## 3 Results and Discussion
### Validation of the Transcriptome Data by qRT-PCR  
To validate the RNAseq results, the expression levels of selected DEGs for transcription factors, lignocellulosic, and CAZymes were quantified using qRT-PCR analysis. As shown in Figure 5, the RNA-seq fold change values were basically consistent with the qRT-PCR expression patterns. Seven DEGs for upregulation and two for downregulation in the CAZymes overlapped with lignocellulosic. Therefore, the duplicated qRT-PCR results for GH1, 3, AA1, 2, and 3 in the upregulated DEGs, and GH7 and AA9 in the downregulated DEGs were removed from Figure 5. The comparison of the RNAseq and qRT-PCR data implied the accuracy of the sequencing methods (Table S5). GT15 (LE01 Gene00748), CE10 (LE01 Gene03808), AA14 (LE01 Gene07497) in CAZyme were observed to have upregulated expression, while AA7 (LE01 Gene00046) and GH79 (LE01 Gene00946) in CAZyme were downregulated in qRT-PCR. \(\beta\)-glucosidase (LE01 Gene06170, 06300, and 07491) and L-ascorbate oxidase (LE01 Gene 08723) were shown to have upregulated expression in lignocellulosic, while 1,4-\(\beta\)-cellobiosidase (LE01 Gene04829) and endo-beta-1,4-glucanase (LE01 Gene03338) were downregulated. Interestingly, the upregulated expression rates under blue light compared to the dark in pileus samples were superior to those in the stipe sample. As shown in Figure S1, the growth of pilus under blue light was more vigorous than in the dark. However, the length of the stipe was greater in the dark. The growth in stipe elongation in the dark may be more significant than under blue light. That is one indirect reason for the low expression of upregulated DEGs in the stipe. On the other hand, the upregulated DEGs for transcription factors, such as fungal-specific transcription factor (LE01 Gene05969), C2H2-zinc finger transcription factor (LE01 Gene07732, 01730, 09749, and 11531), TBP-domain-containing protein (LE01 Gene08830), and AT-hook  
Figure 5: Expression validation of selected DEGs for CAZyme, lignocellulosic, and transcription factor using qRT-PCR in mushrooms under blue light and dark (no light) conditions. Each relative expression was normalized by the mushroom _Rpl4_ housekeeping gene. transcription factor (LE01 Gene 13269), were dominantly expressed in both the pileus and the stipe. Generally, the DEG expression of CAZyme increased according to fruit body development, but the DEG expression of lignocellulosic did not. The downregulated DEGs, AA7, GH79, 1,4-\(\beta\)-cellobiosidase, and endo-beta-1,4-glucanase were significantly expressed in the stipe 2 sample under the dark. Remarkably, cell wall degradation enzyme endo-1,4-glucanase increased its expression in _Lentinula edodes_ under blue light [9], and enzyme activity increased in _Pleurotus eryngii_[43]. However, the increase in expression and activity was determined only at the primordial formation stage. In this study, endo-1,4-glucanase was observed to be highly expressed in a stipe sample in the dark during fruit body development. This may provide additional information for mushroom breeders regarding fruit body development. As for transcription factors, seven out of nine upregulated DEGs in the stipe 2 sample under blue light were detected to have the highest expression. Several studies reported upregulated expression of transcription factors in mushrooms under blue light. [PERSON] et al. [44] reported that a fungal-specific transcription factor was upregulated after blue light exposure at the mycelium stage in _Copinopsis cinerea_. C2H2 zf transcription factor was also reported to have upregulated expression under blue light in _Schizophyllum commune_[45; 46]. C2H2 zf transcription factor had the highest expression in the fruit body compared to the mycelium, aggregate, and primordia stages [45], and drastically increased the expression in dibaryon under blue light [46]. Therefore, C2H2 zf transcription factor may be most expressed in the stipe at stage 2 under blue light. C2H2 zf transcription factors are considered an abundant family.