Plants, like other multicellular organisms, survive through a delicate balance between growth and defense against pathogens. Salicylic acid (SA) is a major defense signal in plants, and the perception mechanism as well as downstream signaling activating the immune response are known. Here, we identify a parallel SA signaling that mediates growth attenuation. SA directly binds to A subunits of protein phosphatase 2A (PP2A), inhibiting activity of this complex. Among PP2A targets, the PIN2 auxin transporter is hyperphosphorylated in response to SA, leading to changed activity of this important growth regulator. Accordingly, auxin transport and auxin-mediated root development, including growth, gravitropic response, and lateral root organogenesis, are inhibited. This study reveals how SA, besides activating immunity, concomitantly attenuates growth through crosstalk with the auxin distribution network. Further analysis of this dual role of SA and characterization of additional SA-regulated PP2A targets will provide further insights into mechanisms maintaining a balance between growth and defense.

• MeSH
• Arabidopsis růst a vývoj   fyziologie   MeSH
• imunita rostlin MeSH
• kořeny rostlin růst a vývoj   metabolismus   MeSH
• kyselina salicylová metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• proteinfosfatasa 2 metabolismus   MeSH
• proteiny huseníčku metabolismus   MeSH
• signální transdukce * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Auxin is unique among plant hormones due to its directional transport that is mediated by the polarly distributed PIN auxin transporters at the plasma membrane. The canalization hypothesis proposes that the auxin feedback on its polar flow is a crucial, plant-specific mechanism mediating multiple self-organizing developmental processes. Here, we used the auxin effect on the PIN polar localization in Arabidopsis thaliana roots as a proxy for the auxin feedback on the PIN polarity during canalization. We performed microarray experiments to find regulators of this process that act downstream of auxin. We identified genes that were transcriptionally regulated by auxin in an AXR3/IAA17- and ARF7/ARF19-dependent manner. Besides the known components of the PIN polarity, such as PID and PIP5K kinases, a number of potential new regulators were detected, among which the WRKY23 transcription factor, which was characterized in more detail. Gain- and loss-of-function mutants confirmed a role for WRKY23 in mediating the auxin effect on the PIN polarity. Accordingly, processes requiring auxin-mediated PIN polarity rearrangements, such as vascular tissue development during leaf venation, showed a higher WRKY23 expression and required the WRKY23 activity. Our results provide initial insights into the auxin transcriptional network acting upstream of PIN polarization and, potentially, canalization-mediated plant development.

• MeSH
• Arabidopsis genetika   růst a vývoj   MeSH
• geneticky modifikované rostliny MeSH
• genové regulační sítě * účinky léků   MeSH
• kořeny rostlin účinky léků   genetika   růst a vývoj   metabolismus   MeSH
• kyseliny indoloctové metabolismus   farmakologie   MeSH
• membránové transportní proteiny genetika   metabolismus   MeSH
• mikročipová analýza MeSH
• polarita buněk * genetika   MeSH
• proteiny huseníčku genetika   metabolismus   fyziologie   MeSH
• regulace genové exprese u rostlin účinky léků   MeSH
• stanovení celkové genové exprese MeSH
• transkripční faktory fyziologie   MeSH
• zpětná vazba fyziologická účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH