Distinct and redundant roles of the Arabidopsis OCTOPUS gene family in plant growth beyond phloem development.

The Arabidopsis root apical meristem is an excellent model for studying plant organ growth that involves a coordinated process of cell division, elongation, and differentiation, while each tissue type develops on its own schedule. Among these tissues, the protophloem is particularly important, differentiating early to supply nutrients and signalling molecules to the growing root tip. The OCTOPUS (OPS) protein and its homolog OPS-LIKE 2 (OPL2) are essential for proper root protophloem differentiation and, likely through this role, indirectly promote root growth.

OCTOPUS-LIKE 2, a novel player in Arabidopsis root and vascular development, reveals a key role for OCTOPUS family genes in root metaphloem sieve tube differentiation.

Protophloem and metaphloem sieve tubes are essential for transporting carbohydrates and signalling molecules towards sink tissues. OCTOPUS (OPS) was previously identified as an important regulator of protophloem differentiation in Arabidopsis roots. Here, we investigated the role of OCTOPUS-LIKE 2 (OPL2), a gene homologous to OPS.