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

The genomic region cosegregating with the genic male-sterile ms 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 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 locus, was reported. In this study, we constructed a fine map near the ms locus using high-resolution melting (HRM) markers in an F 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 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 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 gene of paprika. To summarize, we developed a cosegregated marker, 32187928-HRM, for marker-assisted selection and identified a strong candidate for the ms gene.