Search for: All records

Summary Plants show a rapid systemic response to a wide range of environmental stresses, where the signals from the site of stimulus perception are transmitted to distal organs to elicit plant‐wide responses. A wide range of signaling molecules are trafficked through the plant, but a trio of potentially interacting messengers, reactive oxygen species (ROS), Ca²⁺and electrical signaling (‘trio signaling’) appear to form a network supporting rapid signal transmission. The molecular components underlying this rapid communication are beginning to be identified, such as theROSproducingNAPDHoxidaseRBOHD, the ion channel two pore channel 1 (TPC1), and glutamate receptor‐like channelsGLR3.3 andGLR3.6. The plant cell wall presents a plant‐specific route for possible propagation of signals from cell to cell. However, the degree to which the cell wall limits information exchange between cells via transfer of small molecules through an extracellular route, or whether it provides an environment to facilitate transmission of regulators such asROSor H⁺remains to be determined. Similarly, the role of plasmodesmata as both conduits and gatekeepers for the propagation of rapid cell‐to‐cell signaling remains a key open question. Regardless of how signals move from cell to cell, they help prepare distant parts of the plant for impending challenges from specific biotic or abiotic stresses. 

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.