Water Movement in Vascular Plants: A Primer

TL;DR

This paper reviews the complex mechanisms of water transport in vascular plants, emphasizing the cohesion-tension theory and recent multidisciplinary research that advances understanding of sap ascent and vascular stress management.

Contribution

It provides a comprehensive review of recent literature, integrating multiple disciplines to deepen understanding of water transport mechanisms in vascular plants.

Findings

Cohesion-tension theory is largely supported by recent evidence.

Vascular stress management in plants involves complex, not fully understood mechanisms.

Multidisciplinary approaches have enriched understanding of plant water transport.

Abstract

The origin of land plants was one of the most important events in evolutionary history of earth in terms of its broad impact on metazoan life and the biotic environment. Because vascular tissues enabled land plants to meet the challenges of terrestrial life, it is important to understand the mechanistic basis of water transport through these tissues from soil to the canopy of trees, in some cases almost 100 meters high. The answers to these questions involve not only the biology of plant vasculature, but also the physical properties of water that enable such transport. Although early researchers proposed the hypothesis of cohesion-tension of water as the likely mechanism for sap ascent, the exact mechanism of transport continues to be a hotly debated topic in the field of plant physiology. This debate continues to be enriched with several sophisticated studies on plants of various morphologies growing in diverse habitats. Although a wealth of evidence has upheld the cohesion-tension theory as being fundamentally correct, several important details about how plants deal with vascular stress remain unknown. Here, we review the recent literature on this topic with the aim of highlighting how a multi-disciplinary perspective has contributed to our understanding of the cohesion-tension theory of sap ascent in plants.