Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany.
Institute of Experimental Physics 5, University of Würzburg, Am Hubland, 97074, Würzburg, Germany.
New Phytol. 2017 Dec;216(4):1181-1190. doi: 10.1111/nph.14736. Epub 2017 Aug 11.
Germination, the process whereby a dry, quiescent seed springs to life, has been a focus of plant biologist for many years, yet the early events following water uptake, during which metabolism of the embryo is restarted, remain enigmatic. Here, the nature of the cues required for this restarting in oilseed rape (Brassica napus) seed has been investigated. A holistic in vivo approach was designed to display the link between the entry and allocation of water, metabolic events and structural changes occurring during germination. For this, we combined functional magnetic resonance imaging with Fourier transform infrared microscopy, fluorescence-based respiration mapping, computer-aided seed modeling and biochemical tools. We uncovered an endospermal lipid gap, which channels water to the radicle tip, from whence it is distributed via embryonic vasculature toward cotyledon tissues. The resumption of respiration is initiated first in the endosperm, only later spreading to the embryo. Sugar metabolism and lipid utilization are linked to the spatiotemporal sequence of tissue rehydration. Together, this imaging study provides insights into the spatial aspects of key events in oilseed rape seeds leading to germination. It demonstrates how seed architecture predetermines the pattern of water intake, which sets the stage for the orchestrated restart of life.
发芽是一个干燥、静止的种子恢复生机的过程，多年来一直是植物生物学家关注的焦点，但在吸水后，即胚胎代谢重新开始的早期事件仍然是个谜。在这里，研究了油菜（甘蓝型油菜）种子中重新开始所需的线索的性质。设计了一种整体的体内方法来显示在发芽过程中发生的水的进入和分配、代谢事件和结构变化之间的联系。为此，我们结合了功能磁共振成像与傅里叶变换红外显微镜、基于荧光的呼吸映射、计算机辅助种子建模和生化工具。我们发现了一个胚乳脂质间隙，它将水引导到胚根尖端，然后通过胚胎血管系统分配到子叶组织。呼吸的恢复首先在胚乳中开始，然后才扩散到胚胎中。糖代谢和脂质利用与组织再水合的时空顺序有关。总的来说，这项成像研究提供了对导致油菜种子发芽的关键事件的空间方面的深入了解。它展示了种子结构如何预先确定水分摄入的模式，为生命的协调重新启动奠定了基础。
