Biophysical Perspectives of Xylem Evolution: is there a Tradeoff of Hydraulic Efficiency for Vulnerability to Dysfunction?

TLDR

Water transport in land plants occurs under negative pressure, making water metastable; vessels are prone to cavitation when gas-filled voids appear, filling with air and halting transport until bubbles dissolve, and recent insights into cavitation and bubble dissolution deepen our understanding of these processes. The review examines the evolution of xylem structure within the framework of plant water transport biophysics. It synthesizes current biophysical knowledge to interpret how structural changes influence hydraulic function. This synthesis yields a clearer understanding of the relationship between xylem structure and function.

Abstract

In this review, we discuss the evolution of xylem structure in the context of our current understanding of the biophysics of water transport in plants. Water transport in land plants occurs while water is under negative pressure and is thus in a metastable state. Vessels filled with metastable water are prone to dysfunction by cavitation whenever gas-filled voids appear in the vessel lumen. Cavitated vessels fill with air and are incapable of water transport until air bubbles dissolve. We know much more about how cavitations occur and the conditions under which air bubbles (embolisms) dissolve. This gives us an improved understanding of the relations hip between xylem structure and function.