Studies on Fructan Accumulation in Wheat(Triticum aestivum L.). IV. Fructan accumulation under cold treatments and its varietal difference in relation to the activities of sucrose-sucrose fructosyl transferase and fructan exohydrolase.

Abstract

The mechanisms of fructan accumulation by changes in sucrose-sucrose fructosyl transferase (SST; EC 2.4.1.99) and fructan exohydrolase (FEH; EC 3.2.1.80) under cold treatments (2°C, 6°C) were investigated using varieties of wheat (Triticum aestivum L. cv. Norin 61 and Yukichabo) differing in fructan accumulation. Fructan concentration increased with the increase in SST activity and decrease in FEH activity under cold treatments. The acumulation of fructans was accelerated with high activity of SST at 2°C treatment, suggesting the participation of SST in fructan accumulation. The variety of Norin 61, which has lower fructan accumulation, contained higher activity of FEH, and the fructan concentration of Norin 61 decreased with increasing FEH activity from the 10th day under 6°C treatment, suggesting that the varietal difference in fructan accumulation is affected largely by the level of FEH activity. The relationship between fructan accumulation and growth habit in the varieties is discussed.