How do Syntrichia mosses carry water when they’ve nothing to carry it in?

A team led by Jauregui-Lazo has recently delved into the complex relationship between morphology and functionality in mosses. Unlike vascular plants, mosses do not have any internal tubes to carry water around their body nor roots to pick it up. Jauregui-Lazo and colleagues have published a study in AoB PLANTS investigating the water conduction and storage capabilities of a moss genus, Syntrichia. This research gives us insight into how these plants have adapted to diverse environments by examining how they absorb, transport, and retain water — a vital aspect of survival for a group of plants often found in challenging habitats.

The researchers revealed fascinating details about the water relationships in Syntrichia, a moss that can externally transport and store water via a process known as ectohydry. Using advanced microscopy techniques and experimental approaches, they discovered that individual species have unique morphological traits that contribute to their respective water conduction and storage capabilities. In the 11 Syntrichia species studied, the scientists found significant variations in water holding capacity, the speed of water conduction, and hydration levels. The implications of these findings are profound, opening up a window into understanding the evolutionary and ecological trade-offs these mosses face.

Syntrichia mosses’ relationship with water is intricately linked to their distinct ecological niches. Their ability to conduct water from the base of the stem to the leaves allows them to thrive in challenging environments. This process is made possible by the abundance of capillary spaces within the plants, which serve as the “highways” for water transportation. However, the functioning of these capillaries is not straightforward. A complex interplay of factors, including cell anatomy, the architecture of the stem, and the overall density of moss clusters, dramatically influences their effectiveness in conducting water.

To gain a comprehensive understanding of this process, Jauregui-Lazo and colleagues conducted meticulous microscopic studies and developed experimental models for observing the leaves of the Syntrichia species. They also measured hydration/dehydration curves to understand the rate of water conduction and dehydration in the moss. Through this approach, they could discern the unique roles of different morphological features in the mosses’ water conduction and storage process.

Jauregui-Lazo and colleagues conclude their article by saying:

Ectohydry is a complex phenomenon where multiple factors of morphology play a role in space and time. In a recent survey, Patiño et al. (2022) highlighted that the function of morphological features, such as hairpoints, paraphyllia and paraphyses, in relation to fitness and physiological performance remains open as one of 50 fundamental questions in bryology. Here, we suggest a conceptual model to analyse the external water relationships of mosses in an integrated manner (Fig. 6). Future studies are needed to survey traits relating to external water conduction more widely among mosses. In addition, the evolution of environmental preferences needs to be studied in more detail. Once this additional information is available, phylogenetic comparative methods should be applied to determine the evolutionary origins of structural traits in relation to the environment present at that time. In this way, truly adaptive changes in evolution can be discovered.

Jauregui-Lazo et al. 2023

READ THE ARTICLE
Jauregui-Lazo, J., Wilson, M. and Mishler, B.D. (2023) “The dynamics of external water conduction in the dryland moss Syntrichia,” AoB PLANTS, 15(3), p. lad025. Available at: https://doi.org/10.1093/aobpla/plad025.