Sucrose is nutritionally useful and fully digested by monogastric animals, but RFOs are antinutritional and not digested in animal’s gut. Currently, commodity soybean seed contains 3.0-5.2% sucrose, 0.8 – 1.1% raffinose and 3.0–4.5% stachyose. This project aims to increase sucrose content over 10% and at the same time reduce RFOs boost the nutritional and economical value of soybean meal. Using innovative mutational breeding and gene-editing technology, we are stacking novel genes and applying gene-editing technology to boost sucrose content 10% or higher. In addition to novel genes, we are targeting well-characterized raffinose and stachyose synthase (RS/STS) and myo-inositol-3-phosphate synthase (MIPS) to efficiently generate lines with high-sucrose and low-RFOs. We have successfully identified several mutant lines with high sucrose content (7.3 – 10 %) using forward and reverse genetics. Importantly, we initiated gene-editing strategy to target known as well as novel genes and developed several CRISPR knockout mutant lines which will be characterized in FY2024.

Soybean meal protein serves as the primary source of metabolized energy in the diets of poultry and livestock. In addition to protein content, the desirability of higher soluble carbohydrate levels (specifically sucrose) and lower levels of raffinose and stachyose (members of the raffinose family oligosaccharides, RFOs) is a critical consideration for enhancing animal digestibility. These carbohydrate components are pivotal in determining the nutritional and economic value of soybean-based animal feed and food products. Sucrose is nutritionally beneficial and can be fully digested by monogastric animals, while RFOs are considered antinutritional as they remain undigested in the animal's gastrointestinal tract. At present, conventional soybean seeds typically contain sucrose levels ranging from 3.0% to 5.2%, with select high-sucrose variants containing up to 6.1% sucrose. Our research has led to the identification of multiple mutant soybean lines that exhibit sucrose content exceeding 8% in their seeds. These newfound sources hold the potential to expedite soybean breeding efforts aimed at enhancing the overall nutritional quality of soybean-based feed and food. Notably, we have successfully developed gene-edited lines using advanced CRISPR/Cas9 technology to combine high sucrose and low RFO traits, further advancing the potential for improved soybean varieties.