Non-invasive and continuous recordings of auxin fluxes in intact root apex with a carbon-nanotube-modified and self-referencing microelectrode.

Auxin (also known as indole-3-acetic acid, IAA) represents an ancient signaling molecule of plants that also exerts bioactive actions on yeast and animal cells. Importantly, IAA emerges as a new anticancer agent due to the ability of oxidatively activated IAA to selectively kill tumor cells. IAA acts as a pheromone-like molecule in brown algae, whereas the hormone concept of IAA domi- nates current plant biology. However, recent advances also favor the morphogen- and transmitter-like nature of IAA in plants, mak- ing this small molecule one of the most unique molecules in the eukaryotic superkingdom. Here, we introduce new technology for the continuous measuring of IAA Xuxes in living cells, tissues, and whole organs that is based on a carbon nanotube-modiWed and self- referencing microelectrode speciWc for IAA. This technique not only will advance our knowledge of how IAA regulates plant devel- opment but will also be applicable in medicine for its potential use in cancer therapy.