Reduction of Trypsin Inhibitor Activity in European Soybean Lines using NGT and Classical Breeding

The soybean is a key source of protein for animal feed due to its high protein content. In Austria and across Europe, the cultivation area is increasing, but it still falls significantly short of demand. One obstacle to direct use is trypsin inhibitors (TI), antinutritional proteins that severely impair digestibility—especially in pigs and poultry. Currently, energy- and cost-intensive processes such as toasting or extrusion are required, which also reduce protein quality. Natural variation for breeding-based reduction of TI activity (TIA) is largely lacking. Knocking out individual genes leads to “proteome rebalancing” and the loss of sulfur-containing amino acids, which are essential for feed quality—meaning classical breeding strategies reach their limits here. The project purses two approaches: (1) precise genome editing using CRISPR/Cas to modify Kunitz and Bowman–Birk genes so that the proteins lose their inhibitory effect while retaining sulfur-containing amino acids; and (2) conventional breeding that utilizes genetic diversity to further reduce TIA. The developed lines will be functionally validated and compared with control plants in terms of TIA, protein content, and protein quality. An accompanying socio-economic analysis evaluates the potential and challenges of biotechnological approaches in plant breeding. The project is carried out by a new consortium consisting of BOKU Vienna and Saatzucht Gleisdorf. The close integration of university research and applied breeding ensures that the results can be transferred into practice. The expected outcomes include novel soybean lines with reduced TIA as starting material for variety breeding, as well as fundamental insights into the regulation of TI proteins. This will enable direct, energy-efficient on-farm use, open up new value creation opportunities for agriculture and the feed industry, and sustainably strengthen regional protein production.