Department of Plant Sciences, University of California, One Shield Avenue, Davis, CA 95616, USA; Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
Department of Plant Sciences, University of California, One Shield Avenue, Davis, CA 95616, USA.
J Plant Physiol. 2019 Mar-Apr;234-235:80-93. doi: 10.1016/j.jplph.2019.01.007. Epub 2019 Jan 14.
Starch is a significant store of sugars, and the starch-sugar interconversion in source and sink tissues plays a profound physiological role in all plants. In this review, we discuss how changes in starch metabolism can facilitate adaptive changes in source-sink carbon allocation for protection against environmental stresses. The stress-related roles of starch are described, and published mechanisms by which starch metabolism responds to short- or long-term water deficit, salinity, or extreme temperatures are discussed. Numerous examples of starch metabolism as a stress response are also provided, focusing on studies where carbohydrates and cognate enzymes were assayed in source, sink, or both. We develop a model that integrates these findings with the theoretical and known roles of sugars and starch in various species, tissues, and developmental stages. In this model, localized starch degradation into sugars is vital to the plant cold stress response, with the sugars produced providing osmoprotection. In contrast, high starch accumulation is prominent under salinity stress, and is associated with higher assimilate allocation from source to sink. Our model explains how starch-sugar interconversion can be a convergent point for regulating carbon use in stress tolerance at the whole-plant level.
淀粉是糖分的重要储存库，源库组织中的淀粉-糖相互转化在所有植物中都具有深远的生理作用。在这篇综述中，我们讨论了淀粉代谢的变化如何促进源库碳分配的适应性变化，以抵御环境胁迫。描述了与胁迫相关的淀粉作用，并讨论了淀粉代谢对短期或长期水分亏缺、盐度或极端温度的响应机制。还提供了许多淀粉代谢作为应激反应的例子，重点关注在源、汇或两者中测定碳水化合物和相关酶的研究。我们提出了一个模型，将这些发现与各种物种、组织和发育阶段中糖和淀粉的理论和已知作用整合在一起。在该模型中，局部淀粉降解为糖对于植物的冷胁迫反应至关重要，所产生的糖提供渗透保护。相比之下，在盐胁迫下，淀粉的大量积累较为明显，并且与源到汇的更多同化产物分配有关。我们的模型解释了淀粉-糖相互转化如何成为在整个植物水平上调节胁迫耐受性中碳利用的趋同点。
