Validation of molecular markers for the Kunitz trypsin inhibitor protein in soybean (Glycine max L. merr.)

Soybean (Glycine max L.) is a major source of plant proteins, but its use is restricted by anti-nutritional factors such as the Kunitz trypsin inhibitor (KTI). Eliminating KTI improves protein digestibility and reduces processing costs in food and feed production. This study aimed to use simple sequence repeat (SSR) markers in marker-assisted selection (MAS) for KTI-free soybean genotypes developed at the Maize Research Institute ?Zemun Polje? (MRIZP). The new breeding line L003, derived from a cross between the standard line L584 and the KTI-free cultivar ?Laura,? was analyzed. Fifty-two F? seeds were screened with SSR markers Satt228 and Satt409, and the observed results were validated by detecting possible KTI protein by polyacrylamide gel electrophoresis (PAGE). In all L003 plants, homozygosity for the KTI-null genotype was observed by both SSR markers. Biochemical analysis showed the absence of the 21.5 kDa KTi protein band in L003, while the control genotype ?Lidija? with the dominant allele (TiTi) expressed KTI. Those results demonstrate a strong correlation between SSR marker profiles and the presence of KTI protein. Our results showed that both Satt228 and Satt409 are reliable tools for foreground selection in MAS, supporting the efficient development of KTI-free soybean cultivars. These results promote breeding strategies to develop nutritionally improved soybean varieties for food and feed industries without the necessity of thermal inactivating KTI.