Comparative Transcriptome Analysis Reveals the Regulation of Growth Activity in Poria cocos Under Different Light...

Background: Light is an important environmental signal that regulates the growth and metabolism of fungi. This study aims to reveal the molecular regulatory mechanism of different light durations on the growth activity of Poria cocos. Methods: By setting up three groups of light treatment: 0 days (sample 1), 15 days (sample 2), and 30 days (sample 3), and combining transcriptome sequencing (RNA-seq) with qRT-PCR for verification, the effects of light on the gene expression of Poria cocos (Poria cocos (Schw.) Wolf) were systematically analyzed. Results: A total of 4332 differentially expressed genes (DEGs) were identified in this study. Among them, the blue light-responsive genes, BLI-3 and BLI-4, were significantly upregulated at the DT15 stage, reaching 576.08 times and 31.30 times, respectively, while they were sharply downregulated at the DT30 stage. The KEGG enrichment analysis revealed that the DEGs were mainly involved in secondary metabolite synthesis, carbon metabolism, amino acid synthesis, redox reactions, and the MAPK signaling pathway. At the DT15 stage, genes related to growth metabolism, such as CYP, SNF1, and COX, were highly expressed, indicating active metabolism at this stage. However, in the DT0 and DT30 stages, ROS-related genes such as NADPH-dependent oxidoreductases were upregulated, leading to oxidative stress damage and inhibiting growth. Additionally, the high expression of BLI-3 and BLI-4 significantly activated ergosterol synthesis genes, enhancing cell membrane stability. The WGCNA co-expression network analysis revealed a high degree of correlation between BLI-4 and MAPKKK and CYP genes and proposed a potential "BLI-4-MAPKKK-CYP" regulatory axis, providing insights into the molecular pathway by which light regulates the metabolism and homeostasis of Poria cocos. Conclusions: This study has for the first time systematically revealed the molecular mechanism by which light duration regulates the growth activity of Poria cocos. It has clarified the core role of the BLI gene family in light signal perception and metabolic regulation. It has also elucidated the molecular pathways by which light regulates the synthesis of ergosterol, energy metabolism, and oxidative stress response in Poria cocos. This provides innovative theoretical support for optimizing the light regulation strategies in Poria cocos cultivation and also offers important references for the study of environmental response mechanisms in other medicinal fungi.