*3.4. Phenotypic Analysis of P. capsici Resistance*

In 2008, the disease indices (DIs) of 150 F2 populations were determined (Table 5). The highest DI value was recorded in the susceptible 1287 (84.3), while the lowest ID value was recorded in the resistance parent PI201234 (7.9). The DI values of the F2 population varied between 0.00 and 100. The average DI value of the F2 population was 47.2. The variation was 0.75, and skewness and kurtosis value of the DI in the F2 population was small, indicating that the population was suitable for QTL identification.



## *3.5. QTL Mapping of P. capsici Resistance*

In present study, the maximum LOD value of 6.972 was used as the threshold to determine the existence of QTL. Based on the high-density genetic map, a single major QTL for the *P. capsici* resistance trait was identified in the F2 population and designated as *CQPc5.1* (Table 6, Figure 4), which explained 11.76% of the observed phenotypic variance. *CQPc5.1* was localized in 17.9–19.4 Mb on Chr05, which encompassed a genetic distance of about 0.35 cM, as well as a physical distance of about 1.47 Mb on Chr05 (Table 6).


**Table 6.** Quantitative trait locus (QTL) analysis of the *P. capsici* resistance trait in F2 populations.

Note: LOD, logarithm of odds. Maximum LOD score (QTL peak). ADD, additive effects. DOM, dominance effects. PVE, phenotypic variance explained.
