The soybean Kunitz trypsin inhibitor (KTI) protein is responsible for the inferior nutritional quality of unheated or incompletely heated soybean meal. Ti locus controls presence or absence of Kunitz trypsin inhibitor protein. Genetic recombination or tight linkage between Ti locus and Satt228 marker that has been identified to be tightly linked to the Ti locus was detected for marker assisted selection (MAS) using two F2 populations of titi genotype in this study. Two F2 populations were developed from the cross of A29 (KTI protein present, TiTi genotype, AA genotype in Satt228 marker) x Gaechuck#1 and Gaechuck#2 (KTI protein absent, titi genotype, BB genotype in Satt228 marker). Among 31 F2 plants derived from A29 x Gaechuck#1, twenty nine F2 plants show BB genotype that indicates no recombination between Satt228 marker and Ti locus. Only 2 F2 plants show AA genotype that indicates recombination between Satt228 marker and Ti locus. Twenty eight F2 plants derived from A29 x Gaechuck#2 show BB genotype that indicates no recombination between Satt228 marker and Ti locus. Expected genetic ratio between Satt228 marker and Ti locus was 3.6 cM in F2 population.

Leaf chlorophyll-deficient mutants controlled by y9 locus have been observed frequently and are useful in genetic studies in soybean. So far, 19 single recessive gene yellow leaf mutants and one duplicate recessive gene mutant have been described. The y9 type found in T135 is yellow at emergence, becoming greenish-yellow by maturity. Soybean Kunitz trypsin inhibitor protein has been proposed as one of the major antinutritional factor. The absence of Kunitz trypsin inhibitor protein in mature seed is inherited as a recessive allele designated ti. The objective of this research was to confirm independent inheritance between ti gene and y9 gene. The F1 seeds from Gaechuck#1 (Kunitz trypsin inhibitor protein absent, normal leaf type) x C-142 (Kunitz trypsin inhibitor protein present, leaf chlorophyll -deficient) were obtained. F1 seeds obtained were planted in a greenhouse and F1 hybridity was checked on morphological traits. All F2 seeds were planted at field in May 2012. Leaf chlorophyll-deficient trait of F2 individual plants will be recorded at growth stage from field. Presence and absence of Kunitz trypsin inhibitor protein will be checked by SDS-PAGE based on each F₂single plant. Chi-square analysis was used to test the goodness-of-fit of observed ratios with expected ratios for independent assortment or linkage.

Dwarfuess and Kunitz trypsin inhibitor (KTI) protein in soybean is useful traits for basic studies. df2 and ti gene control dwarfness and the expression of Kunitz trypsin inhibitor (KTI) protein in soybean, respectively. The objective of this research was to verify genetic linkage or independent inheritance of df2 and ti loci in soybean. The F2 population was made by cross combination between "Gaechuck#2" (Df2Df2titi genotype, KTI protein absence and a normal growth type) and T210 (df2df2TiTi genotype, a dwarf growth type and KTI protein present). A total of 258 F2 seeds were analyzed for the segregation of KTI protein using SDS-PAGE. And so, 198 F2 plants were recorded for the segregation of dwarfness. The segregation ratio of 3 : 1 for Ti locus (201 Ti : 57 titi) and Df2 locus (143 Df2 : 55 df2df2) was observed. Segregation ratio of 9 : 3 : 3 : 1 (116 TiDf2: 44 Tidf2df2: 27 titiDf2: 11 titidf2df2) between df2 gene and ti gene was observed (x2 =3.53, P = 0.223). These results showed that df2 gene was inherited independently with the ti gene in soybean.

Lectin protein and Kunitz trypsin inhibitor (KTI) protein of mature 　soybean seed are a main antinutritional factor in soybean seed. The Le gene controls a lectin protein and Ti gene controls the KTI protein in soybean. Ti locus has been located on linkage group 9 in the classical linkage map of soybean. Position of Le locus on linkage map was not identified. Genetic relationship between Ti locus and Le locus could be useful in soybean breeding program for the genetic elimination of these factors. The objective of this study was to determine the independent inheritance or linkage between Ti locus and Le locus in soybean seed. Two F2 populations were developed from three parents (Gaechuck#1, T102, and PI548415). The F1 seeds from Gaechuck#1 (titiLeLe) x T102 (TiTilele) and Gaechuck#1 (titiLeLe) x PI548415 (TiTilele) were obtained. The lectin and KTI protein were analysed from F2 seeds harvested from the F1 plants to find independent assortment or linkage between Ti locus and Le locus. The segregation ratios of 3 : 1 for Le locus (129 Le_ : 44 lele) and Ti locus (132 Ti_ : 41 titi) and were observed. The segregation ratios of 9 : 3 : 3 : 1 (95 Le_Li_ : 34 Le_titi: 37 leleTi_ : 7 leletiti) between Le gene and Ti gene in F2 seeds were observed. This data showed that Ti gene was inherited independently with the Le gene in soybean. These results will be helpful in breeding program for selecting the line with lacking both KTI and lectin protein in soybean.