Automated analysis of three‐dimensional xylem networks using high‐resolution computed tomography

TLDR

Xylem vessel connections are key to vascular networks, yet their 3D organization has been hard to study. The study develops TANAX, a software that automatically extracts vessel dimensions and intervessel connection distributions from high‑resolution CT scans of grapevine stems. TANAX locates all vessels and intervessel connections in 4.5‑mm internode sections, analyzes their radial distribution, orientation, and shared wall area, and visualizes the reconstructed network in freely rotatable 3D renderings and virtual serial sections. Automated analysis produced comparable results to manual methods but generated orders of magnitude more data quickly, and showed that intervessel connections are more frequent laterally than dorsally or ventrally.

Abstract

• Connections between xylem vessels represent important links in the vascular network, but the complexity of three-dimensional (3D) organization has been difficult to access. • This study describes the development of a custom software package called TANAX (Tomography-derived Automated Network Analysis of Xylem) that automatically extracts vessel dimensions and the distribution of intervessel connections from high-resolution computed tomography scans of grapevine (Vitis vinifera) stems, although the method could be applied to other species. • Manual and automated analyses of vessel networks yielded similar results, with the automated method generating orders of magnitude more data in a fraction of the time. In 4.5-mm-long internode sections, all vessels and all intervessel connections among 115 vessels were located, and the connections were analyzed for their radial distribution, orientation, and predicted shared wall area. Intervessel connections were more frequent in lateral than in dorsal/ventral zones. • The TANAX-reconstructed network, in combination with commercial software, was used to visualize vessel networks in 3D. The 3D volume renderings of vessel networks were freely rotated for observation from any angle, and the 4.5 μm virtual serial sections were capable of being viewed in any plane, revealing aspects of vessel organization not possible with traditional serial sections.