Abstract
Diverse branching forms have evolved multiple times across the tree of life to facilitate resource acquisition and exchange with the environment. In the vascular plant group, the ancestral pattern of branching involves dichotomy of a parent shoot apex to form two new daughter apices. The molecular basis of axillary branching in Arabidopsis is well understood, but few regulators of dichotomous branching are known. Through analyses of dichotomous branching in the lycophyte, Selaginella kraussiana, we identify PIN-mediated auxin transport as an ancestral branch regulator of vascular plants. We show that short-range auxin transport out of the apices promotes dichotomy and that branch dominance is globally coordinated by long-range auxin transport. Uniquely in Selaginella, angle meristems initiate at each dichotomy, and these can develop into rhizophores or branching angle shoots. We show that long-range auxin transport and a transitory drop in PIN expression are involved in angle shoot development. We conclude that PIN-mediated auxin transport is an ancestral mechanism for vascular plant branching that was independently recruited into Selaginella angle shoot development and seed plant axillary branching during evolution.
| Original language | English |
|---|---|
| Article number | dev201209 |
| Journal | Development |
| Volume | 150 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 15 Mar 2023 |
Bibliographical note
Funding Information:We thank the Leverhulme Trust (RPG-2018-220) and the Gatsby Charitable Foundation for funding our work. Open access funding provided by the University of Bristol. Deposited in PMC for immediate release.
Funding Information:
We thank Jane Langdale and Julie Bull for providing plant tissue, and Jane Langdale, Tom Hughes, Chris Whitewoods and the Sainsbury Laboratory for use of histology facilities. We thank the authors of Ge et al. (2016) for sharing their data, and Alex Paterson and Ben White for assistance with bioinformatic analyses. We thank the Wolfson Bioimaging Facility for their support and assistance with Electron Microscopy and members of the Harrison Lab for comments on a manuscript draft. We thank the Leverhulme Trust (RPG-2018-220) and the Gatsby Charitable Foundation for funding our work. Open access funding provided by the University of Bristol. Deposited in PMC for immediate release.
Publisher Copyright:
© 2023. Published by The Company of Biologists Ltd.