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ABSTRACT A fascinating feature of land plants is their ability to continually initiate new tissues and organs throughout their lifespan, driven by a pool of pluripotent stem cells located in meristems. In seed plants, various types of meristems are initiated and maintained during the sporophyte generation, while their gametophytes lack meristems and rely on sporophyte tissues for growth. In contrast, seed‐free vascular plants, such as ferns, develop meristems during both the sporophyte and gametophyte generations, allowing for the independent growth of both generations. Recent findings have highlighted both conserved and lineage‐specific roles of the HAIRY MERISTEM (HAM) family of GRAS‐domain transcriptional regulators in various meristems throughout the land plant lifecycle. Here, we review and discuss howHAMgenes maintain meristem indeterminacy in both sporophytes and gametophytes, with a focus on studies performed in two model species: the flowering plantArabidopsis thalianaand the fernCeratopteris richardii. Additionally, we summarize the crucial and tightly regulated functions of the microRNA171 (miR171)‐HAM regulatory modules, which define HAM spatial patterns and activities during meristem development across various meristem identities in land plants.
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Illuminating the role of the calyptra in sporophyte development
The study of moss calyptra form and function began almost 250 years ago, but calyptra research has remained a niche endeavor focusing on only a small number of species. Recent advances have focused on calyptra cuticular waxes, which function in dehydration protection of the immature sporophyte apex. The physical presence of the calyptra also plays a role in sporophyte development, potentially via its influence on auxin transport. Progress developing genomic resources for mosses beyond the model Physcomitrium patens, specifically for species with larger calyptrae and taller sporophytes, in combination with advances in CRISPR-Cas9 genome editing will enable the influence of the calyptra on gene expression and the production of RNAs and proteins that coordinate sporophyte development to be explored.
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- Award ID(s):
- 2046467
- PAR ID:
- 10569948
- Publisher / Repository:
- ScienceDirect
- Date Published:
- Journal Name:
- Current Opinion in Plant Biology
- Volume:
- 81
- ISSN:
- 1369-5266
- Page Range / eLocation ID:
- 102565
- Subject(s) / Keyword(s):
- Auxin Bryophytes Cuticle chemistry Funaria hygrometrica Gametophyte Model systems Mosses Physcomitrium patens Reproductive biology
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.pbi.2024.102565
