Gazing at Cell Wall Expansion under a Golden Light.

In plants, cell growth is constrained by a stiff cell wall, at least this is the way textbooks usually present it. Accordingly, many studies have focused on the elasticity and plasticity of the cell wall as prerequisites for expansion during growth. With their specific evolutionary history, cell wall composition, and environment, brown algae present a unique configuration offering a new perspective on the involvement of the cell wall, viewed as an inert material yet with intrinsic mechanical properties, in growth. In light of recent findings, we explore here how much of the functional relationship between cell wall chemistry and intrinsic mechanics on the one hand, and growth on the other hand, has been uncovered in brown algae. Highlights There is a current overwhelming paradigm of cell growth that promotes one main scenario: the intrinsic elasticity or plasticity of the cell wall controls growth. In brown algae, which evolved independently from land plants and fungi, both the structure and chemical composition of the cell wall differ from their counterparts (i.e., cell wall of land plants, fungi, oomycetes, and other algae). Beyond a complete inventory of cell wall components, their proportion and potential chemical modifications and interactions (covalent and/or electrostatic) with each other are still largely unknown, even in the most studied organisms, such as land plants. Data on land plants and brown algae show that the propensity of the cell wall to grow does not systematically depend on its intrinsic mechanical properties. Complexity and diversity of cell wall compositions and structures make preconceived transposition of cell wall growth mechanisms hazardous. [ABSTRACT FROM AUTHOR]