Sylvain Bourgerie

Insights into Populus XIP aquaporins: evolutionary expansion, protein functionality, and environmental regulation

A novel category of major intrinsic proteins which share weak similarities with previously identified aquaporin subfamilies was recently identified in land plants, and named X (for unrecognized) intrinsic proteins (XIPs). Because XIPs are still ranked as uncharacterized proteins, their further molecular characterization is required. Herein, a systematic fine-scale analysis of XIP sequences found in flowering plant databases revealed that XIPs are found in at least five groups. The phylogenetic relationship of these five groups with the phylogenetic organization of angiosperms revealed an original pattern of evolution for the XIP subfamily through distinct angiosperm taxon-specific clades. Of all flowering plant having XIPs, the genus Populus encompasses the broadest panel and the highest polymorphism of XIP isoforms, with nine PtXIP sequences distributed within three XIP groups. Comprehensive PtXIP gene expression patterns showed that only two isoforms (PtXIP2;1 and PtXIP3;2) were transcribed in vegetative tissues. However, their patterns are contrasted, PtXIP2;1 was ubiquitously accumulated whereas PtXIP3;2 was predominantly detected in wood and to a lesser extent in roots. Furthermore, only PtXIP2;1 exhibited a differential expression in leaves and stems of drought-, salicylic acid-, or wounding-challenged plants. Unexpectedly, the PtXIPs displayed different abilities to alter water transport upon expression in Xenopus laevis oocytes. PtXIP2;1 and PtXIP3;3 transported water while other PtXIPs did not.

The Hevea brasiliensis XIP aquaporin subfamily : genomic, structural and functional characterizations with relevance to intensive latex harvesting

X-Intrinsic Proteins (XIP) were recently identified in a narrow range of plants as a full clade within the aquaporins. These channels reportedly facilitate the transport of a wide range of hydrophobic solutes. The functional roles of XIP in planta remain poorly identified. In this study, we found three XIP genes (HbXIP1;1, HbXIP2;1 and HbXIP3;1) in the Hevea brasiliensis genome. Comprehensive bioinformatics, biochemical and structural analyses were used to acquire a better understanding of this AQP subfamily. Phylogenetic analysis revealed that HbXIPs clustered into two major groups, each distributed in a specific lineage of the order Malpighiales. Tissue-specific expression profiles showed that only HbXIP2;1 was expressed in all the vegetative tissues tested (leaves, stem, bark, xylem and latex), suggesting that HbXIP2;1 could take part in a wide range of cellular processes. This is particularly relevant to the rubber-producing laticiferous system, where this isoform was found to be up-regulated during tapping and ethylene treatments. Furthermore, the XIP transcriptional pattern is significantly correlated to latex production level. Structural comparison with SoPIP2;1 from Spinacia oleracea species provides new insights into the possible role of structural checkpoints by which HbXIP2;1 ensures glycerol transfer across the membrane. From these results, we discuss the physiological involvement of glycerol and HbXIP2;1 in water homeostasis and carbon stream of challenged laticifers. The characterization of HbXIP2;1 during rubber tree tapping lends new insights into molecular and physiological response processes of laticifer metabolism in the context of latex exploitation.

Cd, Pb, and Zn mobility and (bio)availability in contaminated soils from a former smelting site amended with biochar

Biochar is a potential candidate for the remediation of metal(loid)-contaminated soils. However, the mechanisms of contaminant-biochar retention and release depend on the amount of soil contaminants and physicochemical characteristics, as well as the durability of the biochar contaminant complex, which may be related to the pyrolysis process parameters. The objective of the present study was to evaluate, in a former contaminated smelting site, the impact of two doses of wood biochar (2 and 5% w/w) on metal immobilization and/or phytoavailability and their effectiveness in promoting plant growth in mesocosm experiments. Different soil mixtures were investigated. The main physicochemical parameters and the Cd, Pb, and Zn contents were determined in soil and in soil pore water. Additionally, the growth, dry weight, and metal concentrations were analyzed in the different dwarf bean plant (Phaseolus vulgaris L.) organs tested. Results showed that the addition of biochar at two doses (2 and 5%) improved soil conditions by increasing soil pH, electrical conductivity, and water holding capacity. Furthermore, the application of biochar (5%) to metal-contaminated soil reduced Cd, Pb, and Zn mobility and availability, and hence their accumulation in the different P. vulgaris L. organs. In conclusion, the data clearly demonstrated that biochar application can be effectively used for Cd, Pb, and Zn immobilization, thereby reducing their bioavailability and phytotoxicity.

Assisted Phytoremediation of a Multi-contaminated Industrial Soil Using Biochar and Garden Soil Amendments Associated with Salix alba or Salix viminalis: Abilities to Stabilize As, Pb, and Cu

With the development of the industrial era, environmental pollution by organic and inorganic pollutants increased and became a worldwide issue. Particularly, former industrial sites often present high concentrations of metal(loid)s. These pollutions have adverse effects not only on the environment but also to human health, as pollutants can enter the food chain. Therefore, contaminated sites need rehabilitation. Phytoremediation is a clean and low-cost solution to remediate such sites. However, vegetation establishment can be difficult on such extreme soils from both a physical and a chemical point of view. Consequently, amendments, like biochar and garden soil, must be applied. Biochar, product of biomass pyrolysis under low-oxygen conditions, showed beneficial effects on soil fertility and plant growth, as well as metal(loid) sorption properties. The aims of this study were to investigate the effects of two organic amendments, biochar and garden soil, alone or combined, on the physico-chemical properties of a post-industrial soil and the growth of two Salix species (Salix alba and Salix viminalis) and evaluate the phytostabilizing capacities of the two Salix species. In this goal, a greenhouse experiment was performed, using garden soil at 50% (v/v) and/or biochar at 2 or 5% (w/w). The results showed that biochar did not improve soil physico-chemical properties, neither did it affect plant parameters (dry weight, organ metal(loid)s concentrations). Moreover, higher metal(loid) concentrations were found in the roots compared to the upper parts. Finally, S. alba presented lower metal(loid) concentrations in the aboveground parts compared to S. viminalis, associated with a good growth, which make it a better candidate for phytostabilization of the studied soil.

Phytotoxicity Test to Assess Biochar Associated To Others Amendments Effect on Pb and As from Mining Technosol

Romain Nandillon, Manhattan Lebrun, Florie Miard, Marie Gaillard, Stéphane Sabatier, Sylvain Bourgerie, Fabienne Battaglia-Brunet, Domenico Morabito Université d’Orléans, LBLGC INRA USC1328 rue de Chartres, BP 6759, 45067 Orléans Cedex 2, France manhattan.lebrun@etu.univ-orleans.fr; florie.miard@univ-orleans.fr; domenico.morabito@univ-orleans.fr; sylvain.bourgerie@univ-orleans.fr IDDEA, Environmental Consulting Engineering 45160 Olivet, France romain.nandillon@iddea-ingenierie.fr; marie.gaillard@iddea-ingenierie.fr; stephane.sabatier@iddea-ingenierie.fr BRGM, ISTO, UMR 7327, BP 36009 45060 Orléans, France f.battaglia@brgm.fr Università degli Studi del Molise, Dipartimento di Bioscienze e Territorio 86090, Pesche, Italy

Capabilities of Fe-Functionalized Biochar to Decrease Soil Pb and As Phytodisponibility

Manhattan Lebrun, Florie Miard, Sullivan Renouard, Romain Nandillon, Gabriella S. Scippa, Domenico Morabito, Sylvain Bourgerie Université d’Orléans, LBLGC INRA USC1328 rue de Chartres, BP 6759, 45067 Orléans Cedex 2, France manhattan.lebrun@etu.univ-orleans.fr; florie.miard@univ-orleans.fr; romain.nandillon@univ-orleans.fr; domenico.morabito@univ-orleans.fr; sylvain.bourgerie@univ-orleans.fr Université d’Orléans, LBLGC INRA, USC 1328Antenne Scientifique Universitaire de Chartres, 21 Rue de Loigny La Bataille, 28000 Chartres, France sullivan.renouard@univ-orleans.fr Università degli Studi del Molise, Dipartimento di Bioscienze e Territorio 86090, Pesche, Italy scippa@unimol.it

Poplar Seeds Capabilities to Germinate on a Metal(Loid)S Contaminated Mining Technosol Differently Amended

Florie Miard, Romain Nandillon, Manhattan Lebrun, Marie Gaillard, Stéphane Sabatier, Sylvain Bourgerie, Domenico Morabito Université d’Orléans, LBLGC INRA USC1328 rue de Chartres, BP 6759, 45067 Orléans Cedex 2, France manhattan.lebrun@etu.univ-orleans.fr; florie.miard@univ-orleans.fr; domenico.morabito@univ-orleans.fr; sylvain.bourgerie@univ-orleans.fr IDDEA, Environmental consulting engineering 45160 Olivet, France romain.nandillon@iddea-ingenierie.fr; marie.gaillard@iddea-ingenierie.fr; stephane.sabatier@iddea-ingenierie.fr BRGM, ISTO, UMR 7327, BP 36009 45060 Orléans, France Università degli Studi del Molise, Dipartimento di Bioscienze e Territorio 86090, Pesche, Italy

Effect of Fe-functionalized biochar on toxicity of a technosol contaminated by Pb and As: sorption and phytotoxicity tests

Biochar, produced by the pyrolysis of biomass under low oxygen conditions, has gathered attention in the last few years due to its capability to reduce metal(loid)s bioavailability and mobility in soils, as well as its beneficial effects on soil fertility. Indeed, biochar amendment to polluted soil induced usually an increase of pH, water holding capacity, and nutrient contents, associated with a decrease of metal(loid)s concentrations in soil pore water, through sorption. However, biochar has been shown efficient in sorbing cation pollutants, like Pb, but present a low sorption capacity towards anions like As. This contrasted behavior poses a problem, as most polluted soils are multi-contaminated, with both cation and anion pollutants. One of the solutions to overcome such problem is to functionalize biochar, by modifying its surface. However, most studies actually focused on functionalization effect on metal(loid)s sorption towards batch experiments, and only a few dealt with modified biochar incorporation to the soil. Therefore, this study aimed (i) to assess the sorption capacity of hardwood biochars, harboring different particle sizes, towards Pb and As; (ii) to evaluate the effect of a Fe-functionalization on Pb and As sorption; and (iii) to validate the results, in a phytotoxicity test using Phaseolus vulgaris as bioindicator plant. The batch experiments showed that all four biochars were able to efficiently sorb Pb, the fine biochars showing higher sorption values than the coarse biochars. As sorption was very low. Fe-coating increased As sorption value, while having no effect on Pb sorption. However, when incorporated in the soil, Fe-coated biochar did not improve soil physico-chemical properties compared to the pristine biochar; especially, it did not reduce As soil pore water concentrations. Finally, bean plant did not show differences in terms of biomass production between the two biochars incorporated into polluted soil, demonstrating that Fe-functionalization did not improve biochar capacity to decrease soil toxicity.