# Modelling stomatal mechanics: a critical review

## TL;DR

This paper reviews the history and current state of understanding stomatal mechanics, highlighting gaps in knowledge and suggesting ways to improve models of how stomata function.

## Contribution

The paper introduces a framework to critically assess stomatal biomechanics models and identifies key areas needing further empirical investigation.

## Key findings

- Current models of stomatal mechanics lack a complete and coherent understanding of the process.
- Empirical data on cell shape changes during stomatal response is limited and needs further investigation.
- Reinterpreting existing data could lead to new insights into stomatal function.

## Abstract

The biomechanics of stomatal movements have fascinated scientists for almost 150 yr, yet we still lack a conclusive and coherent mechanistic understanding of the process. In this review, we present a framework that allows critical insight into the state of knowledge of stomatal biomechanics, with a focus on modelling approaches. We apply the framework in two ways. First, contextualising the history, we show how the nature and function of models of stomatal mechanics have evolved. Second, we use the framework to appraise three key features of extant models: cell wall mechanical properties, guard cell shape, and the role of surrounding epidermal cells. We evaluate the empirical origin and model representations of these features, summarising how each is currently thought to explain stomatal function, while also identifying limitations in our understanding. We propose that a better appreciation of gaps in knowledge in the empirical domain, particularly the actual shifts in cell shape during stomatal response, combined with careful reinterpretation of existing data, will lead to new insight and a more complete understanding of stomatal mechanics.