Research on Fructan in Wheat and Temperate Forage Grasses in Japan

In autumn, winter wheat and temperate forage grasses, such as orchardgrass, timothy, and perennial ryegrass, accumulate fructan, which is a kind of fructose-based oligo- and polysaccharide. The fructan content in their crown tissue reaches more than 30% of their dry weight before snow cover, and this increase in fructan content is associated with both the freezing tolerance and the snow mold resistance of winter crops in the northern region of Japan. These crops mainly accumulate the beta(2,6)-linked levan type of fructan, and their structure and composition vary among wheat and grasses. We cloned several kinds of genes encoding fructosyltransferase and fructan exohydrolase from these plants, and analysis of the expression of fructosyltransferase revealed varietal differences in wheat under field conditions and low-temperature responses in grasses. Further investigation of the control of fructan metabolism through molecular biology and genetics should lead to the development of methods for improving the over-wintering ability of these crops.