Molecular and Biochemical Characterization of Soybean Genotypes for the Presence of Kunitz Trypsin Inhibitor

Present study was conducted to characterize soybean genotypes for the kunitz trypsin inhibitor at molecular and biochemical level. Genotypes used in the present study included one null KTI soybean line PI542044 (the source of null allele of kunitz trypsin inhibitor being used in soybean breeding programs in India), DSRtiti (homozygous recessive genotype for KTi gene) and seven other elite soybean cultivars. Genomic DNA of all the soybean lines was amplified using gene specific primer for null locus of KTi3 gene and a SSR marker, Satt228 which is tightly linked to Ti locus. Both the markers evidently distinguished between the kunitz trypsin inhibitor free genotypes (PI542044, and DSRtiti) and cultivars with kunitz trypsin inhibitor (Bragg, VL Bhatt, SL-688, SL-525, PS-1042, SL-744 and Dadacha respectively). The results presented show the utility of gene specific as well as SSR maker for identification of kunitz trypsin inhibitor free genotypes developed from PI542044. Kunitz trypsin inhibitor protein appeared as 21.5 kDa protein band as revealed by SDS-PAGE. A perfect correspondence was observed at DNA and protein level in terms of kunitz trypsin inhibitor which was further validated by assaying the trypsin inhibitor activity in which kunitz trypsin inhibitor free genotypes showed very low trypsin inhibitor activity.Therefore, the results clearly indicate that the either the gene specific marker used in the present study or linked SSR marker Satt228 can be efficiently used in the selection of target plants carrying null allele of kunitz trypsin inhibitor in the marker assisted breeding for development of kunitz trypsin inhibitor free soybean in our country.