Photosynthesis and carbohydrate metabolism of higher plants need to be tightly regulated to prevent tissue damage during environmental changes. The intracellular position of chloroplasts changes due to a changing light regime. Chloroplast avoidance and accumulation response under high and low light, respectively, are well known phenomena, and deficiency of chloroplast movement has been shown to result in photodamage and reduced biomass accumulation. Yet, effects of chloroplast positioning on underlying metabolic regulation are less well understood. Here, we analysed photosynthesis together with metabolites and enzyme activities of the central carbohydrate metabolism during cold acclimation of the chloroplast unusual positioning 1 (chup1) mutant of Arabidopsis thaliana. We compared cold acclimation under ambient and low light and found that maximum quantum yield of PSII was significantly lower in chup1 than in Col-0 under both conditions. Our findings indicated that net CO₂ assimilation in chup1 is rather limited by biochemistry than by photochemistry. Further, cold-induced dynamics of sucrose phosphate synthase differed significantly between both genotypes. Together with a reduced rate of sucrose cycling derived from kinetic model simulations our study provides evidence for a central role of chloroplast positioning for photosynthetic and metabolic acclimation to low temperature.

高等植物的光合作用和碳水化合物代谢需要受到严格调控，以防止环境变化期间的组织损伤。由于光照条件的变化，叶绿体的细胞内位置会发生变化。分别在高光和低光下的叶绿体回避和积累反应是众所周知的现象，叶绿体运动的不足已被证明会导致光损伤和生物量积累减少。然而，叶绿体定位对潜在代谢调节的影响还不太清楚。在这里，我们分析了拟南芥叶绿体异常定位1（chup1）突变体冷驯化过程中的光合作用以及中央碳水化合物代谢的代谢产物和酶活性。. 我们比较了环境和弱光下的冷驯化，发现在两种条件下，chup1中 PSII 的最大量子产率显着低于Col-0。我们的研究结果表明，chup1中的净 CO ₂同化受生物化学而非光化学的限制。此外，冷诱导的蔗糖磷酸合酶动力学在两种基因型之间显着不同。连同源自动力学模型模拟的蔗糖循环速率降低，我们的研究为叶绿体定位对光合作用和代谢适应低温的核心作用提供了证据。