Plants are subjected to multiple abiotic and biotic environmental stresses from which, contrarily to animals, they cannot escape. To survive, they developed sophisticated defense strategies during evolution. When plants perceive stress they can adjust their growth and development. Mechanical stress, for instance, can be caused to plants by strong winds, rain, and physical contact. In response to thigmo (touch) stresses, plants undergo various morphological and physiological changes including dwarf growth, thicker stems and delay in flowering. Thigmomorphogenesis (morphology change due to touch) was described for long time but although progress has been made in mechanobiology, specific sensors and signalling pathways explaining the physiological basis of mechanical stress are still unknown.
Gibberellins (GAs) are phytohormones that control plant growth and development. Recently, we showed that GA-signalling regulates thigmomorphogenesis in Arabidopsis. We provided evidence that decreasing GA-levels by GA-catabolism, via transcriptional control of AtGA2ox7, regulates growth inhibition and delay in flowering upon mechano-stimulation. Without AtGA2ox7 the plant does not react on touching (see below). One of our research topics is to unravel touch signalling pathways.