Fructan synthesis in transgenic tobacco and chicory plants expressing barley sucrose:fructan 6‐fructosyltransferase

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Abstract
We have recently cloned a cDNA encoding sucrose:fructan 6‐fructosyltransferase (6‐SFT), a key enzyme of fructan synthesis forming the β‐2,6 linkages typical of the grass fructans, graminans and phleins [Sprenger et al. (1995) Proc. Natl. Acad. Sci. USA 92, 11652–11656]. Here we report functional expression of 6‐SFT from barley in transgenic tobacco and chicory. Transformants of tobacco, a plant naturally unable to form fructans, synthesized the trisaccharide kestose and a series of unbranched fructans of the phlein type (β‐2,6 linkages). Transformants of chicory, a plant naturally producing only unbranched fructans of the inulin type (β‐2,1 linkages), synthesized in addition branched fructans of the graminan type, particularly the tetrasaccharide bifurcose which is also a main fructan in barley leaves.