Petre Ivanov Dobrev

Introduction During the transition from water to land, plants underwent a series of developmental innovations, leading to the establishment of a complex body (Harrison, 2017; Donoghue et al., 2021; Bowman, 2022). A key regulator of land plant development is the phytohormone auxin, which acts through local biosynthesis and directional transport, resulting in the formation of concentration gradients (Friml, 2022).

Abstract The role of auxin indole-3-acetic acid (IAA), a phytohormone with numerous morphogenic functions, is now well-established in land plants. Although the role of IAA and its transport in algae remains unclear, PIN-driven auxin export is probably an ancient and conserved trait within Streptophytes. Among streptophyte algae, Chara represents a genus with a considerable degree of complexity in body arrangement.

Introduction Cell growth is a fundamental part of plant development and responses to external stimuli. The combination of cell division and cell elongation is the dominant factor in plant body formation. In the root tip, cells divide in the meristematic zone (Dolan et al., 1993) and then elongate in the elongation zone, driving the root growth (Beemster & Baskin, 1998).