Root development progression involves RALF peptide-mediated ROS signaling and pectin dynamics in rice.

Area of Science:

• Plant Biology
• Molecular Biology
• Biochemistry

Background:

• Root development relies on cell division, expansion, and maturation, regulated by complex signaling networks.
• Existing knowledge lacks a unified mechanism integrating reactive oxygen species (ROS) homeostasis and cell-wall remodeling in root growth.

Purpose of the Study:

• To uncover the intrinsic regulatory hub in rice that orchestrates root development.
• To elucidate the integration of ROS transmembrane signaling and pectin structural organization.

Main Methods:

• Investigated the interaction and phosphorylation activity of THESEUS3 and RbohB.
• Analyzed the role of Rice RAPID ALKALINIZATION FACTOR4 (OsRALF4) in ROS homeostasis and pectin modification.
• Examined pectin demethylesterification and its subsequent binding with OsRALF4.

Main Results:

• Identified THESEUS3 as a receptor-like kinase that phosphorylates RbohB, promoting superoxide anion generation and negatively regulating pectin demethylesterification.
• Demonstrated that OsRALF4 acts as a ligand, balancing ROS homeostasis by inhibiting THESEUS3-RbohB signaling and modulating pectin demethylesterification.
• Showed that demethylesterified pectin binds OsRALF4, mediating pectin bundling and initiating cell expansion.

Conclusions:

• Established an integrated mechanistic framework for root development in rice.
• Highlighted the crucial role of ROS signaling and pectin organization in coordinating cell division, expansion, and maturation.