# The PEAPOD repressor complex in Arabidopsis stomatal development

## TL;DR

This paper explores how the PEAPOD repressor complex regulates stomatal development in Arabidopsis, focusing on its role in controlling cell division and differentiation.

## Contribution

The paper provides a review of PPD-mediated regulation of light signaling and cell cycle during stomatal development in Arabidopsis.

## Key findings

- PPD proteins form a repressor complex that halts meristemoid stem cell-like activity.
- PPD-mediated regulation influences stomatal development through light signaling and cell cycle control.

## Abstract

Stomata comprise two guard cells that function as microscopic valves in the plant epidermis, connecting mesophyll interstices to the atmosphere. Stomata regulate gas exchange and evapotranspiration, directly impacting photosynthesis and leaf temperature regulation, and their function is thus crucial for plant adaptability and fitness. In Arabidopsis, stomatal development is primarily driven by three basic helix-loop-helix transcription factors: SPEECHLESS (SPCH), MUTE, and FAMA, and occurs within the broader context of leaf development. During leaf development, a characteristic division-to-differentiation transition zone, marked by the first cell cycle arrest front (1st AF), progresses from the apex to the base of the leaf blade. The repeated division of meristemoids (M), self-renewing cells of stomatal lineages, is not halted during 1st AF, requiring a second arrest front, which is associated with activity of the PEAPOD (PPD) proteins, PEAPOD1 (PPD1) and PEAPOD2 (PPD2), which form a transcriptional repressor complex that halts M stem cell-like activity; however, the relationship between PPDs and stomatal development has not been fully elucidated. Here, we review data on PPD-mediated regulation of light signaling and the cell cycle and the influence of these factors on stomatal development.