Strategies of low temperature survival in Arabidopsis thaliana

在“拟南芥低温生存策略”项目的第一年，我们通过非水相区室分离和GC-MS定量代谢分析相结合的方法，证明了低温驯化过程中代谢物的多个亚细胞重新分配。对淀粉代谢缺陷和蔗糖周转强烈降低的代谢突变体pgm和spsa 1的研究，分别揭示了强有力的证据表明，一个质体协会的棉子糖，胞质脯氨酸和可能的转移还原当量和/或中间体之间的光蒸腾质体和线粒体是相关的耐冻性。在项目的第二阶段，我们希望将这些分析扩展到代表广泛抗冻性的拟南芥天然种质。这将允许绘制具有亚细胞分辨率的冷适应的“代谢图”。特别是，我们希望跟踪我们获得的证据，即天冬氨酸/苹果酸和谷氨酸/ 2-氧代戊二酸的交换用于转移还原当量，以及鸟氨酸/瓜氨酸用于转移线粒体和质体之间的光呼吸中间产物。与此同时，冷冻事件的热成像分析将揭示拟南芥在一般或特定的自然加入是否能够容忍冰形成在细胞内空间，以及是否某些代谢模式与这种能力。应通过改变相关代谢物的含量来改变抗冻性。

In the first year working on the project "Strategies of low temperature survival in Arabidopsis thaliana", we could prove multiple sub-cellular re-allocations of metabolites during cold acclimation by combining the methods of non-aqueous fractionation of compartments and quantitative metabolic profiling using GC-MS. Investigations on the metabolic mutants pgm and spsa1 that are defective in starch metabolism and strongly reduced in sucrose turnover, respectively, revealed strong evidence that a plastidial association of raffinose, cytosolic prolin and possibly the transfer of reducing equivalents and / or intermediates of phototranspiration between plastids and mitochondria are relevant for freezing tolerance. In a second phase of the project we want to expand these analyses to natural accessions of Arabidopsis that represent a broad spectrum of freezing tolerance. This shall allow drawing a "metabolic map" of cold acclimation with sub-cellular resolution. In particular, we want to follow up the evidence we obtained for exchange of aspartate / malate and glutamate / 2-oxo-glutarate for the transfer of reducing equivalents as well as ornithine / citrulline for the transfer of intermediates of photorespiration between mitochondria and plastids. n parallel, thermographic analysis of freezing events shall reveal whether Arabidopsis in general or specific natural accessions are able to tolerate ice formation in intracellular spaces, and whether certain metabolic patterns correlate with this ability. Modification of the content of relevant metabolites shall be used to alter freezing tolerance.