Fructan metabolism in tall fescue calli under different environmental condition
Several grasses usually accumulate high levels of fructans at low temperature or in the presence of high sugar supply. Fructans enhance plant resistance in adverse environmental conditions thanks to their vacuolar localization which allow osmotic adjustments. Tall fescue calli do not show mature vacuoles due to its anatomic characteristics, and these in vitro cultures can provide more knowledge about the fructan rule in unspecialized tissues especially during stress conditions. The aim of this study was to evaluate the sugar metabolism in embryogenic calli of tall fescue fed with different sucrose concentrations (0, 50 or 100 mM) during growth culture, kept at “control” or “cold” temperatures (23 or 4°C, respectively). In the presence of sucrose (50 or 100 mM), embryogenic calli accumulated fructans under control conditions. On the other hand, the accumulation is inhibited by the simultaneously sugar supply and cold treatment while invertase activity increased. From our data, cold temperature and high sucrose concentration seemed to be negatively correlated in the fructans biosynthetic pathway in tall fescue in vitro cultures.
Key words: Cold, Festuca arundinacea, invertase, sucrose:sucrose fructosyltransferase (SST), sugars.