Challenge MICROTRANSAT

L'IUT de Nantes et l'ENSICA de Toulouse développent conjointement un voilier autonome. Ce projet pédagogique collaboratif a permis de concevoir, fabriquer et d'instrumenter un voilier de 2,4m. Notre démonstrateur a pour but de démontrer la possibilité de faire réaliser une traversée transatlantique à un petit voilier autonome. Nous lançons par cet article le challenge "Microtransat" afin de susciter des projets similaires dans d’autres écoles ou universités

High-throughput colorimetric method for the parallel assay of glyoxylic acid and ammonium in a single extract

Bräutigam A, Gagneul D, Weber APM. High-throughput colorimetric method for the parallel assay of glyoxylic acid and ammonium in a single extract. Analytical Biochemistry. 2007;362(1):151-153

An mRNA Blueprint for C-4 Photosynthesis Derived from Comparative Transcriptomics of Closely Related C-3 and C-4 Species

Bräutigam A, Kajala K, Wullenweber J, et al. An mRNA Blueprint for C-4 Photosynthesis Derived from Comparative Transcriptomics of Closely Related C-3 and C-4 Species. Plant Physiology. 2011;155(1):142-156.C-4 photosynthesis involves alterations to the biochemistry, cell biology, and development of leaves. Together, these modifications increase the efficiency of photosynthesis, and despite the apparent complexity of the pathway, it has evolved at least 45 times independently within the angiosperms. To provide insight into the extent to which gene expression is altered between C-3 and C-4 leaves, and to identify candidates associated with the C-4 pathway, we used massively parallel mRNA sequencing of closely related C-3 (Cleome spinosa) and C-4 (Cleome gynandra) species. Gene annotation was facilitated by the phylogenetic proximity of Cleome and Arabidopsis (Arabidopsis thaliana). Up to 603 transcripts differ in abundance between these C-3 and C-4 leaves. These include 17 transcription factors, putative transport proteins, as well as genes that in Arabidopsis are implicated in chloroplast movement and expansion, plasmodesmatal connectivity, and cell wall modification. These are all characteristics known to alter in a C-4 leaf but that previously had remained undefined at the molecular level. We also document large shifts in overall transcription profiles for selected functional classes. Our approach defines the extent to which transcript abundance in these C-3 and C-4 leaves differs, provides a blueprint for the NAD-malic enzyme C-4 pathway operating in a dicotyledon, and furthermore identifies potential regulators. We anticipate that comparative transcriptomics of closely related species will provide deep insight into the evolution of other complex traits

Arabidopsis A BOUT DE SOUFFLE is a putative mitochondrial transporter involved in photorespiratory metabolism and is required for meristem growth at ambient CO2 levels

Photorespiratory metabolism is essential in all oxygenic photosynthetic organisms. In plants, it is a highly compartmentalized pathway that involves chloroplasts, peroxisomes, mitochondria and the cytoplasm. The metabolic pathway itself is well characterized, and the enzymes required for its function have been identified. However, very little information is available on the transport proteins that catalyze the high metabolic flux between the involved compartments. Here we show that the A BOUT DE SOUFFLE (BOU) gene, which encodes a mitochondrial carrier, is involved in photorespiration in Arabidopsis. BOU was found to be co-expressed with photorespiratory genes in leaf tissues. The knockout mutant bou-2 showed the hallmarks of a photorespiratory growth phenotype, an elevated CO2 compensation point, and excessive accumulation of glycine. Furthermore, degradation of the P-protein, a subunit of glycine decarboxylase, was demonstrated for bou-2, and is reflected in strongly reduced glycine decarboxylase activity. The photorespiration defect in bou-2 has dramatic consequences early in the seedling stage, which are highlighted by transcriptome studies. In bou-2 seedlings, as in shm1, another photorespiratory mutant, the shoot apical meristem organization is severely compromised. Cell divisions are arrested, leading to growth arrest at ambient CO2. Although the specific substrate for the BOU transporter protein remains elusive, we show that it is essential for the function of the photorespiratory metabolism. We hypothesize that BOU function is linked with glycine decarboxylase activity, and is required for normal apical meristems functioning in seedlings

Stress tolerance mechanisms in Juncus: responses to salinity and drought in three Juncus species adapted to different natural environments

[EN] Comparative studies on the responses to salinity and drought were carried out in three Juncus species, two halophytes (Juncus maritimus Lam. and Juncus acutus L.) and one more salt-sensitive (Juncus articulatus L.). Salt tolerance in Juncus depends on the inhibition of transport of toxic ions to the aerial part. In the three taxa studied Na+ and Cl accumulated to the same extent in the roots of salt treated plants; however, ion contents were lower in the shoots and correlated with the relative salt sensitivity of the species, with the lowest levels measured in the halophytes. Activation of K+ transport at high salt concentration could also contribute to salt tolerance in the halophytes. Maintenance of cellular osmotic balance is mostly based on the accumulation of sucrose in the three species. Yet, neither the relative salt-induced increase in sugar content nor the absolute concentrations reached can explain the observed differences in salt tolerance. In contrast, proline increased significantly in the presence of salt only in the salt-tolerant J. maritimus and J. acutus, but not in J. articulatus. Similar patterns of osmolyte accumulation were observed in response to water stress, supporting a functional role of proline in stress tolerance mechanisms in JuncusThis work was partly funded by a grant to O.V. from the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution by the European Regional Development Fund. Mohamad Al Hassan was a recipient of an Erasmus Mundus pre-doctoral scholarship financed by the European Commission (Welcome Consortium)Al Hassan, M.; López Gresa, MP.; Boscaiu Neagu, MT.; Vicente Meana, Ó. (2016). Stress tolerance mechanisms in Juncus: responses to salinity and drought in three Juncus species adapted to different natural environments. FUNCTIONAL PLANT BIOLOGY. 43:949-960. https://doi.org/10.1071/FP16007S94996043Al Hassan, M., Chaura, J., López-Gresa, M. 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American Journal of Botany, 92(7), 1094-1101. doi:10.3732/ajb.92.7.1094Espinar, J. L., García, L. V., Figuerola, J., Green, A. J., & Clemente, L. (2006). Effects of salinity and ingestion by ducks on germination patterns of Juncus subulatus seeds. Journal of Arid Environments, 66(2), 376-383. doi:10.1016/j.jaridenv.2005.11.001Fita, A., Rodríguez-Burruezo, A., Boscaiu, M., Prohens, J., & Vicente, O. (2015). Breeding and Domesticating Crops Adapted to Drought and Salinity: A New Paradigm for Increasing Food Production. Frontiers in Plant Science, 6. doi:10.3389/fpls.2015.00978Flowers, T. J., & Colmer, T. D. (2008). Salinity tolerance in halophytes*. New Phytologist, 179(4), 945-963. doi:10.1111/j.1469-8137.2008.02531.xFlowers, T. J., Hajibagheri, M. A., & Clipson, N. J. W. (1986). Halophytes. The Quarterly Review of Biology, 61(3), 313-337. doi:10.1086/415032Flowers, T. J., Munns, R., & Colmer, T. D. (2014). Sodium chloride toxicity and the cellular basis of salt tolerance in halophytes. Annals of Botany, 115(3), 419-431. doi:10.1093/aob/mcu217Gagneul, D., Aïnouche, A., Duhazé, C., Lugan, R., Larher, F. R., & Bouchereau, A. (2007). A Reassessment of the Function of the So-Called Compatible Solutes in the Halophytic Plumbaginaceae Limonium latifolium. Plant Physiology, 144(3), 1598-1611. doi:10.1104/pp.107.099820GIL, R., LULL, C., BOSCAIU, M., BAUTISTA, I., LIDÓN, A., & VICENTE, O. (2011). Soluble Carbohydrates as Osmolytes in Several Halophytes from a Mediterranean Salt Marsh. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 39(2), 09. doi:10.15835/nbha3927176Gil, R., Boscaiu, M., Lull, C., Bautista, I., Lidón, A., & Vicente, O. (2013). Are soluble carbohydrates ecologically relevant for salt tolerance in halophytes? Functional Plant Biology, 40(9), 805. doi:10.1071/fp12359Gil, R., Bautista, I., Boscaiu, M., Lidon, A., Wankhade, S., Sanchez, H., … Vicente, O. (2014). Responses of five Mediterranean halophytes to seasonal changes in environmental conditions. AoB PLANTS, 6(0), plu049-plu049. doi:10.1093/aobpla/plu049Glenn, E. (1999). Salt Tolerance and Crop Potential of Halophytes. Critical Reviews in Plant Sciences, 18(2), 227-255. doi:10.1016/s0735-2689(99)00388-3GORHAM, J., HUGHES, L., & WYN JONES, R. G. (2006). Chemical composition of salt-marsh plants from Ynys Môn (Anglesey): the concept of physiotypes. Plant, Cell & Environment, 3(5), 309-318. doi:10.1111/1365-3040.ep11581858Grieve, C. M., & Grattan, S. R. (1983). Rapid assay for determination of water soluble quaternary ammonium compounds. Plant and Soil, 70(2), 303-307. doi:10.1007/bf02374789Gupta, B., & Huang, B. (2014). Mechanism of Salinity Tolerance in Plants: Physiological, Biochemical, and Molecular Characterization. International Journal of Genomics, 2014, 1-18. doi:10.1155/2014/701596Hamamoto, S., Horie, T., Hauser, F., Deinlein, U., Schroeder, J. I., & Uozumi, N. (2015). HKT transporters mediate salt stress resistance in plants: from structure and function to the field. Current Opinion in Biotechnology, 32, 113-120. doi:10.1016/j.copbio.2014.11.025Hariadi, Y., Marandon, K., Tian, Y., Jacobsen, S.-E., & Shabala, S. (2010). Ionic and osmotic relations in quinoa (Chenopodium quinoa Willd.) plants grown at various salinity levels. Journal of Experimental Botany, 62(1), 185-193. doi:10.1093/jxb/erq257Jones, E., Simpson, D., Hodkinson, T., Chase, M., & Parnell, J. (2007). The Juncaceae-Cyperaceae Interface: A Combined Plastid Sequence Analysis. Aliso, 23(1), 55-61. doi:10.5642/aliso.20072301.07Kumari, A., Das, P., Parida, A. K., & Agarwal, P. K. (2015). Proteomics, metabolomics, and ionomics perspectives of salinity tolerance in halophytes. Frontiers in Plant Science, 6. doi:10.3389/fpls.2015.00537Munns, R., & Termaat, A. (1986). Whole-Plant Responses to Salinity. Functional Plant Biology, 13(1), 143. doi:10.1071/pp9860143Munns, R., & Tester, M. (2008). Mechanisms of Salinity Tolerance. Annual Review of Plant Biology, 59(1), 651-681. doi:10.1146/annurev.arplant.59.032607.092911Naidoo, G., & Kift, J. (2006). Responses of the saltmarsh rush Juncus kraussii to salinity and waterlogging. Aquatic Botany, 84(3), 217-225. doi:10.1016/j.aquabot.2005.10.002Niu, X., Bressan, R. A., Hasegawa, P. M., & Pardo, J. M. (1995). Ion Homeostasis in NaCl Stress Environments. Plant Physiology, 109(3), 735-742. doi:10.1104/pp.109.3.735Ozgur, R., Uzilday, B., Sekmen, A. H., & Turkan, I. (2013). Reactive oxygen species regulation and antioxidant defence in halophytes. Functional Plant Biology, 40(9), 832. doi:10.1071/fp12389Pang, Q., Chen, S., Dai, S., Chen, Y., Wang, Y., & Yan, X. (2010). Comparative Proteomics of Salt Tolerance inArabidopsis thalianaandThellungiella halophila. Journal of Proteome Research, 9(5), 2584-2599. doi:10.1021/pr100034fPartridge, T. R., & Wilson, J. B. (1987). Salt tolerance of salt marsh plants of Otago, New Zealand. New Zealand Journal of Botany, 25(4), 559-566. doi:10.1080/0028825x.1987.10410086RAVEN, J. A. (1985). TANSLEY REVIEW No. 2. REGULATION OF PH AND GENERATION OF OSMOLARITY IN VASCULAR PLANTS: A COST-BENEFIT ANALYSIS IN RELATION TO EFFICIENCY OF USE OF ENERGY, NITROGEN AND WATER. New Phytologist, 101(1), 25-77. doi:10.1111/j.1469-8137.1985.tb02816.xRodrı́guez-Navarro, A. (2000). Potassium transport in fungi and plants. Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes, 1469(1), 1-30. doi:10.1016/s0304-4157(99)00013-1Rozema, J. (1976). An Ecophysiological Study on the Response to Salt of Four Halophytic and Glycophytic Juncus Species. Flora, 165(2), 197-209. doi:10.1016/s0367-2530(17)31845-5Rozema, J. (1991). Growth, water and ion relationships of halophytic monocotyledonae and dicotyledonae; a unified concept. Aquatic Botany, 39(1-2), 17-33. doi:10.1016/0304-3770(91)90019-2Smirnoff, N., & Cumbes, Q. J. (1989). Hydroxyl radical scavenging activity of compatible solutes. 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Metabolic responses to salt stress of barley (Hordeum vulgare L.) cultivars, Sahara and Clipper, which differ in salinity tolerance

Plants show varied cellular responses to salinity that are partly associated with maintaining low cytosolic Na+ levels and a high K+/Na+ ratio. Plant metabolites change with elevated Na+, some changes are likely to help restore osmotic balance while others protect Na+-sensitive proteins. Metabolic responses to salt stress are described for two barley (Hordeum vulgare L.) cultivars, Sahara and Clipper, which differed in salinity tolerance under the experimental conditions used. After 3 weeks of salt treatment, Clipper ceased growing whereas Sahara resumed growth similar to the control plants. Compared with Clipper, Sahara had significantly higher leaf Na+ levels and less leaf necrosis, suggesting they are more tolerant to accumulated Na+. Metabolite changes in response to the salt treatment also differed between the two cultivars. Clipper plants had elevated levels of amino acids, including proline and GABA, and the polyamine putrescine, consistent with earlier suggestions that such accumulation may be correlated with slower growth and/or leaf necrosis rather than being an adaptive response to salinity. It is suggested that these metabolites may be an indicator of general cellular damage in plants. By contrast, in the more tolerant Sahara plants, the levels of the hexose phosphates, TCA cycle intermediates, and metabolites involved in cellular protection increased in response to salt. These solutes remain unchanged in the more sensitive Clipper plants. It is proposed that these responses in the more tolerant Sahara are involved in cellular protection in the leaves and are involved in the tolerance of Sahara leaves to high Na+

Effects of salinity and ascorbic acid on growth, water status and antioxidant system in a perennial halophyte

Salinity causes oxidative stress in plants by enhancing production of reactive oxygen species, so that an efficient antioxidant system, of which ascorbic acid (AsA) is a key component, is an essential requirement of tolerance. However, antioxidant responses of plants to salinity vary considerably among species. Limonium stocksii is a sub-tropical halophyte found in the coastal marshes from Gujarat (India) to Karachi (Pakistan) but little information exists on its salt resistance. In order to investigate the role of AsA in tolerance, 2-month-old plants were treated with 0 (control), 300 (moderate) and 600 (high) mM NaCl for 30 days with or without exogenous application of AsA (20 mM) or distilled water. Shoot growth of unsprayed plants at moderate salinity was similar to that of controls while at high salinity growth was inhibited substantially. Sap osmolality, AsA concentrations and activities of AsA-dependant antioxidant enzymes increased with increasing salinity. Water spray resulted in some improvement in growth, indicating that the growth promotion by exogenous treatments could partly be attributed to water. However, exogenous application of AsA on plants grown under saline conditions improved growth and AsA dependent antioxidant enzymes more than the water control treatment. Our data show that AsA-dependent antioxidant enzymes play an important role in salinity tolerance of L. stocksii.Higher Education Commission of Pakistan for provision of funds under a research grant entitled ‘Salt-induced Oxidative Stress: Consequences and Possible Management’

Gene Transfer from Bacteria and Archaea Facilitated Evolution of an Extremophilic Eukaryote

Schoenknecht G, Chen W-H, Ternes CM, et al. Gene Transfer from Bacteria and Archaea Facilitated Evolution of an Extremophilic Eukaryote. Science. 2013;339(6124):1207-1210.Some microbial eukaryotes, such as the extremophilic red alga Galdieria sulphuraria, live in hot, toxic metal-rich, acidic environments. To elucidate the underlying molecular mechanisms of adaptation, we sequenced the 13.7-megabase genome of G. sulphuraria. This alga shows an enormous metabolic flexibility, growing either photoautotrophically or heterotrophically on more than 50 carbon sources. Environmental adaptation seems to have been facilitated by horizontal gene transfer from various bacteria and archaea, often followed by gene family expansion. At least 5% of protein-coding genes of G. sulphuraria were probably acquired horizontally. These proteins are involved in ecologically important processes ranging from heavy-metal detoxification to glycerol uptake and metabolism. Thus, our findings show that a pan-domain gene pool has facilitated environmental adaptation in this unicellular eukaryote

Effects of Salt Stress on Three Ecologically Distinct Plantago Species

Comparative studies on the responses to salt stress of taxonomically related taxa should help to elucidate relevant mechanisms of stress tolerance in plants. We have applied this strategy to three Plantago species adapted to different natural habitats, P. crassifolia and P. coronopus both halophytes and P. major, considered as salt-sensitive since it is never found in natural saline habitats. Growth inhibition measurements in controlled salt treatments indicated, however, that P. major is quite resistant to salt stress, although less than its halophytic congeners. The contents of monovalent ions and specific osmolytes were determined in plant leaves after four-week salt treatments. Salt-treated plants of the three taxa accumulated Na+ and Cl- in response to increasing external NaCl concentrations, to a lesser extent in P. major than in the halophytes; the latter species also showed higher ion contents in the non-stressed plants. In the halophytes, K+ concentration decreased at moderate salinity levels, to increase again under high salt conditions, whereas in P. major K+ contents were reduced only above 400 mM NaCl. Sorbitol contents augmented in all plants, roughly in parallel with increasing salinity, but the relative increments and the absolute values reached did not differ much in the three taxa. On the contrary, a strong (relative) accumulation of proline in response to high salt concentrations (600 800 mM NaCl) was observed in the halophytes, but not in P. major. These results indicate that the responses to salt stress triggered specifically in the halophytes, and therefore the most relevant for tolerance in the genus Plantago are: a higher efficiency in the transport of toxic ions to the leaves, the capacity to use inorganic ions as osmotica, even under low salinity conditions, and the activation, in response to very high salt concentrations, of proline accumulation and K+ transport to the leaves of the plants.MAH was a recipient of an Erasmus Mundus pre-doctoral scholarship financed by the European Commission (Welcome Consortium). AP acknowledges the Erasmus mobility programme for funding her stay in Valencia to carry out her Master Thesis.Al Hassan, M.; Pacurar, AM.; López Gresa, MP.; Donat Torres, MDP.; Llinares Palacios, JV.; Boscaiu Neagu, MT.; Vicente Meana, Ó. (2016). Effects of Salt Stress on Three Ecologically Distinct Plantago Species. PLoS ONE. 11(8):1-21. doi:10.1371/journal.pone.0160236S12111