Lignocellulose, the main component of wood and agro-residues, represents the most abundant biomass available on Earth [1,2]. However, the recalcitrant structure formed by its primary constituents, cellulose, hemicellulose, and lignin, prevents the effective utilization of lignocellulose. White-rot fungi are recognized as the most efficient natural decomposers of lignocellulose [3]. Currently, agro-residues including bran, cottonseed hulls, sawdust, bagasse, corn cobs, and rice straw, serve as indispensable nutrient sources for mushroom cultivation [[4], [5], [6]]. For instance, Flammulina velutipes can be effectively cultivated using substrates such as cottonseed hulls, corncobs, sawdust, and bagasse [7], while rice straw is a primary substrate for Volvariella volvacea production [8]. When Pleurotus ostreatus was cultivated on substrates including straw, rice, peanut leaves, and bagasse, significant differences in nutrient content were observed [9]. In the case of P. floridar, its growth and yield exhibited a significant upward trend with the increasing content of corn husks in a medium mixed with corn husks and wood sawdust. Notably, superior yield and other biological indicators of P. floridar were obtained when cultivated in a medium composed of 100 % of corn husks [10]. Moreover, Ganoderma lucidum cultivated on bagasse exhibited more rapid mycelium growth and higher biological efficiency compared to cottonseed hulls [11]. These observations indicate that white-rot fungi display distinct substrate-specific preferences, which depend on the compositional differences in lignin, cellulose, and hemicellulose within various substrates. Different white-rot fungi also adopt diverse degradation patterns for lignocellulose. For example, P. ostreatus, Coriolus versicolor, and Ceriporiopsis subvermispora, prioritize lignin degradation over cellulose, whereas Phanerochaete chrysosporium degrades all components simultaneously [12]. Consequently, research on the degradation of different agro-residues by white-rot fungi will facilitate the more effective utilization and biotransformation of lignocellulose.

Oudemansiella raphanipes is a widely cultivated mushroom in China with the commercial name Changgengu or Heipijizong [13]. It has gained increasing research attention in recent years due to its special flavor, high nutritional content, and pharmacological properties [[13], [14], [15]]. As a white-rot fungus, O. raphanipes possesses strong lignocellulose degrading capabilities [16,17]. Since its artificial domesticated in 1986, cultivation practices have primarily adapted methods used for Lentinula edodes and wood ear, relying on substrates like sawdust, cottonseed hulls, and corn cob powder with soil covering in the field for optimal yield [13]. However, there is a lack of in-depth understanding of the cultivation substrates and the relative lignocellulose degradation mechanism of O. raphanipes.

Fungal nutrient acquisition from lignocellulosic biomass relies on the secretion of specialized enzymes tailored to available carbon sources [18]. The lignocellulose degradation process involves complex extracellular hydrolytic systems dominated by carbohydrate-active enzymes (CAZymes) and lignin-modification enzymes (LMEs) [[19], [20], [21]]. Substrate type and complexity significantly influence the secretome profiles, thereby impacting fungal growth and development [22,23]. The diverse strategies for lignocellulose degradation could be reflected in the differences among the secretomes, making comparative secretomic analysis a powerful tool to detect the enzyme composition, degradation step coordination (interactions and synergies), and novel enzyme discovery [[24], [25], [26]]. Recently, secretomic studies on white-rot fungi such as L. edodes, Morchella importuna, P. ostreatus, P. eryngii, Agaricus bisporus, etc, have been widely conducted [23,[27], [28], [29], [30]]. However, these investigations primarily focused on 1–3 common agro-residues (e.g. sawdust, bagasse, rice straw) and lacked comprehensive comparisons across diverse substrates. Current research on O. raphanipes is limited to individual cellulose- or lignin-degrading enzymes involved in lignocellulose degradation, with no systematic analysis of its enzyme induction profiles or degradation patterns under different substrates. Therefore, exploring the effects of a broader range of agro-residues on secreted enzyme profiles of O. raphanipes is critical.

Our previous complete genome sequencing of O. raphanipes revealed its rich repertoire of lignocellulolytic enzymes [17]. Integrating secretomic analysis with genomic information can provide critical insight into the extracellular enzyme systems involved in substrate degradation. The mycelial growth phase was selected due to its crucial role in lignocellulose breakdown [31]. Here, we evaluated O. raphanipes mycelia growth and extracellular enzyme activities of laccase, manganese peroxidase, cellulase, xylanase, and amylase in culture supernatants across eight agro-residues-based media, followed by comparative secretome profiling. This investigation represents the first comprehensive characterization of O. raphanipes extracellular enzyme profiles induced by diverse agro-residues, aiming to elucidate its lignocellulose degradation mechanisms and provide secretomic insights for optimizing cultivation substrates.