FIGURE 1.

Representation of the various fructan-types and suggested biosynthesis routes in developing barley grain tissues. A spatiotemporally specific coordinated biosynthesis of oligofructans has been observed for barley grains. The pathway in blue illustrates the major route of biosynthesis during the prestorage phase and red indicates the major route during the storage phase. During the prestorage phase a high transcript level for 1-SST and 6-SFT was observed for the endosperm leading to an accumulation of 6-kestose and bifurcose (indicated in blue). With transition to the storage phase a transcriptional switch was observed resulting in high transcript levels of 1-SST in the nucellar projection (NP). 1-FFT was found to be exclusively expressed in the NP during the storage phase. Induction of the inulin-type oligofructan biosynthesis pathway led to high amounts of 1-kestose and nystose accumulated in the endosperm cavity (indicated in red). Oligofructans of the neo-series were not detected in developing barley grains. Abbreviations are: 1-FFT, fructan:fructan 1-fructosyltransferase; 1-SST, sucrose:sucrose 1-fructosyl-transferase; 6-SFT, sucrose:fructan 6-fructosyltransferase; 6G-FFT, fructan:fructan 6G-fructosyltransferase.