Revisiting the growth rate hypothesis: Towards a holistic stoichiometric understanding of growth

Isanta‐Navarro, Jana; Prater, Clay; Peoples, Logan M.; Loladze, Irakli; Phan, Tin; Jeyasingh, Punidan D.; Church, Matthew J.; Kuang, Yang; Elser, James J.

doi:10.1111/ele.14096

Pollen tubes and root hairs grow by a highly focused deposition of new wall and membrane materials at their growing apex. Comparison of the machinery that localises such growth between these cell types has revealed common components, providing important insight into how plant cells control cell expansion. Such elements include the small GTPases (e.g. ROPs and RABs), gradients and intricate spatial patterning in the fluxes of ions (e.g. Ca2+ and H+) and partitioning of membrane lipids (such as the phosphoinositides). These regulators are coupled to focused action of the secretory machinery (e.g. the exocyst) and cytoskeletal dynamics, with integral roles emerging for actin, tubulin and their associated motor proteins. These components form an integrated regulatory network that imposes robust spatial localisation of the growth machinery and so supports the production of an elongating tube-like growth form where cell expansion is limited to the very apex, that is, tip growth.

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