Powdery mildew disease caused by Leveillula taurica is a serious fungal threat to greenhouse pepper production. In contrast to most epiphytic powdery mildew species, L. taurica is an endophytic fungus which colonizes in the mesophyll tissues of the leaf. In the genus Capsicum, several studies have been conducted to identify resistance sources to L. taurica. In previous studies, five quantitative trait loci (QTLs) for powdery mildew resistance have been identified. An F2 population derived from self-pollination of the commercial cultivar Capsicum annuum ‘PM Singang’ was used for genetic analysis of powdery mildew resistance. Resistance of the F2 plants was tested under the natural environmental conditions. Sporulation intensity on infected leaves was used as a disease scale to assign resistance levels to plants, where 0-5% is Resistant, 6-15% Moderate resistant and 16-100% Susceptible. A total of 83 F2 plants were evaluated for resistance. The results showed that 59 plants were resistant, 10 susceptible and 14 moderately resistant. If we consider MR as S, segregation ratio fitted to a single dominant resistance gene model. In the future study, closely linked molecular marker will be developed and tested to locate this gene. The developed marker will be used to identify the powdery mildew resistance gene.

• Jinkwan Jo(Department of Plant Science, Plant Genomics and Breeding Institute, and Vegetable Breeding Research Center, College of Agriculture and Life Sciences, Seoul National University)
• Gyung Ja Choi(Research Center for Biobased Chemistry, Korea Research Institute of Chemical Technology)
• Jin-Kyung Kwon(Department of Plant Science, Plant Genomics and Breeding Institute, and Vegetable Breeding Research Center, College of Agriculture and Life Sciences, Seoul National University)
• Byoung-Cheorl Kang(Department of Plant Science, Plant Genomics and Breeding Institute, and Vegetable Breeding Research Center, College of Agriculture and Life Sciences, Seoul National University)