Functional characterization of a sucrose:fructan 6-fructosyltransferase of the cold-resistant grass Bromus pictus by heterelogous expression in Pichia pastoris and Nicotiana tabacum and its involvement in freezing tolerance.
الكلمات الدالة
نبذة مختصرة
We have previously reported the molecular characterization of a putative sucrose:fructan 6-fructosyltransferase (6-SFT) of Bromus pictus, a graminean species from Patagonia, tolerant to cold and drought. Here, this enzyme was functionally characterized by heterologous expression in Pichia pastoris and Nicotiana tabacum. Recombinant P. pastoris Bp6-SFT showed comparable characteristics to barley 6-SFT and an evident fructosyltransferase activity synthesizing bifurcose from sucrose and 1-kestotriose. Transgenic tobacco plants expressing Bp6-SFT, showed fructosyltransferase activity and fructan accumulation in leaves. Bp6-SFT plants exposed to freezing conditions showed a significantly lower electrolyte leakage in leaves compared to control plants, indicating less membrane damage. Concomitantly these transgenic plants resumed growth more rapidly than control ones. These results indicate that Bp6-SFT transgenic tobacco plants that accumulate fructan showed enhanced freezing tolerance compared to control plants.