ZIFL1.1 transporter modulates polar auxin transport by stabilizing membrane abundance of multiple PINs inArabidopsisroot tip

Cell-to-cell directional flow of the phytohormone auxin is primarily established by polar localization of the PIN auxin transporters, a process tightly regulated at multiple levels by auxin itself. We recently reported that, in the context of strong auxin flows, activity of the vacuolar ZIFL1.1 transporter is required for fine-tuning of polar auxin transport rates in the Arabidopsis root. In particular, ZIFL1.1 function protects plasma-membrane stability of the PIN 2 carrier in epidermal root tip cells under conditions normally triggering PIN 2 degradation. Here, we show that ZIFL1.1 activity at the root tip also promotes PIN 1 plasma-membrane abundance in central cylinder cells, thus supporting the notion that ZIFL1.1 acts as a general positive modulator of polar auxin transport in roots.FCT fellowship: (SFRH/BPD/44640/2008)

Heterologous expression of the yeast Tpo1p or Pdr5p membrane transporters in Arabidopsis confers plant xenobiotic tolerance

This deposit is composed by the main article plus the supplementary materials of the publication.Soil contamination is a major hindrance for plant growth and development. The lack of effective strategies to remove chemicals released into the environment has raised the need to increase plant resilience to soil pollutants. Here, we investigated the ability of two Saccharomyces cerevisiae plasma-membrane transporters, the Major Facilitator Superfamily (MFS) member Tpo1p and the ATP-Binding Cassette (ABC) protein Pdr5p, to confer Multiple Drug Resistance (MDR) in Arabidopsis thaliana. Transgenic plants expressing either of the yeast transporters were undistinguishable from the wild type under control conditions, but displayed tolerance when challenged with the herbicides 2,4-D and barban. Plants expressing ScTPO1 were also more resistant to the herbicides alachlor and metolachlor as well as to the fungicide mancozeb and the Co(2+), Cu(2+), Ni(2+), Al(3+) and Cd(2+) cations, while ScPDR5-expressing plants exhibited tolerance to cycloheximide. Yeast mutants lacking Tpo1p or Pdr5p showed increased sensitivity to most of the agents tested in plants. Our results demonstrate that the S. cerevisiae Tpo1p and Pdr5p transporters are able to mediate resistance to a broad range of compounds of agricultural interest in yeast as well as in Arabidopsis, underscoring their potential in future biotechnological applications.Fundação para a Ciência e a Tecnologia grants: (EXPL/AGR-PRO/1013/2013, PTDC/BIA-PLA/1084/2014, SFRH/BPD/44640/2008, SFRH/BPD/81221/2011, PD/BD/105735/2014, PD/00133/2012, SFRH/BD/92552/2013, UID/BIO/04565/2013, UID/Multi/04551/2013). Programa Operacional Regional de Lisboa 2020 grant: (Project N. 007317).info:eu-repo/semantics/publishedVersio

Intron retention in the 5'UTR of the novel ZIF2 transporter enhances translation to promote zinc tolerance in arabidopsis

Root vacuolar sequestration is one of the best-conserved plant strategies to cope with heavy metal toxicity. Here we report that zinc (Zn) tolerance in Arabidopsis requires the action of a novel Major Facilitator Superfamily (MFS) transporter. We show that ZIF2 (Zinc-Induced Facilitator 2) localises primarily at the tonoplast of root cortical cells and is a functional transporter able to mediate Zn efflux when heterologously expressed in yeast. By affecting plant tissue partitioning of the metal ion, loss of ZIF2 function exacerbates plant sensitivity to excess Zn, while its overexpression enhances Zn tolerance. The ZIF2 gene is Zn-induced and an intron retention event in its 5'UTR generates two splice variants (ZIF2.1 and ZIF2.2) encoding the same protein. Importantly, high Zn favours production of the longer ZIF2.2 transcript, which compared to ZIF2.1 confers greater Zn tolerance to transgenic plants by promoting higher root Zn immobilization. We show that the retained intron in the ZIF2 5'UTR enhances translation in a Zn-responsive manner, markedly promoting ZIF2 protein expression under excess Zn. Moreover, Zn regulation of translation driven by the ZIF2.2 5'UTR depends largely on a predicted stable stem loop immediately upstream of the start codon that is lost in the ZIF2.1 5'UTR. Collectively, our findings indicate that alternative splicing controls the levels of a Zn-responsive mRNA variant of the ZIF2 transporter to enhance plant tolerance to the metal ion.FCT PostDoctoral Fellowships: SFRH/BPD/44640/2008, SFRH/BPD/81221/2011

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Altimetry for the future: building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Caractérisation de mutants de Leptosphaeria maculans obtenus par agrotransformation et affectés dans leur pouvoir pathogène

Leptosphaeria maculans est l ascomycete responsable de la maladie la plus dommageable sur colza, la nécrose du collet. C est un champignon hémibiotrophe au cycle parasitaire complexe et exemplaire des stratégies d infection des Dothidéomycètes. Le déterminisme moléculaire du pouvoir pathogène de L. maculans est actuellement mal connu et seuls deux gènes impliqués dans le pouvoir pathogène étaient décrits et validés au début de cette thèse. De façon à accroître notre compréhension du déterminisme du pouvoir pathogène, une stratégie de mutagenèse insertionnelle aléatoire via Agrobacterium tumefaciens a été mise en place. L intérêt de cette approche pour l identification de mutants affectés dans leur pouvoir pathogène et étiquetés a tout d abord été validé, puis nous avons développé une analyse phénotypique et moléculaire plus détaillée de trois des mutants de la collection.Les trois mutants sélectionnés (m210, m20 et m186) sont non pathogènes et affectés à des étapes différentes du processus infectieux : la phase de germination à la surface de l hôte pour m210, la phase de colonisation biotrophe pour m20 et la transition biotrophie-nécrotrophie pour m186. Pour chacun des mutants, une intégration unique de l ADN-T a été mise en évidence. Dans les trois cas, celle-ci a eu lieu dans des régions promotrices, conduisant à une dérégulation de l expression des gènes adjacents au site d intégration (sur-expression pour m186, réduction de 40% pour m210, sur-expression in vitro et sous-expression in planta pour m20). L implication de chacun des gènes responsables du phénotype mutant, ainsi que leur fonction et leur rôle dans le pouvoir pathogène ont ensuite été analysés par différentes approches (bio-informatique, complémentation fonctionnelle, silencing, etc ).The Ascomycete Leptosphaeria maculans is responsible for the most damaging disease of oilseed rape (Brassica napus), stem canker. This hemibiotrophic fungus possess a complex parasitic cycle and is representative of Dothideomycete infection strategies. The molecular determinism of L. maculans pathogenicity is currently poorly understood with only two pathogenicity genes described and validated at the beginning of this thesis. Thus, the first objective of this PhD was to initiate a random insertional mutagenesis strategy using Agrobacterium tumefaciens-mediated transformation in order to increase our knowledge on L. maculans pathogenicity factors. We first validated the robustness of this approach to identify loss-of pathogenicity tagged mutants, then we performed a more detailed phenotypic and molecular characterisation of three mutants of the collection. The three non pathogenic mutants selected (m20, m210 and m186) are affected in three different steps of the infection process: the germination phase on the host surface for m210, the biotrophic colonisation phase for m20 and the switch between biotrophy and necrotrophy for m186. A single copy integration event of the T-DNA occurred in each mutant. In addition, all integrations took place in promoter regions, leading to a deregulation of the expression of the closest genes (over-expression for m186, 40% reduction of expression for m210, and over-expression in vitro and reduction in planta for m20). Identification of the gene responsible for the mutant phenotype, along with its intrinsic function and role in pathogenicity were then analysed using various approaches (bioinformatics, functional complementation, silencing, etc...).ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Beyond cellular detoxification: a plethora of physiological roles for MDR transporter homologs in plants

Higher plants possess a multitude of Multiple Drug Resistance (MDR) transporter homologs that group into three distinct and ubiquitous families — the ATP-Binding Cassette (ABC) superfamily, the Major Facilitator Superfamily (MFS), and the Multidrug And Toxic compound Extrusion (MATE) family. As in other organisms, such as fungi, mammals and bacteria, MDR transporters make a primary contribution to cellular detoxification processes in plants, mainly through the extrusion of toxic compounds from the cell or their sequestration in the central vacuole. This review aims at summarizing the currently available information on the in vivo roles of MDR transporters in plant systems. Taken together, these data clearly indicate that the biological functions of ABC, MFS and MATE carriers are not restricted to xenobiotic and metal detoxification. Importantly, the activity of plant MDR transporters also mediates biotic stress resistance and is instrumental in numerous physiological processes essential for optimal plant growth and development, including the regulation of ion homeostasis and polar transport of the phytohormone auxin