Epigenetic regulation in the shoot apical meristem

https://doi.org/10.1016/j.pbi.2022.102267Get rights and content
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Highlights

  • As progenitors of the gametes, SAM stem cells are crucial for understanding epigenetic inheritance and epigenome resetting.

  • Regulation of stem cell promoting transcription factors is complex, involving multiple layers of chromatin modifications.

  • SAM stem cells need to protect their genome and epigenome while at the same time maintaining developmental flexibility.

  • SAM stem cells likely harbor specific chromatin states and transposon defense systems.

Abstract

Epigenetic mechanisms form the basis of cellular memory, developmental decisions, and the cellular immune system that defends against transposons and viruses. Organs develop from the shoot apical meristem (SAM) to shape the plant's areal phenotype, and stem cells in the SAM serve as a functional germline. While many details on the regulation of stem cell pool size, organ initiation, and patterning at the meristem periphery are known, we know surprisingly little about the molecular characteristics of SAM cells, including their epigenome and how it changes during development. Here, we summarize information on epigenetic regulation of selected genes necessary for stem cell maintenance. As recent evidence suggests that SAM stem cells might be a hotspot of transposon activation, we discuss this aspect of epigenetic control in the meristem and speculate on mechanisms that maintain the flexibility of SAM stem cells in response to developmental or environmental cues.

Keywords

Shoot apical meristem
SAM
Stem cells
WUSCHEL (WUS)
CLAVATA3 (CLV3)
L2 layer
AGAMOUS (AG)
Plant virus
LTR/Gypsy
Transposon
Chromatin
DNA methylation
Small RNAs (sRNAs)
Histone PTMs (H3K27me3, H3K4me3)

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