## 3 Results
### COG and KEGG Enrichment Analysis of DEPs  
From the COG database annotation results (Figure 3A), we observed that during the developmental transition from GP to GPP, the highest number of differential proteins are enriched in post-translational modifications and protein translocation, followed by general functions and energy production transitions. Functions related to RNA processing modification, chromatin structure, prophage, transposons, and nuclear structure did not show significant enrichment. A similar trend is evident in the transition from GP to GSP, where we observed the highest number of differential proteins. It is hypothesized that this function plays a pivotal role in sclerotium formation through mycelium coalescence, nutrient accumulation, and functional proteins. The biosynthesis function was found to \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Diff Set** & **Total Number** & **Up- Regulated** & **Down- Regulated** & **Up- Regulated Proportion (\%)** & **Down-Regulated Proportion (\%)** \\ \hline GPP\_vs\_GSP & 44 & 24 & 20 & 54.55 & 45.45 \\ GP\_vs\_GPP & 520 & 372 & 148 & 71.54 & 28.46 \\ GP\_vs\_GSP & 500 & 348 & 152 & 69.60 & 30.40 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Statistics of differential protein quantity. be weakened between the transition from the GPP to the GSP stage, indicating a cessation of biological processes related to fungal morphology construction and ectomycorrhizal formation. Instead, a considerable amount of nutrient conversion into energy was needed to support growth. Proteins involved in specific functions were not enriched during this stage. In addition to protein translocation, differentially expressed proteins increased in secondary metabolite biosynthesis, transport, and catabolism; energy production conversion; and amino acid and carbohydrate transport metabolism. During the reproductive growth of the fruiting body, intensified mitosis and a surge in expressed products were involved in cell division, promoting the construction of sporophores and further development. Protein translocation and post-translational modifications occur throughout all stages of _T. gambajun's_ lifecycle, from basic vegetative growth to reproductive growth. These processes involve a multitude of small-molecule secreted proteins, signaling proteins, and other proteins with unknown functions, facilitating the essential conditions for morphological construction, cell division, differentiation, signal transduction, and the induction of ectomycorrhizae production by plant hosts. In the reproductive growth stage, the focus shifts to the amino acid and carbohydrate metabolic processes. Etomycorrhizal fungi, which are unable to acquire nutrients through frequent catabolism like saprophytic fungi, generate their own energy to fuel energy-consuming pathways, such as aerobic respiration, fatty acid metabolism, and the TCA cycle. This is crucial to complete the transformation from the primordium to the fruiting body in a relatively short period, which is achieved through cell division promotion and cell cycle regulation. Figure 2: _Cont._  
Figure 3: \(Cont\). Figure 2: Results of proteomic examination: (**A**) volcano plots of three comparison stages; (**B**) heatmap of all proteins; (**C**) PCA distribution among samples, where the X-axis represents the first principal component, and the Y-axis represents the second principal component; (**D**) Venn diagram of DEPs. Figure 3: _Cont_. In the KEGG enrichment results (Figure 3B, Table S4), the most distinct pathway for differential proteins was found to be antibiotic biosynthesis between the mycelium and primordium stages (GP vs. GPP). Annotated DEPs included transaldolase, chorismate synthase, ornithine carbamosyltransferase, arginase, and methylsterol monooxygenase, suggesting a connection to the mycelium's early competition with other fungi and bacteria for an ecological niche in the host plant, as well as defense against pathogen invasion.