Imaging the three-dimensional structure of haustoria in host and Cuscuta interactions via laser ablation tomography

Cuscuta spp. are stem holoparasitic plants that use haustoria to draw water, photosynthates, and nutrients from host plant vascular systems. Cuscuta has served as a model plant for understanding plant-plant interactions and haustoria development of stem parasitic plants; however, studies of the three-dimensional (3D) internal host-parasite interface and interconnections are limited due to their unique structures developed inside host stems. This study investigates laser ablation tomography (LATscan) technology, which generates 3D reconstructions from stacked high-resolution 2D cross-sectional images. LATscan imaging of Cuscuta invading Arabidopsis (Arabidopsis thaliana) and beet (Beta vulgaris) stems yielded 3D renderings and detailed images of the anatomy of Cuscuta-host tissue interactions, including Cuscuta searching hyphae penetrating the host vasculature. Laser-tissue interactions generated color contrast and facilitated easy differentiation between Cuscuta and host tissues in 3D renderings and 2D images, demonstrating that LATscan technology can be an efficient tool to investigate the development and function of host-parasitic plant interactions.