*4.2. Identification QTL with the Resistance to P. capsici Traits*

Previous studies have showed that the major QTLs related to resistance to *P. capsici* are situated on Chr05, despite the use of various resistant lines, pepper populations, or *P. capsici* isolates [23,26,27,32,51]. Mallard et al. (2013) utilized published pepper genome information and identified three major QTLs, namely, *Pc5.1*, *Pc5.2*, and *Pc5.3*, which were localized to the 22.4–24.6, 53.0–162.6, and 9.7–13.3 Mb regions on Chr05, respectively [31]. Siddique et al. (2019) reported three major QTLs on Chr05, namely, *QTL5.1* (18.7–19.5 Mb), *QTL5.2* (27.3–29.2 Mb), and *QTL5.3* (34.6–37 Mb) that were related to resistance to three *P. capsici* isolates on using combined traditional QTL mapping with GWAS [30]. Here, we performed *P. capsici* resistance QTL analysis of pepper. We detected a major QTL *CQPc5.1* based on a high-density linkage map of F2 plants. *CQPc5.1* was localized to the

17.9–19.4 Mb region on Chr05, with a genetic distance of 33.103–33.448 cM. In an earlier study, Collard et al. (2005) documented that a QTL is only described as "major" when it accounts for >10% of the PVE [52]. In the present study, the phenotypic variance of *CQPc5.1* was 11.58%. In addition, the position of *CQPc5.1* on Chr05 differs from *Pc5.1*, *Pc5.2*, and *Pc5.3*, yet the location of *CQPc5.1* that was identified in this work coincides with that of the earlier determined locus *QTL5.1* [30]. However, the physical location of *CQPc5.1* on the chromosome is closer than that of *QTL5.1*, so we infer that *CQPc5.1* represents a more accurate mapping of resistance to *P. capsici* in pepper.
