• How the biophysical properties of overlaying tissues control growth, such as the embryonic root (radicle) during seed germination, is a fundamental question. In eudicot seeds the endosperm surrounding the radicle confers coat dormancy and controls germination responses through modulation of its cell wall mechanical properties. Far less is known for grass caryopses that differ in tissue morphology. Here we report that the coleorhiza, a sheath‐like organ that surrounds the radicle in grass embryos, performs the same role in the grass weed Avena fatua (common wild oat).
• We combined innovative biomechanical techniques, tissue ablation, microscopy, tissue‐specific gene and enzyme activity expression with the analysis of hormones and oligosaccharides.
• The combined experimental work demonstrates that in grass caryopses the coleorhiza indeed controls germination for which we provide direct biomechanical evidence. We show that the coleorhiza becomes reinforced during dormancy maintenance and weakened during germination. Xyloglucan endotransglycosylases/hydrolases may have a role in coleorhiza reinforcement through cell wall remodelling to confer coat dormancy.
• The control of germination by coleorhiza‐enforced dormancy in grasses is an example of the convergent evolution of mechanical restraint by overlaying tissues.

中文翻译：

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鞘翅目种子休眠：一种控制草中发芽的新机制

• 一个基本的问题是，覆盖组织的生物物理特性如何控制生长，例如种子发芽过程中的胚根（胚根）。在双子叶植物种子中，胚根周围的胚乳赋予其休眠状态，并通过调节其细胞壁的机械特性来控制发芽反应。对于组织形态不同的草颈章鱼，人们所知甚少。在这里，我们报道了鞘翅目，鞘状器官，围绕草胚的胚根，在草杂草燕麦（普通燕麦）中起着相同的作用。
• 我们将创新的生物力学技术，组织消融，显微镜检查，组织特异性基因和酶活性表达与激素和低聚糖分析相结合。
• 组合的实验工作表明，在草冠虫中，鞘翅目确实控制了发芽，为此我们提供了直接的生物力学证据。我们表明，鞘翅目在休眠维持过程中变得增强而发芽过程中减弱。木葡聚糖内转糖基酶/水解酶可能通过细胞壁重塑赋予外套休眠而在鞘翅目菌增强中起作用。
• 草皮中通过鞘翅目增强的休眠控制发芽是通过覆盖组织逐渐收敛的机械约束的一个例子。