Soybean seeds contain high amounts of isoflavones that display biological effects and isoflavone content of soybean seed can vary by year, environment, and genotype. Objective of this study was to identify quantitative trait loci that underlie isoflavone content in soybean seeds. The study involved 85 F2 populations derived from Korean soybean cultivar 'Kwangkyo' and wild type soybean 'IT182305' for QTL analysis associated with isoflavone content. Isoflavone content of seeds was determined by HPLC. The genetic map of 33 linkage groups with 207 markers was constructed. The linkage map spanned 2,607.5 cM across all 33 linkage groups. The average linkage distance between pair of markers among all linkage groups was 12.6 cM in Kosambi map units. Isoflavone content in F2 generations varied in a fashion that suggested a continuous, polygenic inheritance. Eleven markers (4 RAPD, 3 SSR, 4 AFLP) were significantly associated with isoflavone content. Only two markers, Satt419 and CTCGAG3 had F-tests that were significant at P<0.01 in F2 generation for isoflavone content. Interval mapping using the F2 data revealed only two putative QTLs for isoflavone content. The peak QTL region on linkage group 3, which was near OPAG03c, explained 14~% variation for isoflavone content. The peak QTL region on linkage group 5, which was located near OPN14 accounted for 35.3~% variation for isoflavone content. Using both Map-Maker-QTL (LOD~geq2.0) and single-factor analysis (P~leq0.05) , one marker, CTCGAG3 in linkage group 3 was associated with QTLs for isoflavone content. This information would then be used in identification of QTLs for isoflavone content with precision

Soybean is a major source of protein meal in the world. Kunitz trypsin inhibitor (KTI) protein is responsible for the inferior nutritional quality of unheated or incompletely heated soybean meal. The objective of this research was to identify RAPD markers linked to KTI protein allele using bulked segregant analysis. Cultivar Jinpumkong2 (TiTi) was crossed with C242 (titi, absence of KTI protein) and F. seeds were planted. The F1 . plants were grown in the greenhouse to produce F2 seeds. Each F2 seed from F1 . plants was analysed electrophoretically to determine the presence of the KTI protein band. The present and absent bulks contained twenty individuals each, which were selected on the basis of the KTI protein electrophoresis, respectively. Total 94 F2 individuals were constructed and 1,000 Operon random primers were used to identify RAPD primers linked to the Ti locus. The presence of KTI protein is dominant to the lack of a KTI protein and Kunitz trypsin inhibit protein band is controlled by a single locus. Four RAPD primers (OPAC12, OPAR15, OPO12, and OPC08) were linked to the Ti locus. RAPD primer OPO12 was linked to Ti locus, controlling kunitz trypsin inhibitor protein at a distance of 16.0 cM. This results may assist in study of developing fine map including Ti locus in soybean.

Genetic linkage maps serve the plant geneticist in a number of ways, from marker assisted selection in plant improvement to map-based cloning in molecular genetic research. Genetic map based upon DNA polymorphism is a powerful tool for the study of qualitative and quantitative traits in crops. The objective of this study was to develop genetic linkage map of soybean using the population derived from the cross of Korean soybean cultivar 'Kwangkyo, and wild accession 'IT182305'. Total 1,000 Operon random primers for RAPD marker, 49 combinations of primer for AFLP marker, and 100 Satt primers for SSR marker were used to screen parental polymorphism. Total 341 markers (242 RAPD, 83 AFLP, and 16 SSR markers) was segregated in 85 ~textrmF2 population. Forty two markers that shown significantly distorted segregation ratio (1:2:1 for codominant or 3:1 for domimant marker) were not used in mapping procedure. A linkage map was constructed by applying the computer program MAPMAKER/EXP 3.0 to the 299 marker data with LOD 4.0 and maximum distance 50 cM. 176 markers were found to be genetically linked and formed 25 linkage groups. Linkage map spanned 2,292.7 cM across all 25 linkage groups. The average linkage distance between pair of markers among all linkage groups was 13.0 cM. The number of markers per linkage group ranged from 2 to 55. The longest linkage group 3 spanned 967.4 cM with 55 makers. This map requires further saturation with more markers and agronomically important traits will be joined over it.