Single-cell resolution of lineage trajectories in the Arabidopsis stomatal lineage and developing leaf

Dynamic cell identities underlie flexible developmental programs. The stomatal lineage in the Arabidopsis leaf epidermis features asynchronous and indeterminate divisions that can be modulated by environmental cues. The products of the lineage, stomatal guard cells and pavement cells, regulate plant-atmosphere exchanges, and the epidermis as a whole influences overall leaf growth. How flexibility is encoded in development of the stomatal lineage and how cell fates are coordinated in the leaf are open questions. Here, by leveraging single-cell transcriptomics and molecular genetics, we uncovered models of cell differentiation within Arabidopsis leaf tissue. Profiles across leaf tissues identified points of regulatory congruence. In the stomatal lineage, single-cell resolution resolved underlying cell heterogeneity within early stages and provided a fine-grained profile of guard cell differentiation. Through integration of genome-scale datasets and spatiotemporally precise functional manipulations, we also identified an extended role for the transcriptional regulator SPEECHLESS in reinforcing cell fate commitment.Peer reviewe

Tightening the pores to unload the phloem

Root growth depends on the shoot-to-root transport of assimilates through the phloem, which is connected to the meristems by plasmodesmata pores. A PHLOEM UNLOADING MODULATOR is now identified to regulate plasmodesmata internal organisation, leading to pores that appear tighter but are more efficient for transport

A phylogenetic approach to study the origin and evolution of plasmodesmata-localized glycosyl hydrolases family 17.

Colonization of the land by plants required major modifications in cellular structural composition and metabolism. Intercellular communication through plasmodesmata (PD) plays a critical role in the coordination of growth and cell activities. Changes in the form, regulation or function of these channels are likely linked to plant adaptation to the terrestrial environments. Constriction of PD aperture by deposition of callose is the best-studied mechanism in PD regulation. Glycosyl hydrolases family 17 (GHL17) are callose degrading enzymes. In Arabidopsis this is a large protein family, few of which have been PD-localized. The objective here is to identify correlations between evolution of this protein family and their role at PD and to use this information as a tool to predict the localization of candidates isolated in a proteomic screen. With this aim, we studied phylogenetic relationship between Arabidopsis GHL17 sequences and those isolated from fungi, green algae, mosses and monocot representatives. Three distinct phylogenetic clades were identified. Clade alpha contained only embryophytes sequences suggesting that this subgroup appeared during land colonization in organisms with functional PD. Accordingly, all PD-associated GHL17 proteins identified so far in Arabidopsis thaliana and Populus are grouped in this 'embryophytes only' phylogenetic clade. Next, we tested the use of this knowledge to discriminate between candidates isolated in the PD proteome. Transient and stable expression of GFP protein fusions confirmed PD localization for candidates contained in clade alpha but not for candidates contained in clade beta. Our results suggest that GHL17 membrane proteins contained in the alpha clade evolved and expanded during land colonization to play new roles, among others, in PD regulation

Hexanoic Acid Treatment Prevents Systemic MNSV Movement in Cucumis melo Plants by Priming Callose Deposition Correlating SA and OPDA Accumulation

[EN] Unlike fungal and bacterial diseases, no direct method is available to control viral diseases. The use of resistance-inducing compounds can be an alternative strategy for plant viruses. Here we studied the basal response of melon to Melon necrotic spot virus (MNSV) and demonstrated the efficacy of hexanoic acid (Hx) priming, which prevents the virus from systemically spreading. We analysed callose deposition and the hormonal profile and gene expression at the whole plant level. This allowed us to determine hormonal homeostasis in the melon roots, cotyledons, hypocotyls, stems and leaves involved in basal and hexanoic acid-induced resistance (Hx-IR) to MNSV. Our data indicate important roles of salicylic acid (SA), 12-oxo-phytodienoic acid (OPDA), jasmonic-isoleucine, and ferulic acid in both responses to MNSV. The hormonal and metabolites balance, depending on the time and location associated with basal and Hx-IR, demonstrated the reprogramming of plant metabolism in MNSV-inoculated plants. The treatment with both SA and OPDA prior to virus infection significantly reduced MNSV systemic movement by inducing callose deposition. This demonstrates their relevance in Hx-IR against MNSV and a high correlation with callose deposition. Our data also provide valuable evidence to unravel priming mechanisms by natural compounds.This work has been supported by grants from the Spanish Ministry of Science and Innovation (AGL2010-22300-C03-01-02, AGL2013-49023-C03-01-02-R and BIO2014-54862-R), co-funded by the European Regional Development Fund.Fernandez-Crespo, E.; Navarro Bohigues, JA.; Serra Soriano, M.; Finiti, I.; García Agustín, P.; Pallás Benet, V.; Gonzalez-Bosch, C. (2017). Hexanoic Acid Treatment Prevents Systemic MNSV Movement in Cucumis melo Plants by Priming Callose Deposition Correlating SA and OPDA Accumulation. Frontiers in Plant Science. 8:1-15. https://doi.org/10.3389/fpls.2017.01793S1158Alazem, M., & Lin, N. (2014). Roles of plant hormones in the regulation of host–virus interactions. Molecular Plant Pathology, 16(5), 529-540. doi:10.1111/mpp.12204Ando, S., Obinata, A., & Takahashi, H. (2014). WRKY70 interacting with RCY1 disease resistance protein is required for resistance to Cucumber mosaic virus in Arabidopsis thaliana. Physiological and Molecular Plant Pathology, 85, 8-14. doi:10.1016/j.pmpp.2013.11.001Anfoka, G. H. (2000). Benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester induces systemic resistance in tomato (Lycopersicon esculentum. Mill cv. Vollendung) to Cucumber mosaic virus. Crop Protection, 19(6), 401-405. doi:10.1016/s0261-2194(00)00031-4Aranega-Bou, P., de la O Leyva, M., Finiti, I., García-Agustín, P., & González-Bosch, C. (2014). Priming of plant resistance by natural compounds. Hexanoic acid as a model. Frontiers in Plant Science, 5. doi:10.3389/fpls.2014.00488Bellés, J. M., López-Gresa, M. P., Fayos, J., Pallás, V., Rodrigo, I., & Conejero, V. (2008). Induction of cinnamate 4-hydroxylase and phenylpropanoids in virus-infected cucumber and melon plants. Plant Science, 174(5), 524-533. doi:10.1016/j.plantsci.2008.02.008Bolwell, G. P., Davies, D. R., Gerrish, C., Auh, C.-K., & Murphy, T. M. (1998). Comparative Biochemistry of the Oxidative Burst Produced by Rose and French Bean Cells Reveals Two Distinct Mechanisms. Plant Physiology, 116(4), 1379-1385. doi:10.1104/pp.116.4.1379Camañes, G., Scalschi, L., Vicedo, B., González-Bosch, C., & García-Agustín, P. (2015). An untargeted global metabolomic analysis reveals the biochemical changes underlying basal resistance and priming in Solanum lycopersicum, and identifies 1-methyltryptophan as a metabolite involved in plant responses to Botrytis cinerea and Pseudomonas sy. The Plant Journal, 84(1), 125-139. doi:10.1111/tpj.12964Clarke, S. F., Guy, P. L., Burritt, D. J., & Jameson, P. E. (2002). Changes in the activities of antioxidant enzymes in response to virus infection and hormone treatment. Physiologia Plantarum, 114(2), 157-164. doi:10.1034/j.1399-3054.2002.1140201.xCollum, T. D., & Culver, J. N. (2016). The impact of phytohormones on virus infection and disease. Current Opinion in Virology, 17, 25-31. doi:10.1016/j.coviro.2015.11.003Conti, G., Rodriguez, M. C., Venturuzzi, A. L., & Asurmendi, S. (2016). Modulation of host plant immunity by Tobamovirus proteins. Annals of Botany, mcw216. doi:10.1093/aob/mcw216Culver, J. N., & Padmanabhan, M. S. (2007). Virus-Induced Disease: Altering Host Physiology One Interaction at a Time. Annual Review of Phytopathology, 45(1), 221-243. doi:10.1146/annurev.phyto.45.062806.094422Dong, C.-J., Li, L., Shang, Q.-M., Liu, X.-Y., & Zhang, Z.-G. (2014). Endogenous salicylic acid accumulation is required for chilling tolerance in cucumber (Cucumis sativus L.) seedlings. Planta, 240(4), 687-700. doi:10.1007/s00425-014-2115-1Ellinger, D., Naumann, M., Falter, C., Zwikowics, C., Jamrow, T., Manisseri, C., … Voigt, C. A. (2013). Elevated Early Callose Deposition Results in Complete Penetration Resistance to Powdery Mildew in Arabidopsis. Plant Physiology, 161(3), 1433-1444. doi:10.1104/pp.112.211011Finiti, I., de la O. Leyva, M., Vicedo, B., Gómez-Pastor, R., López-Cruz, J., García-Agustín, P., … González-Bosch, C. (2014). Hexanoic acid protects tomato plants againstBotrytis cinereaby priming defence responses and reducing oxidative stress. Molecular Plant Pathology, 15(6), 550-562. doi:10.1111/mpp.12112Flors, V., Leyva, M. de la O., Vicedo, B., Finiti, I., Real, M. D., García-Agustín, P., … González-Bosch, C. (2007). Absence of the endo-β-1,4-glucanases Cel1 and Cel2 reduces susceptibility toBotrytis cinereain tomato. The Plant Journal, 52(6), 1027-1040. doi:10.1111/j.1365-313x.2007.03299.xFlors, V., Ton, J., Van Doorn, R., Jakab, G., García-Agustín, P., & Mauch-Mani, B. (2007). Interplay between JA, SA and ABA signalling during basal and induced resistance against Pseudomonas syringae and Alternaria brassicicola. The Plant Journal, 54(1), 81-92. doi:10.1111/j.1365-313x.2007.03397.xFriedrich, L., Lawton, K., Ruess, W., Masner, P., Specker, N., Rella, M. G., … Ryals, J. (1996). A benzothiadiazole derivative induces systemic acquired resistance in tobacco. The Plant Journal, 10(1), 61-70. doi:10.1046/j.1365-313x.1996.10010061.xFurch, A. C. U., Zimmermann, M. R., Kogel, K.-H., Reichelt, M., & Mithöfer, A. (2014). 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A self-interacting carmovirus movement protein plays a role in binding of viral RNA during the cell-to-cell movement and shows an actin cytoskeleton dependent location in cell periphery. Virology, 395(1), 133-142. doi:10.1016/j.virol.2009.08.042Ghoshroy, S., Freedman, K., Lartey, R., & Citovsky, V. (1998). Inhibition of plant viral systemic infection by non‐toxic concentrations of cadmium. The Plant Journal, 13(5), 591-602. doi:10.1046/j.1365-313x.1998.00061.xGosalvez, B., Navarro, J. ., Lorca, A., Botella, F., Sánchez-Pina, M. ., & Pallas, V. (2003). Detection of Melon necrotic spot virus in water samples and melon plants by molecular methods. Journal of Virological Methods, 113(2), 87-93. doi:10.1016/s0166-0934(03)00224-6GOSALVEZ‐BERNAL, B., GENOVES, A., ANTONIO NAVARRO, J., PALLAS, V., & SANCHEZ‐PINA, M. A. (2008). Distribution and pathway for phloem‐dependent movement of Melon necrotic spot virus in melon plants. Molecular Plant Pathology, 9(4), 447-461. doi:10.1111/j.1364-3703.2008.00474.xHanley-Bowdoin, L., Bejarano, E. R., Robertson, D., & Mansoor, S. (2013). Geminiviruses: masters at redirecting and reprogramming plant processes. Nature Reviews Microbiology, 11(11), 777-788. doi:10.1038/nrmicro3117Hernandez, J. A., Diaz-Vivancos, P., Rubio, M., Olmos, E., Ros-Barcelo, A., & Martinez-Gomez, P. (2006). Long-term plum pox virus infection produces an oxidative stress in a susceptible apricot, Prunus armeniaca, cultivar but not in a resistant cultivar. Physiologia Plantarum, 126(1), 140-152. doi:10.1111/j.1399-3054.2005.00581.xHipper, C., Brault, V., Ziegler-Graff, V., & Revers, F. (2013). Viral and Cellular Factors Involved in Phloem Transport of Plant Viruses. Frontiers in Plant Science, 4. doi:10.3389/fpls.2013.00154Inaba, J., Kim, B. M., Shimura, H., & Masuta, C. (2011). Virus-Induced Necrosis Is a Consequence of Direct Protein-Protein Interaction between a Viral RNA-Silencing Suppressor and a Host Catalase. Plant Physiology, 156(4), 2026-2036. doi:10.1104/pp.111.180042Lange, L., & Insunza, V. (1977). Root-inhabiting Olpidium species: The O. radicale complex. Transactions of the British Mycological Society, 69(3), 377-384. doi:10.1016/s0007-1536(77)80074-0Lee, J.-Y., Wang, X., Cui, W., Sager, R., Modla, S., Czymmek, K., … Lakshmanan, V. (2011). A Plasmodesmata-Localized Protein Mediates Crosstalk between Cell-to-Cell Communication and Innate Immunity in Arabidopsis. The Plant Cell, 23(9), 3353-3373. doi:10.1105/tpc.111.087742Leyva, M. O., Vicedo, B., Finiti, I., Flors, V., Del Amo, G., Real, M. D., … González-Bosch, C. (2008). Preventive and post-infection control ofBotrytis cinereain tomato plants by hexanoic acid. Plant Pathology, 57(6), 1038-1046. doi:10.1111/j.1365-3059.2008.01891.xLi, J., Brader, G., Kariola, T., & Tapio Palva, E. (2006). WRKY70 modulates the selection of signaling pathways in plant defense. The Plant Journal, 46(3), 477-491. doi:10.1111/j.1365-313x.2006.02712.xManacorda, C. A., Mansilla, C., Debat, H. J., Zavallo, D., Sánchez, F., Ponz, F., & Asurmendi, S. (2013). Salicylic Acid Determines Differential Senescence Produced by Two Turnip mosaic virus Strains Involving Reactive Oxygen Species and Early Transcriptomic Changes. Molecular Plant-Microbe Interactions®, 26(12), 1486-1498. doi:10.1094/mpmi-07-13-0190-rMandadi, K. K., & Scholthof, K.-B. G. (2013). Plant Immune Responses Against Viruses: How Does a Virus Cause Disease? The Plant Cell, 25(5), 1489-1505. doi:10.1105/tpc.113.111658Mauch-Mani, B., & Mauch, F. (2005). The role of abscisic acid in plant–pathogen interactions. Current Opinion in Plant Biology, 8(4), 409-414. doi:10.1016/j.pbi.2005.05.015Mayers, C. N., Lee, K.-C., Moore, C. A., Wong, S.-M., & Carr, J. P. (2005). Salicylic Acid-Induced Resistance to Cucumber mosaic virus in Squash and Arabidopsis thaliana: Contrasting Mechanisms of Induction and Antiviral Action. Molecular Plant-Microbe Interactions®, 18(5), 428-434. doi:10.1094/mpmi-18-0428Mittler, R. (2017). ROS Are Good. Trends in Plant Science, 22(1), 11-19. doi:10.1016/j.tplants.2016.08.002Miura, K., & Tada, Y. (2014). Regulation of water, salinity, and cold stress responses by salicylic acid. Frontiers in Plant Science, 5. doi:10.3389/fpls.2014.00004Naumann, M., Somerville, S. C., & Voigt, C. A. (2013). Differences in early callose deposition during adapted and non-adapted powdery mildew infection of resistantArabidopsislines. Plant Signaling & Behavior, 8(6), e24408. doi:10.4161/psb.24408Navarro, J. A., Genovés, A., Climent, J., Saurí, A., Martínez-Gil, L., Mingarro, I., & Pallás, V. (2006). RNA-binding properties and membrane insertion of Melon necrotic spot virus (MNSV) double gene block movement proteins. Virology, 356(1-2), 57-67. doi:10.1016/j.virol.2006.07.040Nicaise, V. (2014). Crop immunity against viruses: outcomes and future challenges. Frontiers in Plant Science, 5. doi:10.3389/fpls.2014.00660Nieto, C., Morales, M., Orjeda, G., Clepet, C., Monfort, A., Sturbois, B., … Bendahmane, A. (2006). AneIF4Eallele confers resistance to an uncapped and non-polyadenylated RNA virus in melon. The Plant Journal, 48(3), 452-462. doi:10.1111/j.1365-313x.2006.02885.xNováková, S., Flores-Ramírez, G., Glasa, M., Danchenko, M., Fiala, R., & Skultety, L. (2015). Partially resistant Cucurbita pepo showed late onset of the Zucchini yellow mosaic virus infection due to rapid activation of defense mechanisms as compared to susceptible cultivar. Frontiers in Plant Science, 6. doi:10.3389/fpls.2015.00263Ohki, T., Akita, F., Mochizuki, T., Kanda, A., Sasaya, T., & Tsuda, S. (2010). The protruding domain of the coat protein of Melon necrotic spot virus is involved in compatibility with and transmission by the fungal vector Olpidium bornovanus. Virology, 402(1), 129-134. doi:10.1016/j.virol.2010.03.020Pacheco, R., García-Marcos, A., Manzano, A., de Lacoba, M. G., Camañes, G., García-Agustín, P., … Tenllado, F. (2012). Comparative Analysis of Transcriptomic and Hormonal Responses to Compatible and Incompatible Plant-Virus Interactions that Lead to Cell Death. Molecular Plant-Microbe Interactions®, 25(5), 709-723. doi:10.1094/mpmi-11-11-0305Padmanabhan, M. S., Shiferaw, H., & Culver, J. N. (2006). The Tobacco mosaic virus Replicase Protein Disrupts the Localization and Function of Interacting Aux/IAA Proteins. Molecular Plant-Microbe Interactions®, 19(8), 864-873. doi:10.1094/mpmi-19-0864Pallas, V., & García, J. A. (2011). How do plant viruses induce disease? Interactions and interference with host components. Journal of General Virology, 92(12), 2691-2705. doi:10.1099/vir.0.034603-0Park, S.-W., Li, W., Viehhauser, A., He, B., Kim, S., Nilsson, A. K., … Lawrence, C. B. (2013). Cyclophilin 20-3 relays a 12-oxo-phytodienoic acid signal during stress responsive regulation of cellular redox homeostasis. Proceedings of the National Academy of Sciences, 110(23), 9559-9564. doi:10.1073/pnas.1218872110Peng, H., Li, S., Wang, L., Li, Y., Li, Y., Zhang, C., & Hou, X. (2013). Turnip mosaic virus induces expression of the LRR II subfamily genes and regulates the salicylic acid signaling pathway in non-heading Chinese cabbage. Physiological and Molecular Plant Pathology, 82, 64-72. doi:10.1016/j.pmpp.2013.01.006Rodrigo, G., Carrera, J., Ruiz-Ferrer, V., del Toro, F. J., Llave, C., Voinnet, O., & Elena, S. F. (2012). A Meta-Analysis Reveals the Commonalities and Differences in Arabidopsis thaliana Response to Different Viral Pathogens. PLoS ONE, 7(7), e40526. doi:10.1371/journal.pone.0040526Rodriguez, M. C., Conti, G., Zavallo, D., Manacorda, C. A., & Asurmendi, S. (2014). TMV-Cg Coat Protein stabilizes DELLA proteins and in turn negatively modulates salicylic acid-mediated defense pathway during Arabidopsis thalianaviral infection. BMC Plant Biology, 14(1). doi:10.1186/s12870-014-0210-xScalschi, L., Sanmartín, M., Camañes, G., Troncho, P., Sánchez-Serrano, J. J., García-Agustín, P., & Vicedo, B. (2014). Silencing ofOPR3in tomato reveals the role of OPDA in callose deposition during the activation of defense responses againstBotrytis cinerea. The Plant Journal, 81(2), 304-315. doi:10.1111/tpj.12728Scalschi, L., Vicedo, B., Camañes, G., Fernandez-Crespo, E., Lapeña, L., González-Bosch, C., & García-Agustín, P. (2012). Hexanoic acid is a resistance inducer that protects tomato plants againstPseudomonas syringaeby priming the jasmonic acid and salicylic acid pathways. Molecular Plant Pathology, 14(4), 342-355. doi:10.1111/mpp.12010Serra-Soriano, M., Pallás, V., & Navarro, J. A. (2014). A model for transport of a viral membrane protein through the early secretory pathway: minimal sequence and endoplasmic reticulum lateral mobility requirements. The Plant Journal, 77(6), 863-879. doi:10.1111/tpj.12435Taheri, P., & Tarighi, S. (2010). Riboflavin induces resistance in rice against Rhizoctonia solani via jasmonate-mediated priming of phenylpropanoid pathway. Journal of Plant Physiology, 167(3), 201-208. doi:10.1016/j.jplph.2009.08.003Taheri, P., & Tarighi, S. (2011). A survey on basal resistance and riboflavin-induced defense responses of sugar beet against Rhizoctonia solani. Journal of Plant Physiology, 168(10), 1114-1122. doi:10.1016/j.jplph.2011.01.001Tamogami, S., Noge, K., Abe, M., Agrawal, G. K., & Rakwal, R. (2012). Methyl jasmonate is transported to distal leaves via vascular process metabolizing itself into JA-Ile and triggering VOCs emission as defensive metabolites. Plant Signaling & Behavior, 7(11), 1378-1381. doi:10.4161/psb.21762Ueki, S., & Citovsky, V. (2002). The systemic movement of a tobamovirus is inhibited by a cadmium-ion-induced glycine-rich protein. Nature Cell Biology, 4(7), 478-486. doi:10.1038/ncb806Vatén, A., Dettmer, J., Wu, S., Stierhof, Y.-D., Miyashima, S., Yadav, S. R., … Helariutta, Y. (2011). Callose Biosynthesis Regulates Symplastic Trafficking during Root Development. Developmental Cell, 21(6), 1144-1155. doi:10.1016/j.devcel.2011.10.006Vicedo, B., Flors, V., de la O Leyva, M., Finiti, I., Kravchuk, Z., Real, M. D., … González-Bosch, C. (2009). Hexanoic Acid-Induced Resistance Against Botrytis cinerea in Tomato Plants. Molecular Plant-Microbe Interactions®, 22(11), 1455-1465. doi:10.1094/mpmi-22-11-1455Vlot, A. C., Dempsey, D. A., & Klessig, D. F. (2009). Salicylic Acid, a Multifaceted Hormone to Combat Disease. Annual Review of Phytopathology, 47(1), 177-206. doi:10.1146/annurev.phyto.050908.135202Wang, X., Sager, R., Cui, W., Zhang, C., Lu, H., & Lee, J.-Y. (2013). 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Ectopic callose deposition into woody biomass modulates the nano-architecture of macrofibrils

Plant biomass plays an increasingly important role in the circular bioeconomy, replacing non-renewable fossil resources. Genetic engineering of this lignocellulosic biomass could benefit biorefinery transformation chains by lowering economic and technological barriers to industrial processing. However, previous efforts have mostly targeted the major constituents of woody biomass: cellulose, hemicellulose and lignin. Here we report the engineering of wood structure through the introduction of callose, a polysaccharide novel to most secondary cell walls. Our multiscale analysis of genetically engineered poplar trees shows that callose deposition modulates cell wall porosity, water and lignin contents and increases the lignin-cellulose distance, ultimately resulting in substantially decreased biomass recalcitrance. We provide a model of the wood cell wall nano-architecture engineered to accommodate the hydrated callose inclusions. Ectopic polymer introduction into biomass manifests in new physico-chemical properties and offers new avenues when considering lignocellulose engineering.Bourdon et al. demonstrate the possibility to ectopically synthesize callose, a polymer restricted to primary cell walls, into Arabidopsis and aspen secondary cell walls to manipulate their ultrastructure and ultimately reduce their recalcitrance

A new vesicle trafficking regulator CTL1 plays a crucial role in ion homeostasis

Ion homeostasis is essential for plant growth and environmental adaptation, and maintaining ion homeostasis requires the precise regulation of various ion transporters, as well as correct root patterning. However, the mechanisms underlying these processes remain largely elusive. Here, we reported that a choline transporter gene, CTL1, controls ionome homeostasis by regulating the secretory trafficking of proteins required for plasmodesmata (PD) development, as well as the transport of some ion transporters. Map-based cloning studies revealed that CTL1 mutations alter the ion profile of Arabidopsis thaliana. We found that the phenotypes associated with these mutations are caused by a combination of PD defects and ion transporter misregulation. We also established that CTL1 is involved in regulating vesicle trafficking and is thus required for the trafficking of proteins essential for ion transport and PD development. Characterizing choline transporter-like 1 (CTL1) as a new regulator of protein sorting may enable researchers to understand not only ion homeostasis in plants but also vesicle trafficking in general

Cost-effectiveness of a stepped-care intervention to prevent major depression in patients with type 2 diabetes mellitus and/or coronary heart disease and subthreshold depression: design of a cluster-randomized controlled trial

Background: Co-morbid major depression is a significant problem among patients with type 2 diabetes mellitus and/or coronary heart disease and this negatively impacts quality of life. Subthreshold depression is the most important risk factor for the development of major depression. Given the highly significant association between depression and adverse health outcomes and the limited capacity for depression treatment in primary care, there is an urgent need for interventions that successfully prevent the transition from subthreshold depression into a major depressive disorder. Nurse led stepped-care is a promising way to accomplish this. The aim of this study is to evaluate the cost-effectiveness of a nurse-led indicated stepped-care program to prevent major depression among patients with type 2 diabetes mellitus and/or coronary heart disease in primary care who also have subthreshold depressive symptoms.Methods/design: An economic evaluation will be conducted alongside a cluster-randomized controlled trial in approximately thirty general practices in the Netherlands. Randomization takes place at the level of participating practice nurses. We aim to include 236 participants who will either receive a nurse-led indicated stepped-care program for depressive symptoms or care as usual. The stepped-care program consists of four sequential but flexible treatment steps: 1) watchful waiting, 2) guided self-help treatment, 3) problem solving treatment and 4) referral to the general practitioner. The primary clinical outcome measure is the cumulative incidence of major depressive disorder as measured with the Mini International Neuropsychiatric Interview. Secondary outcomes include severity of depressive symptoms, quality of life, anxiety and physical outcomes. Costs will be measured from a societal perspective and include health care utilization, medication and lost productivity costs. Measurements will be performed at baseline and 3, 6, 9 and 12 months.Discussion: The intervention being investigated is expected to prevent new cases of depression among people with type 2 diabetes mellitus and/or coronary heart disease and subthreshold depression, with subsequent beneficial effects on quality of life, clinical outcomes and health care costs. When proven cost-effective, the program provides a viable treatment option in the Dutch primary care system.Trial registration: Dutch Trial Register NTR3715. © 2013 van Dijk et al.; licensee BioMed Central Ltd

3-aminobenzamide blocks MAMP-induced callose deposition independently of its poly(ADPribosyl)ation inhibiting activity

Cell wall reinforcement with callose is a frequent plant response to infection. Poly(ADP-ribosyl)ation is a protein post-translational modification mediated by poly(ADP-ribose) polymerases (PARPs). Poly(ADP-ribosyl)ation has well-known roles in DNA damage repair and has more recently been shown to contribute to plant immune responses. 3-aminobenzamide (3AB) is an established PARP inhibitor and it blocks the callose deposition elicited by flg22 or elf18, two microbe-associated molecular patterns (MAMPs). However, we report that an Arabidopsis parp1parp2parp3 triple mutant does not exhibit loss of flg22-induced callose deposition. Additionally, the more specific PARP inhibitors PJ-34 and INH2BP inhibit PARP activity in Arabidopsis but do not block MAMP-induced callose deposition. These data demonstrate off-target activity of 3AB and indicate that 3AB inhibits callose deposition through a mechanism other than poly(ADP-ribosyl)ation. POWDERY MILDEW RESISTANT 4 (PMR4) is the callose synthase responsible for the majority of MAMP- and wound-induced callose deposition in Arabidopsis. 3AB does not block wound-induced callose deposition, and 3AB does not reduce the PMR4 mRNA abundance increase in response to flg22. Levels of PMR4-HA protein increase in response to flg22, and increase even more in flg22 + 3AB despite no callose being produced. The callose synthase inhibitor 2-deoxy-D-glucose does not cause similar impacts on PMR4-HA protein levels. Beyond MAMPs, we find that 3AB also reduces callose deposition induced by powdery mildew (Golovinomyces cichoracearum) and impairs the penetration resistance of a PMR4 overexpression line. 3AB thus reveals pathogenesis-associated pathways that activate callose synthase enzymatic activity distinct from those that elevate PMR4 mRNA and protein abundance

Plant vascular development: from early specification to differentiation.

Vascular tissues in plants are crucial to provide physical support and to transport water, sugars and hormones and other small signalling molecules throughout the plant. Recent genetic and molecular studies have identified interconnections among some of the major signalling networks that regulate plant vascular development. Using Arabidopsis thaliana as a model system, these studies enable the description of vascular development from the earliest tissue specification events during embryogenesis to the differentiation of phloem and xylem tissues. Moreover, we propose a model for how oriented cell divisions give rise to a three-dimensional vascular bundle within the root meristem