05.04.2022: Jiri FRIML (IST Austria): Non-canonical auxin signaling in plant development, HS 32.01, Institut für Biologie, Bereich für Pflanzenwissenschaften, Holteigasse 6, 17:00 Uhr.
The plant hormone auxin is a versatile intercellular signal influencing virtually all aspects of plant life. It has a unique ability to be directionally transported within tissues forming local auxin maxima or gradients that are central to many developmental processes mediated by auxin. One of the key roles of auxin is adaptation of plant growth to gravity, where shoots bend up and roots down. This paradox is based on opposite responses of these organs to the phytohormone auxin, which promotes cell expansion in shoots, while inhibiting it in roots via an unclear signaling pathway and yet unknown downstream cellular mechanism.
The well-established canonical auxin signaling involving the TIR1/AFB auxin receptors, Aux/IAA repressors and ARF transcription factors acts in nucleus and mediates gene transcription. However, auxin also triggers cellular responses within seconds or minutes, too fast to rely on transcription. Part of the rapid responses is mediated by the non-transcriptional branch of the TIR1/AFB signaling, but others involve a yet completely unknown mechanism.
Here I will present new insights into the mechanism of non-transcriptional auxin signaling including an ultrafast auxin-triggered protein phosphorylation response in Arabidopsis roots that is largely independent of the canonical TIR1/AFB receptors.