Organisms have a variety of three-dimensional (3D) structures that change over time. These changes include twisting, which is 3D deformation that cannot happen in two dimensions. Twisting is linked to important adaptive functions of organs, such as adjusting the orientation of leaves and flowers in plants to align with environmental stimuli (e.g. light, gravity). Despite its importance, the underlying mechanism for twisting remains to be determined, partly because there is no rigorous method for quantifying the twisting of plant organs. Conventional studies have relied on approximate measurements of the twisting angle in 2D, with arbitrary choices of observation angle. Here, we present the first rigorous quantification of the 3D twisting angles of Arabidopsis petioles based on light sheet microscopy. Mathematical separation of bending and twisting with strict definition of petiole cross-sections were implemented; differences in the spatial distribution of bending and twisting were detected via the quantification of angles along the petiole. Based on the measured values, we discuss that minute degrees of differential growth can result in pronounced twisting in petioles.

生物体具有多种随时间变化的三维 (3D) 结构。这些变化包括扭曲，这是在二维中无法发生的 3D 变形。扭曲与器官的重要适应功能有关，例如调整植物叶子和花朵的方向以适应环境刺激（例如光、重力）。尽管它很重要，但扭曲的潜在机制仍有待确定，部分原因是没有严格的方法来量化植物器官的扭曲。传统的研究依赖于二维扭转角度的近似测量，并且任意选​​择观察角度。在这里，我们首次基于光片显微镜对拟南芥叶柄的 3D 扭转角度进行严格量化。实现了弯曲和扭曲的数学分离，并严格定义了叶柄横截面；通过量化沿着叶柄的角度来检测弯曲和扭曲的空间分布的差异。根据测量值，我们讨论微小程度的差异生长可能导致叶柄明显扭曲。