Genetic Mapping of the Powdery Mildew Resistance (PMR1) Gene in Pepper (Capsicum annuum)

Abstract

Pepper powdery mildew caused by Leveillula taurica is considered to be the major fungal disease of peppers (Capsicum annuum) grown in greenhouse. Previous studies have demonstrated that powdery mildew resistance has a complex mode of inheritance. In the present study, a novel powdery mildew resistant gene, PMR1 introgressed in a resistant breeding line, VK515 R was investigated using the F2:3 families derived from a cross between the resistant parent VK515 R and the susceptible parent VK515 S. Genetic analysis of the VK515 F2:3 families showed a single dominant inheritance of the resistance. Genetic mapping showed that the PMR1 locus is located on pepper chromosome 0 in a 4 Mb-region between CZ2_11628 and HRM4.1.6 markers. No recombinants were observed in 4 Mb-region, one SCAR marker and five SNP markers were found to be 0 cM apart from the PMR1 locus, which could be due to the suppressed recombination, as revealed by the GBS analysis. In addition, comparison of species-specific InDel markers as well as GBS derived SNP markers indicated that C. baccatum as a possible source of alien introgression of powdery mildew resistance in VK515 R. The molecular markers developed herein especially helpful in marker-assisted selection in pepper breeding programs against powdery mildew resistance.