TY - JOUR AB - 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. AU - Tan, Shutang AU - Abas, Melinda F AU - Verstraeten, Inge AU - Glanc, Matous AU - Molnar, Gergely AU - Hajny, Jakub AU - Lasák, Pavel AU - Petřík, Ivan AU - Russinova, Eugenia AU - Petrášek, Jan AU - Novák, Ondřej AU - Pospíšil, Jiří AU - Friml, Jiří ID - 7427 IS - 3 JF - Current Biology SN - 09609822 TI - Salicylic acid targets protein phosphatase 2A to attenuate growth in plants VL - 30 ER - TY - JOUR AB - Intercellular distribution of the plant hormone auxin largely depends on the polar subcellular distribution of the plasma membrane PIN-FORMED (PIN) auxin transporters. PIN polarity switches in response to different developmental and environmental signals have been shown to redirect auxin fluxes mediating certain developmental responses. PIN phosphorylation at different sites and by different kinases is crucial for PIN function. Here we investigate the role of PIN phosphorylation during gravitropic response. Loss- and gain-of-function mutants in PINOID and related kinases but not in D6PK kinase as well as mutations mimicking constitutive dephosphorylated or phosphorylated status of two clusters of predicted phosphorylation sites partially disrupted PIN3 phosphorylation and caused defects in gravitropic bending in roots and hypocotyls. In particular, they impacted PIN3 polarity rearrangements in response to gravity and during feed-back regulation by auxin itself. Thus PIN phosphorylation, besides regulating transport activity and apical-basal targeting, is also important for the rapid polarity switches in response to environmental and endogenous signals. AU - Grones, Peter AU - Abas, Melinda F AU - Hajny, Jakub AU - Jones, Angharad AU - Waidmann, Sascha AU - Kleine Vehn, Jürgen AU - Friml, Jirí ID - 191 IS - 1 JF - Scientific Reports TI - PID/WAG-mediated phosphorylation of the Arabidopsis PIN3 auxin transporter mediates polarity switches during gravitropism VL - 8 ER - TY - JOUR AB - Intercellular flow of the phytohormone auxin underpins multiple developmental processes in plants. Plant-specific pin-formed (PIN) proteins and several phosphoglycoprotein (PGP) transporters are crucial factors in auxin transport-related development, yet the molecular function of PINs remains unknown. Here, we show that PINs mediate auxin efflux from mammalian and yeast cells without needing additional plant-specific factors. Conditional gain-of-function alleles and quantitative measurements of auxin accumulation in Arabidopsis and tobacco cultured cells revealed that the action of PINs in auxin efflux is distinct from PGP, rate-limiting, specific to auxins, and sensitive to auxin transport inhibitors. This suggests a direct involvement of PINs in catalyzing cellular auxin efflux. AU - Petrášek, Jan AU - Mravec, Jozef AU - Bouchard, Rodolphe AU - Blakeslee, Joshua AU - Melinda Abas AU - Seifertová, Daniela AU - Wiśniewska, Justyna AU - Tadele, Zerihun AU - Kubeš, Martin AU - Čovanová, Milada AU - Dhonukshe, Pankaj AU - Skůpa, Petr AU - Eva Benková AU - Perry, Lucie AU - Křeček, Pavel AU - Lee, Ok Ran AU - Fink, Gerald R AU - Geisler, Markus AU - Murphy, Angus S AU - Luschnig, Christian AU - Zažímalová, Eva AU - Jirí Friml ID - 3012 IS - 5775 JF - Science TI - PIN proteins perform a rate-limiting function in cellular auxin efflux VL - 312 ER -