Feedback Inhibition of Starch Degradation in Arabidopsis Leaves Mediated by Trehalose 6-Phosphate
Feedback Inhibition of Starch Degradation in Arabidopsis Leaves Mediated by Trehalose 6-Phosphate
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DOI：
10.1104/pp.113.226787
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发表时间：
2013-11-01
期刊：
影响因子：
7.4
通讯作者：
Lunn, John Edward
中科院分区：
文献类型：
--
作者：
Martins, Marina Camara Mattos;Hejazi, Mahdi;Lunn, John Edward
许多植物在白天在叶片中积累大量的淀粉储备，并在夜间重新动员它们，为维持和生长提供碳和能量。在本文中，我们探讨了糖信号代谢产物，海藻糖-6-磷酸（Tre 6P），在调节拟南芥（拟南芥）叶片中的临时淀粉的积累和营业额的作用。白天乙醇诱导的海藻糖磷酸合酶过表达使Tre 6P水平增加了11倍。在一天的中间，淀粉积累的速率有一个短暂的增加，但这与ADP-葡萄糖焦磷酸化酶的还原活化无关。夜间Tre 6P增加2至3倍导致淀粉降解的显著抑制。麦芽糖和麦芽三糖没有积累，表明Tre 6P影响叶绿体中淀粉降解途径的早期步骤。从诱导的植物中分离的淀粉颗粒具有较高的正磷酸盐含量比颗粒从noninduced控制植物，无论是与磷酸化-去磷酸化循环，这是必不可少的有效的淀粉分解或抑制淀粉水解β-淀粉酶的中断一致。叶的非水分馏表明，Tre 6P主要位于细胞质中，估计在体内Tre 6P浓度为4至7 μ M的细胞质中，0.2至0.5 μ M的叶绿体中，和0.05 μ M的液泡中。有人提出，Tre 6P是一个组件的信号通路，介导的反馈调节淀粉分解蔗糖，潜在的连接淀粉周转到需求蔗糖在夜间生长的水槽器官。
Many plants accumulate substantial starch reserves in their leaves during the day and remobilize them at night to provide carbon and energy for maintenance and growth. In this paper, we explore the role of a sugar-signaling metabolite, trehalose-6-phosphate (Tre6P), in regulating the accumulation and turnover of transitory starch in Arabidopsis (Arabidopsis thaliana) leaves. Ethanol-induced overexpression of trehalose-phosphate synthase during the day increased Tre6P levels up to 11-fold. There was a transient increase in the rate of starch accumulation in the middle of the day, but this was not linked to reductive activation of ADP-glucose pyrophosphorylase. A 2- to 3-fold increase in Tre6P during the night led to significant inhibition of starch degradation. Maltose and maltotriose did not accumulate, suggesting that Tre6P affects an early step in the pathway of starch degradation in the chloroplasts. Starch granules isolated from induced plants had a higher orthophosphate content than granules from noninduced control plants, consistent either with disruption of the phosphorylation-dephosphorylation cycle that is essential for efficient starch breakdown or with inhibition of starch hydrolysis by beta-amylase. Nonaqueous fractionation of leaves showed that Tre6P is predominantly located in the cytosol, with estimated in vivo Tre6P concentrations of 4 to 7 mu M in the cytosol, 0.2 to 0.5 mu M in the chloroplasts, and 0.05 mu M in the vacuole. It is proposed that Tre6P is a component in a signaling pathway that mediates the feedback regulation of starch breakdown by sucrose, potentially linking starch turnover to demand for sucrose by growing sink organs at night.