in brown rot fungi, as well as the efficient brown rot strategy.
Project description:The brown rot wood decay fungus, Fomitopsis pinicola strain FP-58527, was cultivated for five dayes in media containing ground Populus tremuloides, Pinus taeda or Picea glauca wood as sole carbon source. Extracellular proteomic component was extracted and analyzed by LC-MS/MS.
Project description:The brown rot fungus, Fomitopsis pinicola strain FP-58527, was cultivated in media containing ground Populus tremuloides, Pinus taeda or Picea glauca wood as sole carbon source. Mass spectrometry analyses identified proteins likely involved in the degradation of lignocellulose. Patterns of enzymes detected varied with substrate.
Project description:The brown rot fungus, Fomitopsis pinicola strain FP-58527, was cultivated in media containing ground Populus tremuloides, Pinus taeda or Picea glauca wood as sole carbon source. Mass spectrometry analyses identified proteins likely involved in the degradation of lignocellulose. Patterns of enzymes detected varied with substrate.
Project description:Wood-degrading fungi vary in their strategies for deconstructing wood, and their competitive successes shape the rate and fate of carbon released from wood, Earth’s largest pool of aboveground terrestrial carbon. In this study, one-on-one interspecific interactions between two model brown rot (carbohydrate-selective) fungi, Gloeophyllum trabeum and Rhodonia (Postia) placenta, were studied on wood wafers where a clearly resolved interaction zone (IZ) could be generated, reproducibly. Comparative RNAseq and proteomics between the IZ and non-interacting hyphae of each species identified combative strategies for each fungus. Glycoside hydrolases were a relatively smaller portion of the interaction secretome compared to non-interacting hyphae. The interaction zone showed higher pectinase specific activity than all other sampling locations, and higher laminarinase specific activity (branched β‐glucan proxy) was seen in the IZ secretome relative to equivalent hyphae in single‐species cultures. Our efforts also identified two distinct competitive strategies in these two fungi with a shared nutritional mode (brown rot) but polyphyletic ancestral lineages. Gloeophyllum trabeum (Gloeophyllum clade) employed secondary metabolite (SM) synthesis in response to a competitor, as shown by the upregulation of several SM-synthesizing genes in the interaction. R. placenta (Antrodia clade) instead upregulated a larger variety of uncharacterized oxidoreductases in interacting hyphae, suggesting that an oxidative burst may be a response to competitors in this fungus. Both species produced several hypothetical proteins exclusively in the interaction zone, leaving abundant unknowns on the battlefield. This work supports the existence of multiple interaction strategies among brown rot fungi and highlights the functional diversity among wood decay fungi.
Project description:Wood-degrading fungi play a critical role in global carbon cycling, and their varied mechanisms for deconstruction offer pathways for industrial bioconversion. In this study, we used comparative genomics to isolate upregulation patterns among fungi with brown rot (carbohydrate-selective) or white rot (lignin-degrading) nutritional modes. Specifically, we used whole-transcriptome profiling to compare early, middle, and late decay stages on wood wafers, matching differentially-expressed gene (DEG) patterns with fungal growth and enzyme activities. This approach highlighted 34 genes uniquely upregulated in early brown rot stages, with notable candidates involved in generating reactive oxygen species (ROS) as a pretreatment mechanism during brown rot. This approach further isolated 18 genes in late brown rot stages that may be adapted to handle oxidatively-reacted lignocellulose components. By summing gene expression levels in functional classes, we also identified a broad and reliable distinction in glycoside hydrolase (GH) versus lignocellulose oxidative (LOX) transcript counts that may reflect the energy investment burden of lignin-degrading machinery among white rot fungi.