Department of Plant Biotechnology, Institute of Biology, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
Planta. 2011 Sep;234(3):477-86. doi: 10.1007/s00425-011-1413-0. Epub 2011 May 1.
A role of non-reducing sugars like sucrose and raffinose in the protection of plant cells against damage during freezing has been proposed for many species, but reports on physiological effects are conflicting. Non-aqueous fractionation of mesophyll cell compartments in Arabidopsis thaliana was used to show that sucrose and raffinose accumulate in plastids during low temperatures, pointing to a physiological role in protecting the photosynthetic apparatus. Comparing a previously described raffinose synthase (RS) mutant of A. thaliana with its corresponding wild type, accession Col-0, revealed that a lack of raffinose has no effect on electrolyte leakage from leaf cells after freeze-thaw cycles, supporting that raffinose is not essential for protecting the plasma membrane. However, in situ chlorophyll fluorescence showed that maximum quantum yield of PS II photochemistry (F (v)/F (m)) and other fluorescence parameters of cold acclimated leaves subjected to freeze-thaw cycles were significantly lower in the raffinose synthase mutant than in the corresponding wild type, indicating that raffinose is involved in stabilizing PS II of cold acclimated leaf cells against damage during freezing.
已提出非还原糖（如蔗糖和棉子糖）在许多物种的植物细胞免受冷冻损伤中的保护作用，但关于其生理作用的报告存在矛盾。通过对拟南芥的质体细胞区室进行非水相分离，表明蔗糖和棉子糖在低温下积累在质体中，这表明它们在保护光合作用装置方面具有生理作用。比较拟南芥先前描述的棉子糖合酶（RS）突变体与其相应的野生型 Col-0，发现缺乏棉子糖对冻融循环后叶片细胞的电解质渗漏没有影响，这支持棉子糖不是保护质膜所必需的。然而，原位叶绿素荧光表明，在冻融循环处理下，经冷驯化的叶片的 PS II 光化学的最大量子产量（F(v)/F(m)）和其他荧光参数在棉子糖合酶突变体中明显低于相应的野生型，这表明棉子糖参与稳定 PS II 以防止冷驯化的叶片细胞在冷冻过程中受到损伤。
