*3.8. Confirmation of AKR Gene Expression Level in the Onion Lines through qPCR Analysis*

The SNP-3 HRM marker was selected from the AKR transcript and showed higher expression levels in the resistant line group in the in silico data. qPCR was performed to confirm the gene expression levels of AKR. Before performing qPCR, RT-PCR was performed to confirm the amplification using the primer set designed for qPCR. RT-PCR showed that all seven onion lines were amplified into one band of 171 bp. qPCR was performed in six replicates by the SNP-3 primer, and the results were calculated using the ΔΔCt method. The gene expression level was normalized to the actin gene expression level and compared with the susceptible line S&P 7483 with the highest susceptibility (Figure 8). In the qPCR analysis, the expression level of the AKR gene was higher in the resistant group than in the susceptible group, with S&P 7522 showing the highest expression level and S&P 7130 showing the lowest expression level.

**Figure 8.** The gene expression level of the aldo-keto reductase (ARK) gene in the seven onion lines using the SNP-3 primer by the qPCR analysis. Four resistant lines (S&P 7522, S&P 7521, S&P 7129, and S&P 7168) and three susceptible lines (S&P 7483, S&P 7130, and S&P 7175) were analyzed. The qPCR analysis was performed in six replicates, and the standard errors are indicated as bars. Means with the same letter on the bar were not significantly different according to Duncan's multiple comparison test.
