Genomic and Transcriptomic Insights into Carbon-Source and Temporal Induction of a Diverse Set of Lignocellulolytic Enzymes in Irpex lacteus QJ

Abstract

The white-rot fungus Irpex lacteus is recognized for its strong ligninolytic and polysaccharide-degrading capacity, but the key advantages in degrading lignocellulose and the regulation of its enzyme systems remain poorly understood. In this study, we identified a rich repertoire of carbohydrate-active enzymes in the genome of I. lacteus QJ. Relative to other white-rot fungi, an expanded glycoside hydrolase gene family in I. lacteus QJ suggesting strong potential for lignocellulose degradation. When I. lacteus QJ was cultivated on glucose or wheat straw for 4 and 8 days, wheat straw strongly induced carbohydrate-active enzyme genes on day 4, while ligninolytic enzyme genes exhibited delayed upregulation on day 8. The cellobiose dehydrogenase plays an important role in the degradation processes. Its expression pattern is consistent with that of cellulase, and it can support peroxidase activity by providing H2O2. These findings reveal temporal coordination between polysaccharide- and lignin-degrading enzymes, providing new theoretical ideas for the application of I. lacteus during the degradation process. Our results not only improve the mechanistic understanding of fungal lignocellulose deconstruction but also inform strategies to enhance biological pretreatment of agricultural residues for biorefinery applications.