Fructan biosynthesis in excised leaves of Lolium temulentum L.

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Abstract
SUMMARY: Following the initiation of soluble carbohydrate accumulation in excised illuminated leaves of Lolium temulentum L., extractable sucrose: sucrose fructosyl transferase activity rose concomitant with the onset of fructan synthesis Extractable enzyme activity was sufficient to account for rates of fructan accumulation in vivo The major trisaccharide products of transferase activity in vitro were isokestose and kestose. This differed from the patterns of trisaccharide accumulation in vivo, where isokestose and neokestose predominated.Excised leaves treated with inhibitors of protein synthesis and of RNA metabolism accumulated water‐soluble carbohydrate at similar rates to control tissue, but did not convert sucrose into fructan. Inhibitor treatment also prevented increase in extractable sucrose: sucrose fructosyl transferase activity, suggesting that initiation of fructan biosynthesis was mediated by altered patterns of gene expression. These results are discussed in relation to the control of the synthesis of the oligofructosides characteristic of this tissue.