Fructan Content and Fructosyltransferase Activity during Wheat Seed Growth

The objective of this research was to determine the changes in fructan content and the activity of fructosyltransferases during the growth of wheat seeds (Triticum aestivum L. Thell, cv Caldwell). The total fructan content of the seeds decreased significantly during seed growth. The trisaccharide and tetrasaccharide content increased from 6 to 28 days post anthesis (DPA) and then declined, but these changes are not statistically significant. The content or concentration of longer chain polymers did decline significantly (64.55-6.52 milligrams per gram dry weight). Free fructose also decreased significantly during seed growth indicating that the fructose liberated from the decrease in fructan content was utilized by the seed. Sucrose increased significantly from 6 to 12 DPA, then declined significantly from 12 to 28 DPA. Sucrose:sucrose fructosyltransferase activity was greatest from 6 to 12 DPA (averaging 0.16 micromole of fructose transferred per seed per hour), then declined rapidly (0.04 micromole of fructose transferred per seed per hour). The estimated activity of fructan:fructan fructosyltransferase followed a similar pattern. The increase in sucrose concentration and high enzyme activity suggests that fructans were synthesized during the lag phase of seed growth.