Down-regulation of galactinol synthesis in oilseed Brassica napus leads to significant reduction of antinutritional oligosaccharides

The utility of defatted seed meal from many crops such as canola (Brassica napus L.) is limited by the presence of antinutritional factors, including sucrose galactosides, raffinose, and stachyose. Anaerobic breakdown of these sugars in the digestive tract of livestock is a major source of production of farm gases. In this report, the gene encoding galactinol synthase was isolated from B. napus and reintroduced into the same species in an antisense orientation to limit the production of galactinol, an important intermediate in the biosynthesis of raffinose and stachyose. This approach substantially reduced the accumulation of galactinol and stachyose in mature transgenic canola seed. Substantial changes in the mRNA levels of galactinol synthase and several sugar-related genes were also observed.