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

Premise: Most studies of the movement of orchid fruits and roots during plantdevelopment have focused on morphological observations; however, further geneticanalysis is required to understand the molecular mechanisms underlying thisphenomenon. A precise tool is required to observe these movements and harvesttissue at the correct position and time for transcriptomics research.Methods: We utilized three‐dimensional (3D) micro–computed tomography (CT)scans to capture the movement of fast‐growing Erycina pusilla roots, and built anintegrated bioinformatics pipeline to process 3D images into 3D time‐lapse videos. Torecord the movement of slowly developing E. pusilla and Phalaenopsis equestris fruits,two‐dimensional (2D) photographs were used.Results: The E. pusilla roots twisted and resupinated multiple times from earlydevelopment. The first period occurred in the early developmental stage (77–84 daysafter germination [DAG]) and the subsequent period occurred later in development(140–154 DAG). While E. pusilla fruits twisted 45° from 56–63 days after pollination(DAP), the fruits of P. equestris only began to resupinate a week before dehiscence(133 DAP) and ended a week after dehiscence (161 DAP).Discussion: Our methods revealed that each orchid root and fruit had anindependent direction and degree of torsion from the initial to the final position.Our innovative approaches produced detailed spatial and temporal information onthe resupination of roots and fruits during orchid development.