Can Plants Move Like Animals? A Three-Dimensional Stereovision Analysis of Movement in Plants

Abstract

In this article we adapt a methodology customarily used to investigate movement in animals to study the movement of plants. The targeted movement is circumnutation, a helical organ movement widespread among plants. It is variable due to a different magnitude of the trajectory (amplitude) exhibited by the organ tip, duration of one cycle (period), circular, elliptical, pendulum-like or irregular shape and the clockwise and counterclockwise direction of rotation. The acquisition setup consists of two cameras used to obtain a stereoscopic vision for each plant. Cameras switch to infrared recording mode for low light level conditions, allowing continuous motion acquisition during the night. A dedicated software enables semi-automatic tracking of key points of the plant and reconstructs the 3D trajectory of each point along the whole movement. Three-dimensional trajectories for different points undergo a specific processing to compute those features suitable to describe circumnutation (e.g., maximum speed, circumnutation center, circumnutation length, etc.). By applying our method to the approach-to-grasp movement exhibited by climbing plants (Pisum sativum L.) it appears clear that the plants scale movement kinematics according to the features of the support in ways that are adaptive, flexible, anticipatory and goal-directed, reminiscent of how animals would act.

Evidence of motor intentions in plants: A kinematical study.

“…The dependent variables specifically tailored to test our experimental hypothesis on the basis of previous kinematical studies on approach-to-grasp in pea plants (e.g., Simonetti et al, 2021) and motor intentions in humans (Georgiou et al, 2007; Becchio et al, 2008a) were: (a) the spatial trajectories designed by the tip of the tendril (Figure 1C); (b) the duration of the total number of circumnutations by the tendril. This time was calculated from the time the plantula was planted and the time the tendril grasped the support; (c) the maximum velocity of the tendril; (d) the percentage of time at which the maximum tendril velocity was reached during circumnutation ; (e) the mean duration of the circumnutations , (f) the distance of the center of the circumnutation from the stimulus.…”

Classifying Circumnutation in Pea Plants via Supervised Machine Learning

“…Nutation kinematics of different organs has served to lay a foundation of several mechanisms postulated as responsible for the movement in question with tendrils being amongst the most investigated [ 3 , 20 , 21 , 22 ]. Tendrils serve climbing plants by providing a parasitic alternative to building independently stable structural supports, allowing the plant to wend its way to sunlight and numerous ecological niches [ 23 ].…”

Ascent and attachment in pea plants: a matter of iteration

“…An ad hoc software (Ab. Acus s.r.l., Milan, Italy) developed by Matlab was used to position the markers and track their position frame-by-frame on the images acquired by the two cameras to reconstruct the 3D trajectory of each marker 41 . All leaves developed by the plants were analyzed from the germination of the seed until the plant collapsed (i.e., 'No Support' condition; Fig.…”