TY - JOUR A1 - Liu, Qinsong A1 - Vain, Thomas A1 - Viotti, Corrado A1 - Doyle, Siamsa M. A1 - Tarkowska, Danuse A1 - Novak, Ondrej A1 - Zipfel, Cyril A1 - Sitbon, Folke A1 - Robert, Stephanie A1 - Hofius, Daniel T1 - Vacuole integrity maintained by DUF300 proteins is required for brassinosteroid signaling regulation JF - Molecular plant N2 - Brassinosteroid (BR) hormone signaling controls multiple processes during plant growth and development and is initiated at the plasma membrane through the receptor kinase BRASSINOSTEROID INSENSITIVE1 (BRI1) together with co-receptors such as BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1). BRI1 abundance is regulated by endosomal recycling and vacuolar targeting, but the role of vacuole-related proteins in BR receptor dynamics and BR responses remains elusive. Here, we show that the absence of two DUF300 domain-containing tonoplast proteins, LAZARUS1 (LAZ1) and LAZ1 HOMOLOG1 (LAZ1H1), causes vacuole morphology defects, growth inhibition, and constitutive activation of BR signaling. Intriguingly, tonoplast accumulation of BAK1 was substantially increased and appeared causally linked to enhanced BRI1 trafficking and degradation in laz1 laz1h1 plants. Since unrelated vacuole mutants exhibited normal BR responses, our findings indicate that DUF300 proteins play distinct roles in the regulation of BR signaling by maintaining vacuole integrity required to balance subcellular BAK1 pools and BR receptor distribution. KW - brassinosteroid signaling KW - vacuole integrity KW - DUF300 proteins KW - tonoplast KW - Arabidopsis Y1 - 2018 U6 - https://doi.org/10.1016/j.molp.2017.12.015 SN - 1674-2052 SN - 1752-9867 VL - 11 IS - 4 SP - 553 EP - 567 PB - Cell Press CY - Cambridge ER - TY - JOUR A1 - Shubchynskyy, Volodymyr A1 - Boniecka, Justyna A1 - Schweighofer, Alois A1 - Simulis, Justinas A1 - Kvederaviciute, Kotryna A1 - Stumpe, Michael A1 - Mauch, Felix A1 - Balazadeh, Salma A1 - Müller-Röber, Bernd A1 - Boutrot, Freddy A1 - Zipfel, Cyril A1 - Meskiene, Irute T1 - Protein phosphatase AP2C1 negatively regulates basal resistance and defense responses to Pseudomonas syringae JF - Journal of experimental botany N2 - Mitogen-activated protein kinases (MAPKs) mediate plant immune responses to pathogenic bacteria. However, less is known about the cell autonomous negative regulatory mechanism controlling basal plant immunity. We report the biological role of Arabidopsis thaliana MAPK phosphatase AP2C1 as a negative regulator of plant basal resistance and defense responses to Pseudomonas syringae. AP2C2, a closely related MAPK phosphatase, also negatively controls plant resistance. Loss of AP2C1 leads to enhanced pathogen-induced MAPK activities, increased callose deposition in response to pathogen-associated molecular patterns or to P. syringae pv. tomato (Pto) DC3000, and enhanced resistance to bacterial infection with Pto. We also reveal the impact of AP2C1 on the global transcriptional reprogramming of transcription factors during Pto infection. Importantly, ap2c1 plants show salicylic acid-independent transcriptional reprogramming of several defense genes and enhanced ethylene production in response to Pto. This study pinpoints the specificity of MAPK regulation by the different MAPK phosphatases AP2C1 and MKP1, which control the same MAPK substrates, nevertheless leading to different downstream events. We suggest that precise and specific control of defined MAPKs by MAPK phosphatases during plant challenge with pathogenic bacteria can strongly influence plant resistance. KW - Callose KW - defense genes KW - MAPK KW - MAPK phosphatase KW - PAMP KW - PP2C phosphatase KW - Pseudomonas syringae KW - salicylic acid KW - transcription factors Y1 - 2017 U6 - https://doi.org/10.1093/jxb/erw485 SN - 0022-0957 SN - 1460-2431 VL - 68 IS - 5 SP - 1169 EP - 1183 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Trost, Gerda A1 - Vi, Son Lang A1 - Czesnick, Hjördis A1 - Lange, Peggy A1 - Holton, Nick A1 - Giavalisco, Patrick A1 - Zipfel, Cyril A1 - Kappel, Christian A1 - Lenhard, Michael T1 - Arabidopsis poly(A) polymerase PAPS1 limits founder-cell recruitment to organ primordia and suppresses the salicylic acid-independent immune response downstream of EDS1/PAD4 JF - The plant journal N2 - Polyadenylation of pre-mRNAs by poly(A) polymerase (PAPS) is a critical process in eukaryotic gene expression. As found in vertebrates, plant genomes encode several isoforms of canonical nuclear PAPS enzymes. In Arabidopsis thaliana these isoforms are functionally specialized, with PAPS1 affecting both organ growth and immune response, at least in part by the preferential polyadenylation of subsets of pre-mRNAs. Here, we demonstrate that the opposite effects of PAPS1 on leaf and flower growth reflect the different identities of these organs, and identify a role for PAPS1 in the elusive connection between organ identity and growth patterns. The overgrowth of paps1 mutant petals is due to increased recruitment of founder cells into early organ primordia, and suggests that PAPS1 activity plays unique roles in influencing organ growth. By contrast, the leaf phenotype of paps1 mutants is dominated by a constitutive immune response that leads to increased resistance to the biotrophic oomycete Hyaloperonospora arabidopsidis and reflects activation of the salicylic acid-independent signalling pathway downstream of ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1)/PHYTOALEXIN DEFICIENT4 (PAD4). These findings provide an insight into the developmental and physiological basis of the functional specialization amongst plant PAPS isoforms. KW - poly(A) polymerase KW - founder-cell recruitment KW - organ growth KW - polyadenylation Y1 - 2014 U6 - https://doi.org/10.1111/tpj.12421 SN - 0960-7412 SN - 1365-313X VL - 77 IS - 5 SP - 688 EP - 699 PB - Wiley-Blackwell CY - Hoboken ER -