Transgenic perennial ryegrass plants expressing wheat fructosyltransferase genes accumulate increased amounts of fructan and acquire increased tolerance on a cellular level to freezing

The accumulation of fructan in grasses during autumn is linked to winter hardiness. Genetic manipulation of the accumulation of fructan could be an important molecular breeding strategy for the improvement of winter hardiness in grasses. We produced transgenic perennial ryegrass (Lolium perenne) plants that overexpress wheat fructosyltransferase genes, wft1 and wft2, which encode sucrose-fructan 6-fructosyltransferase (6-SFT) and sucrose-sucrose 1-fructosyltransferase (1-SST), respectively, under the control of CaMV 35S promoter using a particle bombardment-mediated method of transformation. Significant increases in fructan content were detected in the transgenic perennial ryegrass plants. A freezing test using the electrical conductivity method indicated that transgenic plants that accumulated a greater amount of fructan than non-transgenic plants have increased tolerance on a cellular level to freezing. The results suggest that the overexpression of the genes involved in fructan synthesis serves as a novel strategy to produce freezing-tolerant grasses. (C) 2004 Elsevier Ireland Ltd. All rights reserved.