Three-dimensional quantification of twisting in the Arabidopsis petiole

Abstract

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.

Multiscale microscopy to decipher plant cell structure and dynamics

“…(2018) imaged fluorescently tagged phospholipase Dα1 in Arabidopsis using LSM and revealed a developmental‐specific expression pattern. Otsuka & Tsukaya (2021) quantitatively analyzed 3D distortion angles in Arabidopsis petioles with LSM. Valuchova et al .…”

Orchid fruit and root movement analyzed using 2D photographs and a bioinformatics pipeline for processing sequential 3D scans

“…Most plants grow linearly or circumferentially (Steeves and Sussex, 1989), but others grow in non-linear directions, such as in twists and spirals, known as helical growth. Here, twisting is defined as a cross-sectional rotation around a plant's midline (Otsuka and Tsukaya, 2021). Several terms, each with a slightly different denotation, have been applied to stimulus-induced twisting, including tropism (Snow, 1962), heliotropism (Atamian et al, 2016), torsion (Borchers et al, 2018), circumnutation (Fiorello et al, 2020), and resupination (Dines and Bell, 1994;Harley et al, 2017).…”