Evidence for Early Evolution of Sulfated Peptide Signaling in Plant Development

Area of Science:

• Plant Biology
• Developmental Biology
• Molecular Plant Science

Background:

• Plant development relies on cell proliferation and expansion for tissue and organ formation.
• Cell-to-cell communication coordinating expansion is crucial but not fully understood.
• Sulfotyrosyl peptide signaling modulates organ growth in seed plants.

Purpose of the Study:

• Investigate the role of TYROSYL PROTEIN SULFOTRANSFERASE (TPST) in non-vascular plant development.
• Determine the necessity of TPST activity for cell expansion and organ formation in *Physcomitrium patens*.
• Explore the conservation and function of sulfated peptide signaling in plants.

Main Methods:

• Generated a null mutant (Δtpst) in *Physcomitrium patens* to study TPST function.
• Performed mutational analysis of *P. patens* TPST to identify key functional residues.
• Assessed the rescue of developmental deficits by applying sulfated signaling peptides (PSY1) from different plant species.

Main Results:

• The *Δtpst* mutant exhibited reduced size and failed to fully expand gametophores.
• Histidine 124 in *P. patens* TPST was identified as essential for its catalytic function.
• Application of PSY1 peptides from *P. patens* and *Arabidopsis thaliana* rescued all developmental defects in the *Δtpst* mutant.

Conclusions:

• TPST is essential for cell expansion and development in the non-vascular plant *Physcomitrium patens*.
• TPST activity is necessary for the sulfation of PSY peptides, a critical step in plant growth.
• PSY signaling is evolutionarily conserved and plays a vital role in plant development across diverse species.