Kompetitive Allele-Specific PCR Marker Development and Quantitative Trait Locus Mapping for Bakanae Disease Resistance in Korean Japonica Rice Varieties

High-throughput molecular markers with high genotyping accuracy will be helpful for genetic analysis, mapping of interesting genes, and rice breeding program. To develop high-throughput and cost-effective molecular markers for Korean japonica rice varieties, which are closely-related genetically, we designed kompetitive allele-specific polymerase chain reaction (KASP) assays from the sequence data of 13 Korean japonica rice varieties. Of the 504 new KASP assays, 371 (73.6%) showed polymorphisms among the tested varieties. In addition to the 400 previously developed KASP markers, this resulted in 771 KASP markers being applicable for Korean japonica rice varieties. These KASP markers were used to map the quantitative trait loci (QTLs) for rice bakanae disease (BD) resistance. From the results of QTL mapping and determination of the mortality rate of BD in two F2:F3 populations, a major QTL, qFfR1-1, and a novel QTL, qFfR6, were revealed on chromosome 1 in the Junam/Nampyeong F2:F3 population and on chromosome 6 in the Saenuri/Nampyeong F2:F3 population, respectively. Further, the insertion/deletion markers in the qFfR1-1 region were developed to select BD-resistant japonica rice varieties. The 771 developed KASP markers will accelerate the molecular breeding in Korean japonica rice varieties, and the detected QTLs will be helpful in identifying candidate genes for BD resistance.