## 3 Results
### Transcriptional Regulation of Phenylpropanol Pathway and Tannin Metabolism Regulation Genes  
Further analysis was conducted, focusing on the genes (Table 5) of interest in the phenylpropanol biochemical pathway as summarized in Figure 8, in order to explore the relationship between their expression patterns. The expression levels of the selected genes belonging to the phenylpropanol pathway were further studied. F3H expression was upregulated in S1-S2 and S1-S3 but downregulated in S2-S3. Statistically, it was significant only in the P0 treatment. F3'H expression showed a downregulation in all P treatments except for the S2-S3 comparison in P1 and P2 treatments where it was not statistically significant. A similar pattern was observed for F3'5'H expression levels. DHM expression was downregulated and statistically significant only in S1-S3 and S2-S3 of the P0 treatment. DFR expression was downregulated in all conditions except for the S2-S3 comparison in P0 and P1 treatments where it was not statistically significant. bHLH expression was downregulated in all comparisons except for the S2-S3 comparison in P1 and P2 treatments where significance was not observed. FLS expression was upregulated in all comparisons except for the S1-S2 in both P1 and P2 treatments where it was not statistically significant. Notably, LAR and ANR expressions were significantly downregulated in all P treatments when comparing S1-S3. As indicated in the volcano plots (Figure 9), the majority of the genes of the phenylpropanol pathway are downregulated. The comparison S1-S3 reveals genes with the most pronounced downregulated expression, followed by the S1-S2 comparison and then the S2-S3 comparison, in descending order of downregulation intensity (Table S3). The top five downregulated genes \begin{table}
\begin{tabular}{c c} \hline
**Leu ID** & **Gene of Interest** \\ \hline Leu.2 BRY.3g053120 & flavanone-3-hydroxylase (F3H) \\ Leu.2 BRY.7g062870 & flavenoid 3′-hydroxylase (F3’H) \\ Leu.2 BRY.4g060220 & flavonol synthase (FLS) \\ Leu.2 BRY.3g016660 & flavonoid 3′,5′-hydroxylase (F3′5′H) \\ Leu.2 BRY.5g073610 & bifunctional dihydroflavonol 4-reductase (DFR) \\ Leu.2 BRY.2g040110 & dihydrotrien reductase (DHM) \\ Leu.2 BRY.1g048740 & leucontheocyanidin reductase (LAR) \\ Leu.2 BRY.4g058260 & anthocyanin reductase (ANR) \\ Leu.2 BRY.1g063710 & basic helix-loop-helix (bHLH) \\ \hline \end{tabular}
\end{table} 
Table 5: The table represents the genes that are expressed in key positions in the phenylpropanol pathway, and they were studied further for their role in the pathway and their impact on tannin biosynthesis. The Leu ID represents the identification code for each gene retrieved from Phytozone v.13 from the _Lens culinaris_ reference genome (Leu.2 BRY v.2.0). in the phenylpropanol pathway are F3\({}^{\prime}\)H, bHLH, F3\({}^{\prime}\)5\({}^{\prime}\)H and DFR, all of which belong in the P0 treatment and S1-S3 comparison, and F3\({}^{\prime}\)H that belongs in the P1 treatment and S1-S3 comparison (Figure 9). Hierarchical clustering, employing Pearson correlation, was applied to normalized count data in order to create a heatmap visualizing the expression patterns of selected phenylpropanol pathway genes across the samples. In S1, all the studied genes were highly expressed, except for F3H, FLS and DHM. FLS displayed the lowest expression, followed by F3H. Meanwhile, DHM's expression, at least in this seed maturity stage, seemed to be influenced by the P treatment, with a decrease observed in the P1 and P2 treatments compared to P0. In S2, the expression of all genes was generally low across all three P treatments, except for F3H, which exhibited higher expression levels in all three P treatments, with the most notable expression observed in P0. In S3, a low expression pattern was evident in both P0 and P1 for most genes, with the exception of the FLS gene, which displayed a significantly increased expression. In P2, the expression of FLS decreased to moderate levels, while an increase in F3H expression was observed.