Abstract
Some plants in the family of Gramineae accumulate fructan in their tissues as a temporary storage carbohydrate. The accumulation of fructan is associated with freezing tolerance of the plant. Rice is a cold-sensitive plant that is not able to synthesize fructan. We have reported that an increase in cold tolerance at the booting stage was found in transgenic rice expressing wheat fructosyltransferase (Sato et al., Breeding Science Supple, 2005). A rice transformant with 1-SST (sucrose:sucrose 1-fructosyltransferase) accumulates β(2,1) linkage oligomer (DP3-5) and that with 6-SFT (sucrose:fructan 6-fructosyltransferase) accumulates mainly β(2,6) linkage fructan. Cold tolerance of rice seedlings in which fructan accumulates was higher than that of non-transgenic plants. While sucrose content in rice seedlings was remarkably increased by cold treatment, an increase in fructan content and a decrease in the degree of rise in sucrose content were detected in rice seedlings with wheat fructosyltransferase under a low temperature condition.
