PubMed · 2026-07-02
A chemical signaling system that plants use to coordinate cell growth was already present in mosses, ancient plants that lack roots or leaves. This shows the system predates the evolution of vascular plants by hundreds of millions of years, and the signal peptide is so conserved that a moss version rescues broken Arabidopsis plants and vice versa.
Moss plants (Physcomitrium patens) lacking the TPST enzyme were smaller, formed fewer filaments, and completely failed to develop leafy shoot structures called gametophores, proving TPST is essential even in non-vascular plants.
Histidine 124 was identified as the critical catalytic residue in TPST; mutating it abolished enzyme function.
PSY1 peptide from either Arabidopsis or P. patens fully rescued all developmental defects in TPST-null moss, and moss PSY1 promotes root elongation in both Arabidopsis and rice, demonstrating functional conservation across an estimated 500 million years of plant evolution.
