Abstract
An understanding of land plant evolution is a prerequisite for in-depth knowledge of plant biology. Here we extract and explore information hidden in the increasing number of sequenced plant genomes, from bryophytes to angiosperms, to elucidate a specific biological question – how peptide signaling evolved. To conquer land and cope with changing environmental conditions, plants have gone through transformations that must have required a revolution in cell-to-cell communication. We discuss peptides mediating endogenous and exogenous changes by interaction with receptors activating intracellular molecular signaling. Signaling peptides were discovered in angiosperms and operate in tissues and organs like flowers, seeds, vasculature, and 3D meristems that are not universally conserved across land plants. Nevertheless, orthologues of angiosperm peptides and receptors have been identified in non-flowering plants. These discoveries provoke questions regarding the co-evolution of ligands and their receptors, and whether de novo interactions in peptide signaling pathways may have contributed to generate novel traits in land plants. The answers to such questions will have profound implications for the understanding of evolution of cell-to-cell communication and the wealth of diversified terrestrial plants. Under this perspective we have generated, analyzed and reviewed phylogenetic, genomic, structural, and functional data to elucidate the evolution of peptide signaling.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
↵1 Contact information: furumizu{at}kumamoto-u.ac.jp
↵2 sawa{at}kumamoto-u.ac.jp
One sentence summary: Successful identification of orthologues of Arabidopsis signaling peptides and their receptors in non-flowering plants suggest their importance in cell-to-cell communication in all land plants.
The author(s) responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantcell.org) are: Reidunn B. Aalen (reidunn.aalen{at}ibv.uio.no) and Chihiro Furumizu (furumizu{at}kumamoto-u.ac.jp).
This is a totally rewritten version of the paper with - a new phylogenetic analyses which include receptors from the newly sequenced genomes of hornwort species and a change of algae outgroup. - a Ka/Ks comparison of LRRs and kinase domains showing that there is a stronger selection pressure against amino acid changes in the Kinase domain than in LRRs - seveeral new peptide and receptor orthologues have ben idneified and included compared to the first version of the paper.
