Leaf-applied sodium chloride promotes cadmium accumulation in durum wheat grain

Cadmium (Cd) accumulation in durum wheat grain is a growing concern. Among the factors affecting Cd accumulation in plants, soil chloride (Cl) concentration plays a critical role. The effect of leaf NaCl application on grain Cd was studied in greenhouse-grown durum wheat (Triticum turgidum L. durum, cv. Balcali-2000) by immersing (10 s) intact flag leaves into Cd and/or NaCl-containing solutions for 14 times during heading and dough stages. Immersing flag leaves in solutions containing increasing amount of Cd resulted in substantial increases in grain Cd concentration. Adding NaCl alone or in combination with the Cd-containing immersion solution promoted accumulation of Cd in the grains, by up to 41%. In contrast, Zn concentrations of grains were not affected or even decreased by the NaCl treatments. This is likely due to the effect of Cl complexing Cd and reducing positive charge on the metal ion, an effect that is much smaller for Zn. Charge reduction or removal (CdCl2 0 species) would increase the diffusivity/lipophilicity of Cd and enhance its capability to penetrate the leaf epidermis and across membranes. Of even more significance to human health was the ability of Cl alone to penetrate leaf tissue and mobilize and enhance shoot Cd transfer to grains, yet reducing or not affecting Zn transfer

Barley sodium content is regulated by natural variants of the Na+ transporter HvHKT1;5

During plant growth, sodium (Na+) in the soil is transported via the xylem from the root to the shoot. While excess Na+ is toxic to most plants, non-toxic concentrations have been shown to improve crop yields under certain conditions, such as when soil K+ is low. We quantified grain Na+ across a barley genome-wide association study panel grown under non-saline conditions and identified variants of a Class 1 HIGH-AFFINITY-POTASSIUM-TRANSPORTER (HvHKT1;5)-encoding gene responsible for Na+ content variation under these conditions. A leucine to proline substitution at position 189 (L189P) in HvHKT1;5 disturbs its characteristic plasma membrane localisation and disrupts Na+ transport. Under low and moderate soil Na+, genotypes containing HvHKT1:5P189 accumulate high concentrations of Na+ but exhibit no evidence of toxicity. As the frequency of HvHKT1:5P189 increases significantly in cultivated European germplasm, we cautiously speculate that this non-functional variant may enhance yield potential in non-saline environments, possibly by offsetting limitations of low available K+

Metabolomics demonstrates divergent responses of two Eucalyptus species to water stress

Past studies of water stress in Eucalyptus spp. generally highlighted the role of fewer than five “important” metabolites, whereas recent metabolomic studies on other genera have shown tens of compounds are affected. There are currently no metabolite profiling data for responses of stress-tolerant species to water stress. We used GC–MS metabolite profiling to examine the response of leaf metabolites to a long (2 month) and severe (Ψpredawn < −2 MPa) water stress in two species of the perennial tree genus Eucalyptus (the mesic Eucalyptus pauciflora and the semi-arid Eucalyptus dumosa). Polar metabolites in leaves were analysed by GC–MS and inorganic ions by capillary electrophoresis. Pressure–volume curves and metabolite measurements showed that water stress led to more negative osmotic potential and increased total osmotically active solutes in leaves of both species. Water stress affected around 30–40% of measured metabolites in E. dumosa and 10–15% in E. pauciflora. There were many metabolites that were affected in E. dumosa but not E. pauciflora, and some that had opposite responses in the two species. For example, in E. dumosa there were increases in five acyclic sugar alcohols and four low-abundance carbohydrates that were unaffected by water stress in E. pauciflora. Re-watering increased osmotic potential and decreased total osmotically active solutes in E. pauciflora, whereas in E. dumosa re-watering led to further decreases in osmotic potential and increases in total osmotically active solutes. This experiment has added several extra dimensions to previous targeted analyses of water stress responses in Eucalyptus, and highlights that even species that are closely related (e.g. congeners) may respond differently to water stress and re-waterin

The sugar beet gene encoding the sodium/proton exchanger 1 (BvNHX1) is regulated by a MYB transcription factor

Sodium/proton exchangers (NHX) are key players in the plant response to salinity and have a central role in establishing ion homeostasis. NHXs can be localized in the tonoplast or plasma membranes, where they exchange sodium ions for protons, resulting in sodium ions being removed from the cytosol into the vacuole or extracellular space. The expression of most plant NHX genes is modulated by exposure of the organisms to salt stress or water stress. We explored the regulation of the vacuolar NHX1 gene from the salt-tolerant sugar beet plant (BvNHX1) using Arabidopsis plants transformed with an array of constructs of BvHNX1::GUS, and the expression patterns were characterized using histological and quantitative assays. The 5′ UTR of BvNHX1, including its intron, does not modulate the activity of the promoter. Serial deletions show that a 337 bp promoter fragment sufficed for driving activity that indistinguishable from that of the full-length (2,464 bp) promoter. Mutating four putative cis-acting elements within the 337 bp promoter fragment revealed that MYB transcription factor(s) are involved in the activation of the expression of BvNHX1 upon exposure to salt and water stresses. Gel mobility shift assay confirmed that the WT but not the mutated MYB binding site is bound by nuclear protein extracted from salt-stressed Betavulgaris leaves

Is salinity the main ecologic factor that shapes the distribution of two endemic Mediterranean plant species of the genus Gypsophila?

The final publication is available at Springer via http://dx.doi.org/10.1007/s11104-014-2218-2Aims Responses to salt stress of two Gypsophila species that share territory, but with different ecological optima and distribution ranges, were analysed. G. struthium is a regionally dominant Iberian endemic gypsophyte, whereas G. tomentosa is a narrow endemic reported as halophyte. Theworking hypothesis is that salt tolerance shapes the presence of these species in their specific habitats. Methods Taking a multidisciplinary approach, we assessed the soil characteristics and vegetation structure at the sampling site, seed germination and seedling development, growth and flowering, synthesis of proline and cation accumulation under artificial conditions of increasing salt stress and effect of PEG on germination and seedling development. Results Soil salinity was low at the all sampling points where the two species grow, but moisture was higher in the area of G. tomentosa. Differences were found in the species salt and drought tolerance. The different parameters tested did not show a clear pattern indicating the main role of salt tolerance in plant distribution. Conclusions G. tomentosa cannot be considered a true halophyte as previously reported because it is unable to complete its life cycle under salinity. The presence of G. tomentosa in habitats bordering salt marshes is a strategy to avoid plant competition and extreme water stressSoriano, P.; Moruno Manchón, JF.; Boscaiu Neagu, MT.; Vicente Meana, Ó.; Hurtado, A.; Llinares Palacios, JV.; Estrelles, E. (2014). Is salinity the main ecologic factor that shapes the distribution of two endemic Mediterranean plant species of the genus Gypsophila?. Plant and Soil. 384(1-2):363-379. doi:10.1007/s11104-014-2218-2S3633793841-2Alonso MA (1996) Flora y vegetación del Valle de Villena (Alicante). Instituto de Cultura Juan Gil-Albert, AlicanteAlvarado JJ, Ruiz JM, López-Cantarero I, Molero J, Romero L (2000) Nitrogen metabolism in five plant species characteristic of gypsiferous soils. Plant Physiol 156:612–616Ashraf M, Foolad MR (2007) Roles of glycine betaine and proline in improving plant abiotic stress resistance. Environ Exp Bot 59:206–216Ashraf MY (2009) Salt tolerance mechanisms in some halophytes from Saudi Arabia and Egypt. Res J Agric Biol Sci 5:191–206Bates LS, Waldren RP, Tear LD (1973) Rapid determination of free proline for water-stress studies. Plant Soil 39:205–207Ben-Gal A, Neori-Borochov H, Yermiyahu U, Shani U (2009) Is osmotic potential a more appropriate property than electrical conductivity for evaluating whole plant response to salinity? Environ Exp Bot 65:232–237Biondi E (2011) Phytosociology today: Methodological and conceptual evolution. Plant Biosyst 145:19–29Boscaiu M, Bautista I, Lidón A, Llinares J, Lull C, Donat P, Mayoral O, Vicente O (2013a) Environmental-dependent proline accumulation in plants living on gypsum soils. Acta Physiol Plant 35:2193–2204Boscaiu M, Llul C, Llinares J, Vicente O, Boira H (2013b) Proline as a biochemical marker in relation to the ecology of two halophytic Juncus species. J Plant Ecol 6:177–186Bradford KJ (1990) A water relations analysis of seed germination rates. Plant Physiol 94:840–849Breckle SW (1999) Halophytic and gypsophytic vegetation of the Ebro-Basin at Los Monegros. In: Melic A, Blasco-Zumeta J (eds) Manifiesto científico por Los Monegros, vol 24, Bol. SEA., pp 101–104Brenchley JL, Probert RJ (1998) Seed germination responses to some environmental factors in the sea grass Zoostera capricorni from eastern Australia. Aquat Bot 62:177–188Cañadas EM, Ballesteros M, Valle F, Lorite J (2013) Does gypsum influence seed germination? Turk J Bot 38:141–147Chen Z, Cuin TA, Zhou M et al (2007) Compatible solute accumulation and stress-mitigating effects in barley genotypes contrasting in their salt tolerance. J Exp Bot 58:4245–4255Chutipaijit S, Cha-Um S, Sompornailin K (2009) Differential accumulation of proline and flavonoids in Indica rice varieties against salinity. Pak J Bot 41:2497–2506Cushman JC (2001) Osmoregulation in plants: implications for agriculture. Am Zool 41:758–769Debussche M, Thompson JD (2003) Habitat differentiation between two closely related Mediterranean plant species, the endemic Cyclamen balearicum and the widespread C. repandum. Acta Oecol 24:35–45Eskandari H, Kazemi K (2011) Germination and seedling properties of different wheat cultivars under salinity conditions. Not Sci Biol 3:130–134FAO (2006) Guidelines for soil descriptions, 5th edn. Food and Agricultural Organization of United Nation, RomeFerrandis P, Herranz JM, Copete MA (2005) Caracterización florística y edáfica de las estepas yesosas de Castilla-La Mancha. Invest Agrar Sist Recur For 14:195–216Flowers TJ, Hall JL (1978) Salt tolerance in Suaeda maritima (L.) Dum. The effect of sodium chloride on growth and soluble enzymes in a comparative study with Pisum sativum L. J Exp Bot 23:310–321Flowers TJ, Colmer TD (2008) Salinity tolerance in halophytes. New Phytol 179:945–963Flowers TJ, Hajibagheri MA, Clipson NJW (1986) Halophytes. Q Rev Biol 61:313–335García-Fuentes A, Salazar C, Torres JA, Cano E, Valle F (2001) Review of communities of Lygeum spartum L. in the south-eastern Iberian Peninsula (western Mediterranean). J Arid Environ 48:323–339Géhu JM (2006) Dictionnaire de Sociologie et Synécologie Végétales. J. Cramer, Berlin-Stuttgart, p 899Géhu JM (2011) On the opportunity to celebrate the centenary of modern phytosociology in 2010. Plant Biosyst 145(suppl):4–8Ghassemi F, Jakeman AJ, Nix HA (1995) Salinisation of land and water resources: human causes, extent, management and case studies. Canberra, Australia. CAB International, The Australian National University, WallingfordGrigore MN, Boscaiu M, Vicente O (2011) Assessment of the relevance of osmolyte biosynthesis for salt tolerance of halophytes under natural conditions. Eur J Plant Sci Biotech 5:12–19Grigore MN, Villanueva M, Boscaiu M, Vicente O (2012a) Do halophytes really require salts for their growth and development? An experimental approach mitigation of salt stress-induced inhibition of Plantago crassifolia reproductive development by supplemental calcium or magnesium. Not Sci Biol 4:23–29Grigore MN, Boscaiu M, Llinares J, Vicente O (2012b) Mitigation of salt stressed-induced Inhibition of Plantago crassifolia reproductive development by supplemental calcium or magnesium. Not Bot Horti Agrobo 40:58–66Hare PD, Cress WA (1997) Metabolic implications of stress-induced proline accumulation in plants. Plant Growth Regul 21:79–102Ishikawa SI, Kachi N (2000) Differential salt tolerance of two Artemisia species growing in contrasting coastal habitats. Ecol Res 15:241–247Kebreab E, Murdoch AJ (1999) Modelling the effects of water stress and temperature on germination rate of Orobanche aegyptiaca seeds. J Exp Bot 50:655–664Khan MA (2002) Halophyte seed germination: Success and Pitfalls. In: Hegazi AM, El-Shaer HM, El-Demerdashe S et al (eds) International symposium on optimum resource utilization in salt affected ecosystems in arid and semi arid regions. Desert Research Centre, Cairo, pp 346–358Khan MA, Gul B, Weber DJ (2000) Germination responses of Salicornia rubra to temperature and salinity. J Arid Environ 45:207–214Khan A, Rayner GD (2003) Robustness to non-normality of common tests for the many-sample location problem. J Appl Math Decis Sci 7:187–206Lidón A, Boscaiu M, Collado F, Vicente O (2009) Soil requirements of three salt tolerant, endemic species from south-east Spain. Not Bot Horti Agrobo 37:64–70López González G (1990) Gypsohila L. In: Castroviejo S, Laínz M, López G et al (eds) Flora Ibérica 2. Real Jardín Botánico, Madrid, pp 408–415Lutts S, Kinet JM, Bouharmont J (1996) Effects of salt stress on growth, mineral nutrition and proline accumulation in relation to osmotic adjustment in rice (Oryza sativa L.) cultivars differing in salinity resistance. Plant Growth Regul 19:207–218Madidi S, Baroudi B, Ameur FB (2004) Effects of salinity on germination and early growth of barley (Hordeum vulgare L.) cultivars. Int J Agric Biol 6:767–770Marchal FM, Lendínez ML, Salazar C, Torres JA (2008) Aportaciones al conocimiento de la vegetación gispsícola en el occidente de la provincia de Granada (sur de España). Lazaroa 29:95–100Médail F, Verlaque R (1997) Ecological characteristics and rarity of endemic plants from southern France and Corsica: implications for biodiversity conservation. Biol Conserv 80:269–281Meyer SE (1986) The ecology of gypsophile endemism in the Eastern Mojave desert. Ecology 67:1303–1313Moruno F, Soriano P, Oscar V, Boscaiu M, Estrelles E (2011) Opportunistic germination behaviour of Gypsophila (Caryophyllaceae) in two priority habitats from semi-arid Mediterranean steppes. Not Bot Horti Agrobo 9:18–23Mota JF, Sánchez Gómez P, Merlo Calvente ME, Catalán Rodríguez P, Laguna Lumbreras E, de la Cruz RM, Navarro Reyes FB, Marchal Gallardo F, Bartolomé Esteban C, Martínez Labarga JM, Sainz Ollero H, Valle Tendero F, Serra Laliga L, Martínez Hernández F, Garrido Becerra JA, Pérez García FJ (2009) Aproximación a la checklist de los gipsófitos ibéricos. An Biol 31:71–80Mota JF, Sola AJ, Jiménez-Sánchez ML, Pérez-García F, Merlo ME (2004) Gypsicolous flora, conservation and restoration of quarries in the southeast of the Iberian Peninsula. Biodivers Conserv 13:1797–1808Munns R (2002) Comparative physiology of salt and water stress. Plant Cell Environ 25:239–250Palacio S, Escudero A, Montserrat-Martí G, Maestro M, Milla R, Albert M (2007) Plants living on gypsum: beyond the specialist model. Ann Bot 99:333–343Peinado M, Martínez-Parras JM (1982) Sobre la posición fitosociológica de Gypsophila tomentosa L. Lazaroa 4:129–140Pueyo Y, Alados CL, Maestro M, Komac B (2007) Gypsophile vegetation patterns under a range of soil properties induced by topographical position. Plant Ecol 189:301–311Rasband WS (1997–2012) ImageJ. U S National Institutes of Health. http://rsb.info.nih.gov/ij/ , Bethesda, MarylandRivas-Martínez S (2005) Notions on dynamic-catenal phytosociology as a basis of landscape science. Plant Biosyst 139:135–144Rivas-Martínez S, Rivas-Saenz S (1996–2009) Worldwide bioclimatic classification system, Phytosociological Research Center, Spain. http://www.globalbioclimatics.org . Accessed 1 July 2013Rivas-Martínez S, Fernández-González F, Loidi J, Lousã M, Penas A (2001) Syntaxonomical checklist of vascular plant communities of Spain and Portugal to association level. Itinera Geobot 14:5–341Salmerón-Sánchez E, Martínez-Nieto MI, Martínez-Hernández F, Garrido-Becerra JA, Mendoza-Fernández AJ, Gil de Carrasco C, Ramos-Miras JJ, Lozano R, Merlo ME, Mota JF (2014) Ecology, genetic diversity and phylogeography of the Iberian endemic plant Jurinea pinnata (Lag.) DC. (Compositae) on two special edaphic substrates: dolomite and gypsum. Plant Soil 374:233–250Saradhi P, Alia P, Arora S, Prasad KV (1995) Proline accumulates in plants exposed to UV radiation and protects them against UV induced peroxidation. Biochem Biophys Res Commun 209:1–5Sekmen AH, Turkan I, Tanyolac ZO, Ozfidan C, Dinc A (2012) Different antioxidant defense responses to salt stress during germination and vegetative stages of endemic halophyte Gypsophila oblanceolata Bark. Environ Exp Bot 77:63–76Tipirdamaz R, Gagneul D, Duhaze C, Ainouche A, Monnier C, Ozkum D, Larher F (2006) Clustering of halophytes from an inland salt marsh in Turkey according to their ability to accumulate sodium and nitrogenous osmolytes. Environ Exp Bot 57:139–153Ungar IA (1996) Effect of salinity on seed germination, growth, and ion accumulation of Atriplex patula (Chenopodiaceae). Am J Bot 83:604–607USDA-ARS (2008) Research databases. Bibliography on salt tolerance. George E. Brown, Jr. Salinity Lab. US Dep. Agric., Agric. Res. Serv. Riverside, CA. http://www.ars.usda.gov/Services/docs.htm?docid=8908USSL Staff (1954) Diagnosis and improvement of saline and alkali soils. US Department of Agriculture Handbook no. 60, 160 ppVicente O, Boscaiu M, Naranjo M, Estrelles E, Bellés JM, Soriano P (2004) Responses to salt stress in the halophyte Plantago crassifolia (Plantaginaceae). J Arid Environ 58:463–48

Cross-tolerance to abiotic stresses in halophytes: Application for phytoremediation of organic pollutants

International audienceHalopytes are plants able to tolerate high salt concentrations but no clear definition was retained for them. In literature, there are more studies that showed salt-enhanced tolerance to other abiotic stresses compared to investigations that found enhanced salt tolerance by other abiotic stresses in halophytes. The phenomenon by which a plant resistance to a stress induces resistance to another is referred to as cross-tolerance. In this work, we reviewed cross-tolerance in halophytes at the physiological, biochemical, and molecular levels. A special attention was accorded to the cross-tolerance between salinity and organic pollutants that could allow halophytes a higher potential of xenobiotic phytoremediation in comparison with glycophytes

An insertional mutagenesis programme with an enhancer trap for the identification and tagging of genes involved in abiotic stress tolerance in the tomato wild-related species Solanum pennellii

Salinity and drought have a huge impact on agriculture since there are few areas free of these abiotic stresses and the problem continues to increase. In tomato, the most important horticultural crop worldwide, there are accessions of wild-related species with a high degree of tolerance to salinity and drought. Thus, the finding of insertional mutants with other tolerance levels could lead to the identification and tagging of key genes responsible for abiotic stress tolerance. To this end, we are performing an insertional mutagenesis programme with an enhancer trap in the tomato wild-related species Solanum pennellii. First, we developed an efficient transformation method which has allowed us to generate more than 2,000 T-DNA lines. Next, the collection of S. pennelli T0 lines has been screened in saline or drought conditions and several presumptive mutants have been selected for their salt and drought sensitivity. Moreover, T-DNA lines with expression of the reporter uidA gene in specific organs, such as vascular bundles, trichomes and stomata, which may play key roles in processes related to abiotic stress tolerance, have been identified. Finally, the growth of T-DNA lines in control conditions allowed us the identification of different development mutants. Taking into account that progenies from the lines are being obtained and that the collection of T-DNA lines is going to enlarge progressively due to the high transformation efficiency achieved, there are great possibilities for identifying key genes involved in different tolerance mechanisms to salinity and drought