Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm, 14476, Germany.
Plant Cell Environ. 2015 Jan;38(1):157-71. doi: 10.1111/pce.12381. Epub 2014 Jul 4.
Experiments were designed to compare the relationship between starch degradation and the use of carbon for maintenance and growth in Arabidopsis in source-limited and sink-limited conditions. It is known that starch degradation is regulated by the clock in source-limited plants, which degrade their starch in a linear manner such that it is almost but not completely exhausted at dawn. We asked whether this response is maintained under an extreme carbon deficit. Arabidopsis was subjected to a sudden combination of a day of low irradiance, to decrease starch at dusk, and a warm night. Starch was degraded in a linear manner through the night, even though the plants became acutely carbon starved. We conclude that starch degradation is not increased to meet demand in carbon-limited plants. This network property will allow stringent control of starch turnover in a fluctuating environment. In contrast, in sink-limited plants, which do not completely mobilize their starch during the night, starch degradation was accelerated in warm nights to meet the increased demand for maintenance and growth. Across all conditions, the rate of growth at night depends on the rate of starch degradation, whereas the rate of maintenance respiration decreases only when starch degradation is very slow.
实验旨在比较在源限制和汇限制条件下拟南芥中淀粉降解与用于维持和生长的碳利用之间的关系。已知在源限制植物中，淀粉降解受时钟调控，以线性方式降解淀粉，以至于在黎明前几乎但不完全耗尽。我们想知道在极端碳亏缺下是否会维持这种反应。拟南芥经历了一天低光照的突然组合，以在黄昏时分减少淀粉，以及温暖的夜晚。尽管植物变得严重碳饥饿，但淀粉仍在夜间以线性方式降解。我们的结论是，在碳限制植物中，淀粉降解不会增加以满足需求。这种网络特性将允许在波动的环境中严格控制淀粉周转。相比之下，在汇限制植物中，淀粉在夜间不会完全动员，因此在温暖的夜晚，淀粉降解会加速以满足维持和生长的增加需求。在所有条件下，夜间的生长速度取决于淀粉降解的速度，而只有当淀粉降解非常缓慢时，维持呼吸的速度才会下降。
