The Peach RGF/GLV Signaling Peptide pCTG134 Is Involved in a Regulatory Circuit That Sustains Auxin and Ethylene Actions

In vascular plants the cell-to-cell interactions coordinating morphogenetic and physiological processes are mediated, among others, by the action of hormones, among which also short mobile peptides were recognized to have roles as signals. Such peptide hormones (PHs) are involved in defense responses, shoot and root growth, meristem homeostasis, organ abscission, nutrient signaling, hormone crosstalk and other developmental processes and act as both short and long distant ligands. In this work, the function of CTG134, a peach gene encoding a ROOT GROWTH FACTOR/GOLVEN-like PH expressed in mesocarp at the onset of ripening, was investigated for its role in mediating an auxin-ethylene crosstalk. In peach fruit, where an auxin-ethylene crosstalk mechanism is necessary to support climacteric ethylene synthesis, CTG134 expression peaked before that of ACS1 and was induced by auxin and 1-methylcyclopropene (1-MCP) treatments, whereas it was minimally affected by ethylene. In addition, the promoter of CTG134 fused with the GUS reporter highlighted activity in plant parts in which the auxin-ethylene interplay is known to occur. Arabidopsis and tobacco plants overexpressing CTG134 showed abnormal root hair growth, similar to wild-type plants treated with a synthetic form of the sulfated peptide. Moreover, in tobacco, lateral root emergence and capsule size were also affected. In Arabidopsis overexpressing lines, molecular surveys demonstrated an impaired hormonal crosstalk, resulting in a re-modulated expression of a set of genes involved in both ethylene and auxin synthesis, transport and perception. These data support the role of pCTG134 as a mediator in an auxin-ethylene regulatory circuit and open the possibility to exploit this class of ligands for the rational design of new and environmental friendly agrochemicals able to cope with a rapidly changing environment

A genetic approach reveals different modes of action of prefoldins

[EN] The prefoldin complex (PFDc) was identified in humans as a co-chaperone of the cytosolic chaperonin T-COMPLEX PROTEIN RING COMPLEX (TRiC)/CHAPERONIN CONTAINING TCP-1 (CCT). PFDc is conserved in eukaryotes and is composed of subunits PFD1-6, and PFDc-TRiC/CCT folds actin and tubulins. PFDs also participate in a wide range of cellular processes, both in the cytoplasm and in the nucleus, and their malfunction causes developmental alterations and disease in animals and altered growth and environmental responses in yeast and plants. Genetic analyses in yeast indicate that not all of their functions require the canonical complex. The lack of systematic genetic analyses in plants and animals, however, makes it difficult to discern whether PFDs participate in a process as the canonical complex or in alternative configurations, which is necessary to understand their mode of action. To tackle this question, and on the premise that the canonical complex cannot be formed if one subunit is missing, we generated an Arabidopsis (Arabidopsis thaliana) mutant deficient in the six PFDs and compared various growth and environmental responses with those of the individual mutants. In this way, we demonstrate that the PFDc is required for seed germination, to delay flowering, or to respond to high salt stress or low temperature, whereas at least two PFDs redundantly attenuate the response to osmotic stress. A coexpression analysis of differentially expressed genes in the sextuple mutant identified several transcription factors, including ABA INSENSITIVE 5 (ABI5) and PHYTOCHROME-INTERACTING FACTOR 4, acting downstream of PFDs. Furthermore, the transcriptomic analysis allowed assigning additional roles for PFDs, for instance, in response to higher temperature.This work was supported by grants from the Spanish Ministry of Economy and Competitiveness and "Agencia Estatal de Investigacion"/FEDER/European Union (BIO2013-43184-P to D.A. and M.A.B., and BIO2016-79133-P and PID2019-109925GB-I00 to D.A.). N.B.-T., A.S.-M., and A.P.-A. were recipient of Ministerio de Economia y Competitividad (BES-2014-068868), EU MSCA-IF (H2020-MSCA-IF-2016746396) and Ministerio de Educacion (FPU17/05186) fellowships, respectively.Esteve-Bruna, D.; Blanco-Touriñán, N.; Serrano-Mislata, A.; Esquinas-Ariza, RM.; Resentini, F.; Forment Millet, JJ.; Carrasco-López, C.... (2021). A genetic approach reveals different modes of action of prefoldins. Plant Physiology. 187(3):1534-1550. https://doi.org/10.1093/plphys/kiab348S15341550187

Osservatorio territoriale droga e tossicodipendenze. Il Fenomeno delle dipendenze sul territorio della ASL MI 3. Anno 2007.

Report on the state of legal and illegal substances use in the territory of the Local Healthcare Service-Mi 3, Province of Milan.Il report analizza il fenomeno delle dipendenze nel territorio della ASL Milano 2. La descrizione del fenomeno si sviluppa intorno all\u27analisi degli indicatori individuati dall\u27Osservatorio Europeo delle Dipendenze di Lisbona (OEDT): 1-uso di sostanze nella popolazione generale (questo indicatore va a rilevare i comportamenti nei confronti di alcol e sostanze psicoattive da parte della popolazione generale); 2-prevalenza d\u27uso problematico delle sostanze psicoattive; 3-domanda di trattamento degli utilizzatori di sostanze; 4-mortalit? degli utilizzatori di sostanze; 5-malattie infettive. Altri due importanti indicatori che si stanno sviluppando, e che vengono qui illustrati, sono l\u27analisi delle Schede di Dimissione Ospedaliera (SDO) e gli indicatori relativi alle conseguenza sociali dell\u27uso di droghe (criminalit? droga correlata). Inoltre sono state applicate diverse metodologie standard di stima sia per quantificare la quota parte sconosciuta di utilizzatori di sostanze che non afferiscono ai servizi, sia per identificarne alcune caratteristiche

Illuminating the hidden world of calcium ions in plants with a universe of indicators

none6openGrenzi, Matteo; Resentini, Francesca; Vanneste, Steffen; Zottini, Michela; Bassi, Andrea; Costa, AlexGrenzi, Matteo; Resentini, Francesca; Vanneste, Steffen; Zottini, Michela; Bassi, Andrea; Costa, Ale

Evaluation of Genetic Variability among Three <i>Pistacia</i> Species Using Internal Transcribed Spacer 1 (ITS1) Marker

Diversity in Pistacia has been evaluated at all molecular levels using the internal transcribed spacer 1 (ITS1) marker in three species (Pistacia atlantica subsp. atlantica; Pistacia vera and Pistacia terebinthus), and compared with other Pistacia species. Results showed that the ITS amplification and sequencing, followed by phylogenetic analyses, identify the species and confirm their classification, which revealed that it can be used as a marker. Our results suggest that ITS1 analyses might provide a simple and inexpensive approach to validate the species of samples collected from the natural population, where species identification can be difficult, especially if hybrids are present or if the season is not optimal for identifying differences in morphological traits

SUPPRESSOR OF FRIGIDA (SUF4) Supports Gamete Fusion via Regulating Arabidopsis EC1 Gene Expression

The EGG CELL1 (EC1) gene family of Arabidopsis (Arabidopsis thaliana) comprises five members that are specifically expressed in the egg cell and redundantly control gamete fusion during double fertilization. We investigated the activity of all five EC1 promoters in promoter-deletion studies and identified SUF4 (SUPPRESSOR OF FRIGIDA4), a C2H2 transcription factor, as a direct regulator of the EC1 gene expression. In particular, we demonstrated that SUF4 binds to all five Arabidopsis EC1 promoters, thus regulating their expression. The down-regulation of SUF4 in homozygous suf4-1 ovules results in reduced EC1 expression and delayed sperm fusion, which can be rescued by expressing SUF4-b-glucuronidase under the control of the SUF4 promoter. To identify more gene products able to regulate EC1 expression together with SUF4, we performed coexpression studies that led to the identification of MOM1 (MORPHEUS' MOLECULE1), a component of a silencing mechanism that is independent of DNA methylation marks. In mom1-3 ovules, both SUF4 and EC1 genes are down-regulated, and EC1 genes show higher levels of histone 3 lysine-9 acetylation, suggesting that MOM1 contributes to the regulation of SUF4 and EC1 gene expression

The MPK8-TCP14 pathway promotes seed germination in Arabidopsis

[EN] The accurate control of dormancy release and germination is critical for successful plantlet establishment. Investigations in cereals hypothesized a crucial role for specific MAP kinase (MPK) pathways in promoting dormancy release, although the identity of the MPK involved and the downstream events remain unclear. In this work, we characterized mutants for Arabidopsis thaliana MAP kinase 8 (MPK8). Mpk8 seeds presented a deeper dormancy than wild-type (WT) at harvest that was less efficiently alleviated by after-ripening and gibberellic acid treatment. We identified Teosinte Branched1/Cycloidea/Proliferating cell factor 14 (TCP14), a transcription factor regulating germination, as a partner of MPK8. Mpk8 tcp14 double-mutant seeds presented a deeper dormancy at harvest than WT and mpk8, but similar to that of tcp14 seeds. MPK8 interacted with TCP14 in the nucleus in vivo and phosphorylated TCP14 in vitro. Furthermore, MPK8 enhanced TCP14 transcriptional activity when co-expressed in tobacco leaves. Nevertheless, the stimulation of TCP14 transcriptional activity by MPK8 could occur independently of TCP14 phosphorylation. The comparison of WT, mpk8 and tcp14 transcriptomes evidenced that whereas no effect was observed in dry seeds, mpk8 and tcp14 mutants presented dramatic transcriptomic alterations after imbibition with a sustained expression of genes related to seed maturation. Moreover, both mutants exhibited repression of genes involved in cell wall remodeling and cell cycle G1/S transition. As a whole, this study unraveled a role for MPK8 in promoting seed germination, and suggested that its interaction with TCP14 was critical for regulating key processes required for germination completion.This work was supported by the Chinese Scholarship Council (201606690037 to WZ), CNRS, Sorbonne Universite and the LabEx Saclay Plant Sciences-SPS (ANR-10-LABX-0040-SPS). The authors acknowledge Jean Francois Gilles from the IBPS imaging core facility, which is supported by Conseil Regional Ile-de-France, for help with confocal microscopy. The authors thank Cristina Urbez (CSIC-U Politecnica de Valencia) for technical assistance. The authors thank Pr Brendan Davies (University of Leeds) for providing tcp14.4 seeds, and Dr Jean Colcombet (IPS2 Universite Paris-Saclay) for providing MPK8-pDONOR vector.Zhang, W.; Cochet, F.; Ponnaiah, M.; Lebreton, S.; Matheron, L.; Pionneau, C.; Boudsocq, M.... (2019). The MPK8-TCP14 pathway promotes seed germination in Arabidopsis. The Plant Journal. 100(4):677-692. https://doi.org/10.1111/tpj.14461S6776921004Barrôco, R. M., Van Poucke, K., Bergervoet, J. H. W., De Veylder, L., Groot, S. P. C., Inzé, D., & Engler, G. (2005). The Role of the Cell Cycle Machinery in Resumption of Postembryonic Development. Plant Physiology, 137(1), 127-140. doi:10.1104/pp.104.049361Basbouss-Serhal, I., Soubigou-Taconnat, L., Bailly, C., & Leymarie, J. (2015). Germination Potential of Dormant and Nondormant Arabidopsis Seeds Is Driven by Distinct Recruitment of Messenger RNAs to Polysomes. Plant Physiology, 168(3), 1049-1065. doi:10.1104/pp.15.00510Bassel, G. W., Lan, H., Glaab, E., Gibbs, D. J., Gerjets, T., Krasnogor, N., … Provart, N. J. (2011). Genome-wide network model capturing seed germination reveals coordinated regulation of plant cellular phase transitions. Proceedings of the National Academy of Sciences, 108(23), 9709-9714. doi:10.1073/pnas.1100958108Boudsocq, M., Droillard, M.-J., Regad, L., & Laurière, C. (2012). Characterization of Arabidopsis calcium-dependent protein kinases: activated or not by calcium? Biochemical Journal, 447(2), 291-299. doi:10.1042/bj20112072Chang, S., Puryear, J., & Cairney, J. (1993). A simple and efficient method for isolating RNA from pine trees. Plant Molecular Biology Reporter, 11(2), 113-116. doi:10.1007/bf02670468Colcombet, J., & Hirt, H. (2008). Arabidopsis MAPKs: a complex signalling network involved in multiple biological processes. Biochemical Journal, 413(2), 217-226. doi:10.1042/bj20080625Cutler, S. R., Rodriguez, P. L., Finkelstein, R. R., & Abrams, S. R. (2010). Abscisic Acid: Emergence of a Core Signaling Network. Annual Review of Plant Biology, 61(1), 651-679. doi:10.1146/annurev-arplant-042809-112122Dai, C., & Xue, H.-W. (2010). Rice early flowering1, a CKI, phosphorylates DELLA protein SLR1 to negatively regulate gibberellin signalling. The EMBO Journal, 29(11), 1916-1927. doi:10.1038/emboj.2010.75Danquah, A., de Zélicourt, A., Boudsocq, M., Neubauer, J., Frei dit Frey, N., Leonhardt, N., … Colcombet, J. (2015). Identification and characterization of an ABA-activated MAP kinase cascade inArabidopsis thaliana. The Plant Journal, 82(2), 232-244. doi:10.1111/tpj.12808Davière, J.-M., & Achard, P. (2016). A Pivotal Role of DELLAs in Regulating Multiple Hormone Signals. Molecular Plant, 9(1), 10-20. doi:10.1016/j.molp.2015.09.011Davière, J.-M., Wild, M., Regnault, T., Baumberger, N., Eisler, H., Genschik, P., & Achard, P. (2014). Class I TCP-DELLA Interactions in Inflorescence Shoot Apex Determine Plant Height. Current Biology, 24(16), 1923-1928. doi:10.1016/j.cub.2014.07.012Dóczi, R., & Bögre, L. (2018). The Quest for MAP Kinase Substrates: Gaining Momentum. Trends in Plant Science, 23(10), 918-932. doi:10.1016/j.tplants.2018.08.002Edgar, R. (2002). Gene Expression Omnibus: NCBI gene expression and hybridization array data repository. Nucleic Acids Research, 30(1), 207-210. doi:10.1093/nar/30.1.207Finkelstein, R., Reeves, W., Ariizumi, T., & Steber, C. (2008). Molecular Aspects of Seed Dormancy. Annual Review of Plant Biology, 59(1), 387-415. doi:10.1146/annurev.arplant.59.032607.092740Fujii, H., & Zhu, J.-K. (2009). Arabidopsis mutant deficient in 3 abscisic acid-activated protein kinases reveals critical roles in growth, reproduction, and stress. Proceedings of the National Academy of Sciences, 106(20), 8380-8385. doi:10.1073/pnas.0903144106Fujii, H., Chinnusamy, V., Rodrigues, A., Rubio, S., Antoni, R., Park, S.-Y., … Zhu, J.-K. (2009). In vitro reconstitution of an abscisic acid signalling pathway. Nature, 462(7273), 660-664. doi:10.1038/nature08599Gagnot, S., Tamby, J.-P., Martin-Magniette, M.-L., Bitton, F., Taconnat, L., Balzergue, S., … Brunaud, V. (2007). CATdb: a public access to Arabidopsis transcriptome data from the URGV-CATMA platform. Nucleic Acids Research, 36(Database), D986-D990. doi:10.1093/nar/gkm757García-Alvarez, G., Ventura, V., Ros, O., Aligué, R., Gil, J., & Tauler, A. (2007). Glycogen synthase kinase-3β binds to E2F1 and regulates its transcriptional activity. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1773(3), 375-382. doi:10.1016/j.bbamcr.2006.09.015GRAEBER, K., NAKABAYASHI, K., MIATTON, E., LEUBNER-METZGER, G., & SOPPE, W. J. J. (2012). Molecular mechanisms of seed dormancy. Plant, Cell & Environment, 35(10), 1769-1786. doi:10.1111/j.1365-3040.2012.02542.xHussain, A., Cao, D., Cheng, H., Wen, Z., & Peng, J. (2005). Identification of the conserved serine/threonine residues important for gibberellin-sensitivity of Arabidopsis RGL2 protein. The Plant Journal, 44(1), 88-99. doi:10.1111/j.1365-313x.2005.02512.xKieffer, M., Master, V., Waites, R., & Davies, B. (2011). TCP14 and TCP15 affect internode length and leaf shape in Arabidopsis. The Plant Journal, 68(1), 147-158. doi:10.1111/j.1365-313x.2011.04674.xKim, S. H., Son, G. H., Bhattacharjee, S., Kim, H. J., Nam, J. C., Nguyen, P. D. T., … Gassmann, W. (2014). The Arabidopsis immune adaptor SRFR1 interacts with TCP transcription factors that redundantly contribute to effector-triggered immunity. The Plant Journal, 78(6), 978-989. doi:10.1111/tpj.12527Kung, J. E., & Jura, N. (2016). Structural Basis for the Non-catalytic Functions of Protein Kinases. Structure, 24(1), 7-24. doi:10.1016/j.str.2015.10.020Langella, O., Valot, B., Balliau, T., Blein-Nicolas, M., Bonhomme, L., & Zivy, M. (2016). X!TandemPipeline: A Tool to Manage Sequence Redundancy for Protein Inference and Phosphosite Identification. Journal of Proteome Research, 16(2), 494-503. doi:10.1021/acs.jproteome.6b00632Lee, S., Lee, M. H., Kim, J.-I., & Kim, S. Y. (2014). Arabidopsis Putative MAP Kinase Kinase Kinases Raf10 and Raf11 are Positive Regulators of Seed Dormancy and ABA Response. Plant and Cell Physiology, 56(1), 84-97. doi:10.1093/pcp/pcu148López-Bucio, J. S., Dubrovsky, J. G., Raya-González, J., Ugartechea-Chirino, Y., López-Bucio, J., de Luna-Valdez, L. A., … Guevara-García, A. A. (2013). Arabidopsis thaliana mitogen-activated protein kinase 6 is involved in seed formation and modulation of primary and lateral root development. Journal of Experimental Botany, 65(1), 169-183. doi:10.1093/jxb/ert368Matheron, L., van den Toorn, H., Heck, A. J. R., & Mohammed, S. (2014). Characterization of Biases in Phosphopeptide Enrichment by Ti4+-Immobilized Metal Affinity Chromatography and TiO2 Using a Massive Synthetic Library and Human Cell Digests. Analytical Chemistry, 86(16), 8312-8320. doi:10.1021/ac501803zNagy, S. K., Darula, Z., Kállai, B. M., Bögre, L., Bánhegyi, G., Medzihradszky, K. F., … Mészáros, T. (2015). Activation of AtMPK9 through autophosphorylation that makes it independent of the canonical MAPK cascades. Biochemical Journal, 467(1), 167-175. doi:10.1042/bj20141176Nakashima, K., Fujita, Y., Kanamori, N., Katagiri, T., Umezawa, T., Kidokoro, S., … Yamaguchi-Shinozaki, K. (2009). Three Arabidopsis SnRK2 Protein Kinases, SRK2D/SnRK2.2, SRK2E/SnRK2.6/OST1 and SRK2I/SnRK2.3, Involved in ABA Signaling are Essential for the Control of Seed Development and Dormancy. Plant and Cell Physiology, 50(7), 1345-1363. doi:10.1093/pcp/pcp083Nguyen, X. C., Hoang, M. H. T., Kim, H. S., Lee, K., Liu, X.-M., Kim, S. H., … Chung, W. S. (2012). Phosphorylation of the transcriptional regulator MYB44 by mitogen activated protein kinase regulates Arabidopsis seed germination. Biochemical and Biophysical Research Communications, 423(4), 703-708. doi:10.1016/j.bbrc.2012.06.019Nicolas, M., & Cubas, P. (2016). TCP factors: new kids on the signaling block. Current Opinion in Plant Biology, 33, 33-41. doi:10.1016/j.pbi.2016.05.006Ogawa, M., Hanada, A., Yamauchi, Y., Kuwahara, A., Kamiya, Y., & Yamaguchi, S. (2003). Gibberellin Biosynthesis and Response during Arabidopsis Seed Germination[W]. The Plant Cell, 15(7), 1591-1604. doi:10.1105/tpc.011650Penfield, S. (2017). Seed dormancy and germination. Current Biology, 27(17), R874-R878. doi:10.1016/j.cub.2017.05.050Popescu, S. C., Popescu, G. V., Bachan, S., Zhang, Z., Gerstein, M., Snyder, M., & Dinesh-Kumar, S. P. (2008). MAPK target networks in Arabidopsis thaliana revealed using functional protein microarrays. Genes & Development, 23(1), 80-92. doi:10.1101/gad.1740009Resentini, F., Felipo-Benavent, A., Colombo, L., Blázquez, M. A., Alabadí, D., & Masiero, S. (2015). TCP14 and TCP15 Mediate the Promotion of Seed Germination by Gibberellins in Arabidopsis thaliana. Molecular Plant, 8(3), 482-485. doi:10.1016/j.molp.2014.11.018Rueda-Romero, P., Barrero-Sicilia, C., Gómez-Cadenas, A., Carbonero, P., & Oñate-Sánchez, L. (2011). Arabidopsis thaliana DOF6 negatively affects germination in non-after-ripened seeds and interacts with TCP14. Journal of Experimental Botany, 63(5), 1937-1949. doi:10.1093/jxb/err388Sechet, J., Frey, A., Effroy-Cuzzi, D., Berger, A., Perreau, F., Cueff, G., … Marion-Poll, A. (2016). Xyloglucan Metabolism Differentially Impacts the Cell Wall Characteristics of the Endosperm and Embryo during Arabidopsis Seed Germination. Plant Physiology, 170(3), 1367-1380. doi:10.1104/pp.15.01312Shu, K., Liu, X., Xie, Q., & He, Z. (2016). Two Faces of One Seed: Hormonal Regulation of Dormancy and Germination. Molecular Plant, 9(1), 34-45. doi:10.1016/j.molp.2015.08.010Siloto, R. M. P., Findlay, K., Lopez-Villalobos, A., Yeung, E. C., Nykiforuk, C. L., & Moloney, M. M. (2006). The Accumulation of Oleosins Determines the Size of Seed Oilbodies inArabidopsis. The Plant Cell, 18(8), 1961-1974. doi:10.1105/tpc.106.041269Takahashi, F., Mizoguchi, T., Yoshida, R., Ichimura, K., & Shinozaki, K. (2011). Calmodulin-Dependent Activation of MAP Kinase for ROS Homeostasis in Arabidopsis. Molecular Cell, 41(6), 649-660. doi:10.1016/j.molcel.2011.02.029Tatematsu, K., Nakabayashi, K., Kamiya, Y., & Nambara, E. (2008). Transcription factor AtTCP14 regulates embryonic growth potential during seed germination inArabidopsis thaliana. The Plant Journal, 53(1), 42-52. doi:10.1111/j.1365-313x.2007.03308.xTorada, A., Koike, M., Ogawa, T., Takenouchi, Y., Tadamura, K., Wu, J., … Ogihara, Y. (2016). A Causal Gene for Seed Dormancy on Wheat Chromosome 4A Encodes a MAP Kinase Kinase. Current Biology, 26(6), 782-787. doi:10.1016/j.cub.2016.01.063Umezawa, T., Sugiyama, N., Mizoguchi, M., Hayashi, S., Myouga, F., Yamaguchi-Shinozaki, K., … Shinozaki, K. (2009). Type 2C protein phosphatases directly regulate abscisic acid-activated protein kinases in Arabidopsis. Proceedings of the National Academy of Sciences, 106(41), 17588-17593. doi:10.1073/pnas.0907095106Valsecchi, I., Guittard-Crilat, E., Maldiney, R., Habricot, Y., Lignon, S., Lebrun, R., … Lebreton, S. (2013). The intrinsically disordered C-terminal region of Arabidopsis thaliana TCP8 transcription factor acts both as a transactivation and self-assembly domain. Molecular BioSystems, 9(9), 2282. doi:10.1039/c3mb70128jVelappan, Y., Signorelli, S., & Considine, M. J. (2017). Cell cycle arrest in plants: what distinguishes quiescence, dormancy and differentiated G1? Annals of Botany, 120(4), 495-509. doi:10.1093/aob/mcx082Vizcaíno, J. A., Côté, R. G., Csordas, A., Dianes, J. A., Fabregat, A., Foster, J. M., … Hermjakob, H. (2012). The Proteomics Identifications (PRIDE) database and associated tools: status in 2013. Nucleic Acids Research, 41(D1), D1063-D1069. doi:10.1093/nar/gks1262Xu, J., & Zhang, S. (2015). Mitogen-activated protein kinase cascades in signaling plant growth and development. Trends in Plant Science, 20(1), 56-64. doi:10.1016/j.tplants.2014.10.001Yang, L., Teixeira, P. J. P. L., Biswas, S., Finkel, O. M., He, Y., Salas-Gonzalez, I., … Dangl, J. L. (2017). Pseudomonas syringae Type III Effector HopBB1 Promotes Host Transcriptional Repressor Degradation to Regulate Phytohormone Responses and Virulence. Cell Host & Microbe, 21(2), 156-168. doi:10.1016/j.chom.2017.01.00