Journal Article

Plant fructans in stress environments: emerging concepts and future prospects

Ravi Valluru and Wim Van den Ende

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 11, pages 2905-2916
Published in print August 2008 | ISSN: 0022-0957
Published online July 2008 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/ern164
Plant fructans in stress environments: emerging concepts and future prospects

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Plants are sessile and sensitive organisms known to possess various regulatory mechanisms for defending themselves under stress environments. Fructans are fructose-based polymers synthesized from sucrose by fructosyltransferases (FTs). They have been increasingly recognized as protective agents against abiotic stresses. Using model membranes, numerous in vitro studies have demonstrated that fructans can stabilize membranes by direct H-bonding to the phosphate and choline groups of membrane lipids, resulting in a reduced water outflow from the dry membranes. Inulin-type fructans are flexible random-coiled structures that can adopt many conformations, allowing them to insert deeply within the membranes. The devitrification temperature (Tg) can be adjusted by their varying molecular weights. In addition, above Tg their low crystallization rates ensure prolonged membrane protection. Supporting, in vivo studies with transgenic plants expressing FTs showed fructan accumulation and an associated improvement in freezing and/or chilling tolerance. The water-soluble nature of fructans may allow their rapid adaptation as cryoprotectants in order to give optimal membrane protection. One of the emerging concepts for delivering vacuolar fructans to the extracellular space for protecting the plasma membrane is vesicle-mediated, tonoplast-derived exocytosis. It should, however, be noted that natural stress tolerance is a very complex process that cannot be explained by the action of a single molecule or mechanism.

Keywords: Abiotic stress; freezing tolerance; fructan; inulin; membrane stabilization

Journal Article.  7409 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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