Foxglove aphid, Aulacorthum solani (Kaltenbach), is a Hemipteran insect that infected a wide variety of plants worldwide and caused serious yield losses in crops. The foxglove aphid resistance gene, Raso2 was previously mapped from PI 366121 (Glycine soja Sieb. and Zucc.) to a 26cM marker interval on soybean chromosome 7. The development of additional genetic markers, which are mapped closer to Raso2 were required to accurately position the gene to improve the effectiveness of marker assisted selection. The objective of this study was to narrow down the putative QTL region, which is responsible to foxglove aphid resistance in PI366121 using recently developed high-density 180K Axiom SoyaSNP genotyping array. One hundred and forty one F8-derived F12 recombinant inbred lines developed from a cross of susceptible Williams 82 and resistant PI 366121, were used to generate a fine map of Raso2 interval. The phenotyping of antibiosis and antixenosis was done through choice and no-choice assays with total plant damage (TPD) and primary infestation leaf damage (PLD). The composite interval mapping analysis showed that the physical interval between two flanking makers, which was corresponding to Raso2, was narrowed down to 500kb on the Williams 82 genome assembly (Glyma2.0), instead of 4Mb in the previous report using Goldengate assay. In the Raso2 interval, there are about 60 candidate genes, including 4 of NBS-containing putative R genes. This result could be useful in breeding for new foxglove aphid resistant soybean cultivars.

An important worldwide plant source of dietary protein and oil, modern breeding and improvement of soybean is suffered from a narrow cultivated germplasm relative to other crop species likely because of underuse of wild soybeans as breeding resources. SNP genotyping array is regarded as a promising tool for dissecting wild and cultivated germplasms to find important adaptive genes by high-density genetic mapping and genome-wide association studies (GWAS). Here, we present the establishment of a large soybean SNP array and its use for diversity analysis and high density linkage mapping. More than 4 million high-quality SNPs identified from 16 high-depth and 31 low-depth soybean genome resequencing data were used to select 180,961 SNPs for the AxiomÒ SoyaSNP array. Our validation analysis for a set of 222 diverse soybean lines showed that a total of 171,161markers were of good quality for genotyping. Of the converted SNPs, 82.6% 82.6% SNPs had a marker spacing of less than 9 kb and 17.4% SNPs greater than 9 kb with the 297 inter-SNP spacings of >100 kb and with 812 kb of the largest spacing, thereby suggesting that our array is likely suitable for GWAS of soybean germplasm. This array is being used to construct high-density genetic map in populations generated from intermatings of two cultivated and two wild soybeans, with an objective to confirm large structural variations of chromosomes using the ultra-high-density maps

Soybean is one of the most important crop plants used for seed protein and oil content that has undergone substantial phenotypic and physiological changes during domestication. Thanks to the advent of the next-generation sequencing platforms, genome sequences of many major crop plants including soybean and maize have been unraveled. We have resequenced the genomes of 10 cultivated soybean and 6 accessions of their wild progenitors (Glycine soja) selected from the Korean soybean germplasm to >15 × raw data coverage. We have investigated genome-wide variation patterns in soybean and obtained millions of high-quality single nucleotide polymorphisms (SNPs). Further analyses of the extracted SNPs including population structure analysis, introgressions, linkage disequilibrium, and reduction of diversity are ongoing in order to provide an unprecedented opportunity to finely resolve the domestication history of cultivated soybean. At the same time, we have conducted a comparison study between the Williams 82 soybean reference genome sequence and a genetic map. Here, I will present our current analysis status of the soybean genome resequencing data. Then, I present our recent progresses in the understanding of dynamic genetic features of soybean chromosome revealed by comparison of genetic and sequence-based physical maps in which we have used a portion of our resequencing data to substantiate putative introgression region detected during the construction of a genomewide soybean genetic map.