Plants often modify their metabolism in order to regain homeostasis and maintain survival in the face of stressful conditions. Here, two species of eucalyptus, E. globulus and E. grandis (adapted and non-adapted to low temperature, respectively), were exposed to either 10 °C or 25 °C over 24 h, and changes in gene expression and metabolite levels were analyzed. The aim of this experiment was to investigate the dynamic of short period changes in the energy metabolism of source (leaves) and sink (stem) tissues in these contrasting species regarding low temperature. We expected to observe a distinct pattern on carbon metabolism and source-to-sink relationship between both species which would be related to their different vegetative responses when facing low temperatures. In that way, E. globulus plants showed a differential expression in leaves and stems of SnRK1 genes system (responsible for energy availability control in plants), that was strongly associated to the changes in carbon metabolism and the main difference between the response when both species face cold. Taken together, the results suggest that low temperatures (10 °C) are able to increase the sink strength of stem tissues and the carbon assimilation in leaves of E. globulus, supporting a higher vegetative growth rate. In E. grandis, on the other hand, exposure to 10 °C promoted a higher consumption of carbon skeletons without better growth rate as a counterpart, suggesting that under cold conditions, these two eucalyptus species differ in the way they coordinate the interaction between the activation of SnRK1 system and primary metabolism in source and sink tissues.

中文翻译：

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一个寒冷的变化：短期的低温暴露如何影响两种桉树叶片和茎的初级代谢

植物通常会改变其新陈代谢，以恢复体内平衡并在面临压力的情况下维持生存。在这里，两种桉树（E. globulus和E. grandis）（分别适应和不适应低温）在24小时内暴露于10°C或25°C，基因表达和代谢产物水平发生变化被分析。本实验的目的是研究与低温有关的这些相对物种中源（叶）和汇（茎）组织能量代谢的短期变化动态。我们期望观察到两个物种之间碳代谢和源库关系的独特模式，这可能与它们在面对低温时的不同营养反应有关。以这种方式，E. globulus植物在SnRK1基因系统的叶子和茎中显示出差异表达（负责植物中的能量利用控制），这与碳代谢的变化和两个物种面对寒冷时响应之间的主要差异密切相关。两者合计，结果表明低温（10°C）能够增加茎组织的沉陷强度和E.globulus叶片中的碳同化作用，从而支持更高的营养生长率。在E. grandis另一方面，暴露于10°C会促进碳骨架的消耗，而没有相应的更好的生长速率，这表明在寒冷条件下，这两种桉树物种在协调SnRK1系统激活之间相互作用的方式上有所不同以及源和汇组织中的主要代谢。