The plant-signaling molecule auxin triggers fast and slow cellular responses across land plants and algae. The nuclear auxin pathway mediates gene expression and controls growth and development in land plants, but this pathway is absent from algal sister groups. Several components of rapid responses have been identified in Arabidopsis, but it is unknown if these are part of a conserved mechanism. We recently identified a fast, proteome-wide phosphorylation response to auxin. Here, we show that this response occurs across 5 land plant and algal species and converges on a core group of shared targets. We found conserved rapid physiological responses to auxin in the same species and identified rapidly accelerated fibrosarcoma (RAF)-like protein kinases as central mediators of auxin-triggered phosphorylation across species. Genetic analysis connects this kinase to both auxin-triggered protein phosphorylation and rapid cellular response, thus identifying an ancient mechanism for fast auxin responses in the green lineage.

• Klíčová slova
• RAF kinase, auxin, plant evolution, protein phosphorylation,
• MeSH
• Arabidopsis genetika   metabolismus   MeSH
• bílkoviny řas metabolismus   MeSH
• fosforylace MeSH
• kyseliny indoloctové metabolismus   MeSH
• proteinkinasy metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné proteiny metabolismus   MeSH
• rostliny metabolismus   MeSH
• signální transdukce * MeSH
• vyšší rostliny * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bílkoviny řas MeSH
• kyseliny indoloctové MeSH
• proteinkinasy MeSH
• rostlinné proteiny MeSH

The phytohormone auxin triggers transcriptional reprogramming through a well-characterized perception machinery in the nucleus. By contrast, mechanisms that underlie fast effects of auxin, such as the regulation of ion fluxes, rapid phosphorylation of proteins or auxin feedback on its transport, remain unclear1-3. Whether auxin-binding protein 1 (ABP1) is an auxin receptor has been a source of debate for decades1,4. Here we show that a fraction of Arabidopsis thaliana ABP1 is secreted and binds auxin specifically at an acidic pH that is typical of the apoplast. ABP1 and its plasma-membrane-localized partner, transmembrane kinase 1 (TMK1), are required for the auxin-induced ultrafast global phospho-response and for downstream processes that include the activation of H+-ATPase and accelerated cytoplasmic streaming. abp1 and tmk mutants cannot establish auxin-transporting channels and show defective auxin-induced vasculature formation and regeneration. An ABP1(M2X) variant that lacks the capacity to bind auxin is unable to complement these defects in abp1 mutants. These data indicate that ABP1 is the auxin receptor for TMK1-based cell-surface signalling, which mediates the global phospho-response and auxin canalization.

• MeSH
• Arabidopsis * genetika   metabolismus   MeSH
• fosforylace MeSH
• koncentrace vodíkových iontů MeSH
• kyseliny indoloctové * metabolismus   MeSH
• mutace MeSH
• protein-serin-threoninkinasy * genetika   metabolismus   MeSH
• proteiny huseníčku * genetika   metabolismus   MeSH
• protonové ATPasy metabolismus   MeSH
• proudění cytoplazmy MeSH
• regulátory růstu rostlin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• AT1G66150 protein, Arabidopsis MeSH Prohlížeč
• auxin-binding protein 1 MeSH Prohlížeč
• kyseliny indoloctové * MeSH
• protein-serin-threoninkinasy * MeSH
• proteiny huseníčku * MeSH
• protonové ATPasy MeSH
• regulátory růstu rostlin MeSH