Fine mapping of the genic male-sterile ms ₁ gene in Capsicum annuum L

The genomic region cosegregating with the genic male-sterile ms ₁ gene of Capsicum annuum L. was delimited to a region of 869.9 kb on chromosome 5 through fine mapping analysis. A strong candidate gene, CA05g06780, a homolog of the Arabidopsis MALE STERILITY 1 gene that controls pollen development, was identified in this region. Genic male sterility caused by the ms ₁ gene has been used for the economically efficient production of massive hybrid seeds in paprika (Capsicum annuum L.), a colored bell-type sweet pepper. Previously, a CAPS marker, PmsM1-CAPS, located about 2-3 cM from the ms ₁ locus, was reported. In this study, we constructed a fine map near the ms ₁ locus using high-resolution melting (HRM) markers in an F₂ population consisting of 1118 individual plants, which segregated into 867 male-fertile and 251 male-sterile plants. A total of 12 HRM markers linked to the ms ₁ locus were developed from 53 primer sets targeting intraspecific SNPs derived by comparing genome-wide sequences obtained by next-generation resequencing analysis. Using this approach, we narrowed down the region cosegregating with the ms ₁ gene to 869.9 kb of sequence. Gene prediction analysis revealed 11 open reading frames in this region. A strong candidate gene, CA05g06780, was identified; this gene is a homolog of the Arabidopsis MALE STERILITY 1 (MS1) gene, which encodes a PHD-type transcription factor that regulates pollen and tapetum development. Sequence comparison analysis suggested that the CA05g06780 gene is the strongest candidate for the ms ₁ gene of paprika. To summarize, we developed a cosegregated marker, 32187928-HRM, for marker-assisted selection and identified a strong candidate for the ms ₁ gene.