Agostinelli Daniele, DeSimone Antonio, Noselli Giovanni
SISSA-International School for Advanced Studies, Trieste, Italy.
The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy.
Front Plant Sci. 2021 Mar 23;12:608005. doi: 10.3389/fpls.2021.608005. eCollection 2021.
We present a three-dimensional morphoelastic rod model capable to describe the morphogenesis of growing plant shoots driven by differential growth. We discuss the evolution laws for endogenous oscillators, straightening mechanisms, and reorientations to directional cues, such as gravitropic reactions governed by the avalanche dynamics of statoliths. We use this model to investigate the role of elastic deflections due to gravity loading in circumnutating plant shoots. We show that, in the absence of endogenous cues, pendular and circular oscillations arise as a critical length is attained, thus suggesting the occurrence of an instability triggered by exogenous factors. When also oscillations due to endogenous cues are present, their weight relative to those associated with the instability varies in time as the shoot length and other biomechanical properties change. Thanks to the simultaneous occurrence of these two oscillatory mechanisms, we are able to reproduce a variety of complex behaviors, including trochoid-like patterns, which evolve into circular orbits as the shoot length increases, and the amplitude of the exogenous oscillations becomes dominant.
我们提出了一种三维形态弹性杆模型，该模型能够描述由差异生长驱动的植物嫩枝生长的形态发生过程。我们讨论了内源性振荡器的演化规律、伸直机制以及对方向线索的重新定向，例如由平衡石的雪崩动力学控制的向重力反应。我们使用这个模型来研究重力加载引起的弹性挠度在植物嫩枝回旋转头中的作用。我们表明，在没有内源性线索的情况下，当达到临界长度时会出现摆动和圆周振荡，这表明由外源性因素引发了一种不稳定性。当也存在由内源性线索引起的振荡时，随着嫩枝长度和其他生物力学特性的变化，它们相对于与不稳定性相关的振荡的权重会随时间变化。由于这两种振荡机制同时出现，我们能够再现各种复杂行为，包括类似摆线的模式，随着嫩枝长度增加，这些模式会演变成圆形轨道，并且外源性振荡的幅度变得占主导地位。
