Genetic Mapping of a Resistance Locus to Phytophthora sojae in the Korean Soybean Cultivar Daewon

Abstract

Phytophthora root and stem rot reduce soybean yields worldwide. The use of <i>R</i>-gene type resistance is currently crucial for protecting soybean production. The present study aimed to identify the genomic location of a gene conferring resistance to <i>Phytophthora sojae</i> isolate 2457 in the recombinant inbred line population developed by a cross of Daepung × Daewon. Single-marker analysis identified 20 single nucleotide polymorphisms associated with resistance to the <i>P. sojae</i> isolate 2457, which explained ~67% of phenotypic variance. Daewon contributed a resistance allele for the locus. This region is a well-known location for <i>Rps1</i> and <i>Rps7</i>. The present study is the first, however, to identify an <i>Rps</i> gene locus from a major soybean variety cultivated in South Korea. Linkage analysis also identified a 573 kb region on chromosome 3 with high significance (logarithm of odds = 13.7). This genomic region was not further narrowed down due to lack of recombinants within the interval. Based on the latest soybean genome, ten leucine-rich repeat coding genes and four serine/threonine protein kinase-coding genes are annotated in this region, which all are well-known types of genes for conferring disease resistance in crops. These genes would be candidates for molecular characterization of the resistance in further studies. The identified <i>R</i>-gene locus would be useful in developing <i>P. sojae</i> resistant varieties in the future. The results of the present study provide foundational knowledge for researchers who are interested in soybean-<i>P. sojae</i> interaction.