Activity And Specificity Of Plant Cell Wall Degrading Enzymes From Wheat And Apple Pathogens

Biomass is the only known,large-scale,renewable resource that can be converted into liquid biofuels and bio-based products to replace petroleum-derived liquid fuels and chemicals.Degradation of lignocellulosic biomass,mainly plant cell walls,by plant cell wall-degrading enzymes is a critical step for the production of biofuels or bio-based products.This process is greatly hindered by the natural complexity of plant cell walls as well as limited accessibility of surface polysaccharides,such as cellulose,by plant cell wall-degrading enzymes,such as cellulases.It is critical to gain a more profound understanding of the relationship between plant cell wall and plant cell wall-degrading enzymes produced by microbes.Recent studies suggest that plant pathogens may produce specific cocktails of plant cell wall-degrading enzymes towards their host plant’s cell walls.To confirm this idea,we profiled the activities and specificities of plant cell wall-degrading enzymes from eight different species of plant pathogenic fungi towards biomass substrates of different host species,ranging from herbaceous monocots(wheat stalk,switchgrass)and dicots(oilseed rape)and tree species(apple branch).Results of this study suggest that(1)Plant cell wall-degrading enzymes produced by wheat and apple pathogens showed relatively high activities towards their host plant’s cell wall;(2)Hemicellulase pretreatment significantly enhanced the activity of plant cell wall-degrading enzymes of wheat pathogens towards their host biomass;(3)Partial removal of lignin by peracetic acid(PAA)pretreatment removed the observed preferences of wheat and apple pathogens towards their host biomass.This study supports the idea that plant pathogens have evolved specific cocktails of plant cell wall-degrading enzymes towards their host plant’s cell wall and the observed specificity may have relevance with how cell wall components such as lignin,hemicellulose,and cellulose interact with each other.