Diethyl ether anesthesia inhibits phototropic response in <i>Arabidopsis thaliana</i> by disrupting auxin redistribution

Although the term anesthesia is mainly associated with animals, it is well known that anesthetics also affect plants through their actions on membrane properties and protein function. Here, we show that the anesthetic diethyl ether inhibits the phototropic response of Arabidopsis thaliana hypocotyls to unidirectional, low-intensity blue light. Diethyl ether acts not only on the inhibition of hypocotyl elongation but also specifically on the inhibition of phototropic signalling. This complex process consists of initial steps, defined by photoactivation of blue-light receptors, phototropins (PHOTs), and further regulators, followed by later steps involving differential accumulation of the plant growth regulator auxin on the organ’s shaded and illuminated sides, leading to heterogeneous cell elongation and bending towards light. Our data reveal that the early steps of phototropic signalling, such as PHOT1 phosphorylation, are insensitive to diethyl ether anesthesia, whereas auxin redistribution was significantly inhibited, as evidenced by the DR5:GUS assay and inhibition of auxin transporter PIN3 relocalization. This study therefore provides the first evidence about the inhibitory effect of anesthetics on auxin-mediated growth responses in plants.