Cell Wall Strengthening and Remodeling Provide New Insights on Sclerotia Development of Medicinal Fungus Polyporus Umbellatus

Sclerotium is a special form of many species of fungi and cell wall thickening is a common phenomenon in sclerotium. Rational manipulation of sclerotium would be an innovative approach for pathogenic control as well as for medicinal fungal resource revival. Sclerotia of Polyporus umbellatus were used to treat multiple human diseases. However, the mechanism of thickened cell wall (TCW) is still unclear. In this study, Sequential Windowed Acquisition of all THeoretical fragment ions spectra-MS (SWATH-MS) and parallel reaction monitoring (PRM) technology were introduced to demonstrate biomarkers at protein level associated with TCW as sclerotia development from initial sclerotia (IS) to developmental and mature sclerotia (DS and MS). 72 differentially expressed proteins (DEPs) were associated with TCW, and evidence supported presence and accumulation of chitin, glycan, xylcan and hydrophobins in the cell wall of P. umbellatus sclerotia. Puctg112, a new hydrophobin in P. umbellatus expressed up sharply with DS/IS 119.85 and MS/IS 128.17, and located at cell wall and septum of hypha in sclerotia by immune colloidal gold technique. In addition, sclerotial cell wall could be remodeled via O-mannosylation, O-fucosylation and deacetylation to strengthen cell wall. This study provides new insights on fungal cell wall especially to sclerotia-formed fungus.