Kanamycin reveals the role played by glutamate receptors in shaping plant resource allocation.

Ionotropic glutamate receptors (iGluRs) play important roles in neurotransmission in animals. There is growing evidence that iGluRs also play important roles in plants. Using a chemical genetics approach, which combined a pH-homeostasis mutant of Arabidopsis thaliana (de-etiolated3), several different iGluR agonists, molecular modelling, and reporter gene expression in transgenic plants, we provide evidence that iGluR agonism can induce dramatic changes in plant development and metabolism. Systematic hypothesis testing revealed a signalling circuit that integrates amino acid and sugar signals to affect elongation growth and the deposition of carbon into starch and lignins. The data show that aminoglycoside antibiotics, such as kanamycin, and polyamines impinge upon this circuit. These findings provide a mechanism for the conversion of amino acid and sugar signals into an appropriate response at the gene expression level, and underline the similarities in iGluR agonism between animals and plants.