Plant fructans in stress environments: emerging concepts and future prospects
- Publication Type
- Journal contribution
- Authors
- Valluru, R.; Van den Ende, W.
- Year of publication
- 2008
- Published in
- Journal of Experimental Botany
- Band/Volume
- 59/
- Series/labeling
- 11
- Page (from - to)
- 2905-2916
AbstractPlants are sessile and sensitive organisms known topossess various regulatory mechanisms for defendingthemselves under stress environments. Fructans arefructose-based polymers synthesized from sucrose byfructosyltransferases (FTs). They have been increasinglyrecognized as protective agents against abioticstresses. Using model membranes, numerous in vitrostudies have demonstrated that fructans can stabilizemembranes by direct H-bonding to the phosphate andcholine groups of membrane lipids, resulting in a reducedwater outflow from the dry membranes. Inulintypefructans are flexible random-coiled structures thatcan adopt many conformations, allowing them toinsert deeply within the membranes. The devitrificationtemperature (Tg) can be adjusted by their varyingmolecular weights. In addition, above Tg their lowcrystallization rates ensure prolonged membrane protection.Supporting, in vivo studies with transgenicplants expressing FTs showed fructan accumulationand an associated improvement in freezing and/orchilling tolerance. The water-soluble nature of fructansmay allow their rapid adaptation as cryoprotectants inorder to give optimal membrane protection. One of theemerging concepts for delivering vacuolar fructans tothe extracellular space for protecting the plasmamembrane is vesicle-mediated, tonoplast-derived exocytosis.It should, however, be noted that naturalstress tolerance is a very complex process that cannotbe explained by the action of a single molecule ormechanism.