# Beyond stomatal development: SMF transcription factors as versatile toolkits for land plant evolution

## TL;DR

This paper explores how SMF genes, known for controlling stomatal development, have broader roles in plant tissue development and evolution.

## Contribution

The paper reveals that SMF genes are not only involved in stomatal development but also in other tissue types, suggesting their versatility in plant evolution.

## Key findings

- SMF genes in Marchantia polymorpha function in sporophytic setal and gametophytic epidermal tissues.
- These genes are part of gene-regulatory networks that can be co-opted for novel trait evolution.
- SMFs and related transcription factors act as general toolkits for land plant evolution.

## Abstract

As master transcription factors of stomatal development, SPEECHLESS, MUTE, and FAMA, collectively termed SMFs, are primary targets of molecular genetic analyses in the model plant Arabidopsis thaliana. Studies in other model systems identified SMF orthologs as key players in evolutionary developmental biology studies on stomata. However, recent studies on the astomatous liverwort Marchantia polymorpha revealed that the functions of these genes are not limited to the stomatal development, but extend to other types of tissues, namely sporophytic setal and gametophytic epidermal tissues. These studies provide insightful examples of gene-regulatory network co-opting, and highlight SMFs and related transcription factors as general toolkits for novel trait evolution in land plant lineages. Here, we critically review recent literature on the SMF-like gene in M. polymorpha and discuss their implications for plant evolutionary biology.