*3.1. RAPD and Phylogenetic Analysis*

Four (S&P 7522, S&P 7521, S&P 7129, and S&P 7168) gray mold-resistant and three (S&P 7130, S&P 7175, and S&P 7483) susceptible onion lines were amplified using 40 OPERON random primers, and the polymorphic bands were confirmed by electrophoresis. Most of the amplified band sizes ranged from 200 bp to 2500 bp, and 124 bands (38%) of the 330 bands showed polymorphisms. The RAPD analysis was repeated at least three times to obtain reproducibility, and the presence or absence of amplified bands was transformed into binary data. The binary data were converted into dendrograms by using the UP-GMA methods of the XLSTAT program using Jaccard coefficients (Figure 1). The genetic similarity within the group was 78.27%, and the genetic similarity between the groups was 21.73%. Based on the phylogenetic analysis, a genetic relationship between the seven lines was confirmed. The results of the phylogenetic analysis were compared with the pedigrees of the seven breeding lines to confirm the reliability of the RAPD (Figure S1). The phylogenic analysis results were consistent with the genetic relationship of the pedigree of the breeding lines.
