Identification of soybean Kunitz-free progenies in full-sib crossing

Kunitz trypsin inhibitor (KTI) is part of the anti-nutritional complex present in soybeans. Soybean grain without KTI can be used in the diet of non-ruminants without prior heat treatment. In order to obtain soybean lines with reduced content of anti-nutrients in the grain, in the first place without KTI, we crossed the adapted genotype of standard grain quality (variety Kador) with the genotype without KTI, less adapted to our growing conditions (variety Kunitz). A segregating generation was obtained from which the three most productive F3 lines, heterozygous for the presence of KTI, were selected for the new crossing cycle. Two combinations of full-sib (FS) crosses with different numbers of successfully crossed plants were realized. Determination of the presence of KTI in progeny developed from selected lines originating from Kunitz x Kador crosses and their combinations of FS crosses was performed using protein markers on a native polyacrylamide gel. Based on the electrophoregram, it was noticed that the bands corresponding to the KTI position are not of the same intensity. The analysis was done from a group sample, so it is possible that the sample contains grains with and without KTI. Ten progenies of maternal lines and five progenies of FS crosses without a band corresponding to the KTI position were identified on the electrophoregram. A total of four progenies with grain yield per plant at the level and better than the more productive parent can be considered promising for the further selection process.