Metal phytotoxicity

Group leader: Françoise Gosti
Research Associate CNRS



Group leader: Claude Nespoulous
Research Associate INRAE



Key words

genetic, genomic and functional approaches, hyper-accumulating plants, wheat, tobacco, plant defensins


The scientific objectives of our team are to identify and characterize mechanisms controlling (i) metal tolerance of plants and (ii) metal accumulation in plants. This work can be connected to two general topics: “phytoremediation of metal polluted soils” and “food safety”. We mainly work on zinc and cadmium. Two approaches are developed. The first one aims at characterizing naturally metal tolerant and metal hyper-accumulating plant species: we try to understand which mechanisms are at the origin of the acquisition of the zinc hypertolérance and zinc hyperaccumulation traits in Arabidopsis halleri. The second approach starts with an analysis of the natural diversity for traits related to metal tolerance or metal accumulation, which is pursued by a QTL approach. We thus tracked determinants controlling zinc tolerance in Arabidopsis thaliana as well as cadmium accumulation in lettuce. The team develops genetics, biochemistry and molecular physiology approaches. Our principal results are the following : We showed that zinc tolerance was also observed at the cellular level in A. halleri. On the basis of this observation, we demonstrated that defensins, which were up to now only known as antifungal or antimicrobial proteins, play a role in the cellular tolerance to zinc. We currently analyze the regulation of the expression of these defensins, which are highly expressed in A. halleri, as well as the cellular mechanism by which defensins can confer zinc tolerance. We also characterized the 5 tonoplastic zinc transporters constituting the MTP1 family in A. halleri, and proposed that the evolutionary forces working on these transporters were probably of different nature according to the member of the family. About our analyses of the natural diversity and our QTL approach we showed that zinc tolerance and zinc accumulation were not linked in A. thaliana. A similar result was found concerning cadmium in lettuce. In A. thaliana, several zinc tolerance QTLs were identified and the gene corresponding to one of them was identified by positional cloning. In lettuce, a combination of genetic, molecular and physiological approaches enabled us to propose that the capacity to exclude cadmium from the roots back to the culture medium was a major factor limiting cadmium accumulation in plant tissues.

Team members
Main results
Belgaroui N, Berthomieu P, Rouached H, Hanin M (2016) The secretion of the bacterial phytase PHY-US417 by Arabidopsis roots reveals its potential for increasing phosphate acquisition and biomass production during co-growth. Plant Biotechnol. J., 14(9):1914-1924

Phytic acid (PA) is a major source of inorganic phosphate (Pi) in the soil. Plants are however unable to use PA for Pi nutrition and growth. Arabidopsis was engineered to secrete a bacterial phytase. Compared to the control, it showed normal growth and no hallmark of Pi deficiency when grown on phytic acid as sole P source. Interestingly, co-cultivation of the engineered plants with controls showed that the secreted phytases benefitted to the neighbouring control plants, which showed no sign of Pi deficiency and normal growth.

The work was done in collaboration with the Centre de Biotechnologie de Sfax in Tunisia.

Significant publications
Auguy F, Fahr M, Moulin P, El Mzibri M, Smouni A, Filali-Maltouf A, Béna G, Doumas P (2016) Transcriptome changes in Hirschfeldia incana in response to lead exposure. Front. Plant Sci., 6:1231

Belgaroui N, Berthomieu P, Rouached H, Hanin M (2016) The secretion of the bacterial phytase PHY-US417 by Arabidopsis roots reveals its potential for increasing phosphate acquisition and biomass production during co-growth. Plant Biotechnol. J., 14(9):1914-1924

Bouain N, Doumas P, Rouached H (2016) Recent advances in understanding the molecular mechanisms regulating the root system response to phosphate deficiency in Arabidopsis. Curr. Genomics, 17(4):308-314

Doumas P, Munoz M, Banni M, Becerra S, Bruneel O, Casiot C, Cleyet-Marel J-C, Gardon J, Noack Y, Sappin-Didier V (2017) Polymetallic pollution from abandoned mines in Mediterranean regions: a multidisciplinary approach to environmental risks. Reg. Environ. Change, (in press)

Kozhevnikova AD, Seregin IV, Gosti F, Schat H (2017) Zinc accumulation and distribution over tissues in Noccaea caerulescens in nature and in hydroponics: a comparison. Plant Soil, 411(1):5-16

Saenchai C*, Bouain N*, Kisko M, Prom-U-Thai C, Doumas P, Rouached H (2016) The involvement of OsPHO1;1 in the regulation of iron transport through integration of phosphate and zinc deficiency signalling. Front. Plant Sci., 7:396

Saenchai C, Prom-U-Thai C, Lordkaew S, Rouached H, Rerkasem B (2016) Distribution of iron and zinc in plant and grain of different rice genotypes grown under aerobic and wetland conditions. J. Cereal. Sci., 71:108-115

Fahr M, Laplaze L, El Mzibri M, Doumas P, Bendaou N, Hocher V, Bogusz D, Smouni A (2015) Assessment of lead tolerance and accumulation in metallicolous and non-metallicolous populations of Hirschfeldia incana. Environ. Exp. Bot., 109:186-192

Kisko M*, Bouain N*, Rouached A*, Choudhary SP, Rouached H (2015) Molecular mechanisms of phosphate and zinc signaling crosstalk in plants: Phosphate and zinc loading into root xylem in Arabidopsis. Environ. Exp. Bot., 114:57-64

Mith O, Benhamdi A, Castillo T, Bergé M, MacDiarmid CW, Steffen J, Eide DJ, Perrier V, Subileau M, Gosti F, Berthomieu P, Marquès L (2015) The antifungal plant defensin AhPDF1.1b is a beneficial factor involved in adaptive response to zinc overload when it is expressed in yeast cells. Microbiology Open, 4(3):409-422

Belgaroui N, Zaidi I, Farhat A, Chouayekh H, Bouain N, Chay S, Curie C, Mari S, Masmoudi K, Davidian J-C, Berthomieu P, Rouached H, Hanin M (2014) Overexpression of the bacterial phytase US417 in Arabidopsis reduces the concentration of phytic acid and reveals its involvement in the regulation of sulfate and phosphate homeostasis and signaling. Plant Cell Physiol., 55(11):1912-1924

Bouain N, Kisko M, Rouached A, Dauzat M, Lacombe B, Belgaroui N, Ghnaya T, Davidian J-C, Berthomieu P, Abdelly C, Rouached H (2014) Phosphate/zinc interaction analysis in two lettuce varieties reveals contrasting effects on biomass, photosynthesis, and dynamics of Pi transport. Biomed Res. Int., 2014:548254

Bouain N*, Shahzad Z*, Rouached A*, Khan GA, Berthomieu P, Abdelly C, Poirier Y, Rouached H (2014) Phosphate and zinc transport and signalling in plants: toward a better understanding of their homeostasis interaction. J. Exp. Bot., 65(20):5725-5741

Hermand V, Julio E, Dorlhac de Borne F, Punshon T, Richachenevsky FK, Bellec A, Gosti F, Berthomieu P (2014) Inactivation of two newly identified tobacco heavy metal ATPases leads to reduced Zn and Cd accumulation in shoots and reduced pollen germination. Metallomics, 6(8):1427-1440

Khan GA, Bouraine S, Wege S, Li Y, de Carbonnel M, Berthomieu P, Poirier Y, Rouached H (2014) Coordination between zinc and phosphate homeostasis involves the transcription factor PHR1, the phosphate exporter PHO1, and its homologue PHO1;H3 in Arabidopsis. J. Exp. Bot., 65(3):871-884

Meindre F, Lelièvre D, Loth K, Mith O, Aucagne V, Berthomieu P, Marquès L, Delmas AF, Landon C, Paquet F (2014) The nuclear magnetic resonance solution structure of the synthetic AhPDF1.1b plant defensin evidences the structural feature within the γ-motif. Biochemistry-US, 53(49):7745-7754

Nguyen NNT, Ranwez V, Vile D, Soulié M-C, Dellagi A, Expert D, Gosti F (2014) Evolutionary tinkering of the expression of PDF1s suggests their joint effect on zinc tolerance and the response to pathogen attack. Front. Plant Sci., 5:70

Auguy F, Fahr M, Moulin P, Brugel A, Laplaze L, El Mzibri M, Filali-Maltouf A, Doumas P, Smouni A (2013) Lead tolerance and accumulation in Hirschfeldia incana, a Mediterranean Brassicaceae from metalliferous mine spoils . PLoS one, 8(5):e61932

Rouached H (2013) Recent developments in plant zinc homeostasis and the path toward improved biofortification and phytoremediation programs. Plant Signal. Behav., 8(1):e22681

Shahzad Z, Ranwez V, Fizames C, Marquès L, Le Martret B, Alassimone J, Godé C, Lacombe E, Castillo T, Saumitou-Laprade P, Berthomieu P, Gosti F (2013) Plant Defensin type 1 (PDF1): protein promiscuity and expression variation within the Arabidopsis genus shed light on zinc tolerance acquisition in Arabidopsis halleri. New Phytol., 200(3):820-833

Former team members

Thesis defended by Jérémy Bertrand

Nov 30, 2018 – Identification de déterminants génétiques impliqués dans le contrôle de l’accumulation de cadmium chez le tabac (Nicotiana tabacum L.)

Thesis defended by Mohanad Alsulaiman

Sep 13, 2018 – Physiological responses to zinc excess in Arabidopsis non-extremophile and extremophile plant species : interaction with drought and role of plant

Thesis defended by Nibras Belgaroui

Dec. 17, 2016 – Physiological and molecular dissection of phytic acid role in response of plant to environmental stress

Thesis defended by Nadia Bouain

Jun. 30, 2016 – Sudy of interactions between heavy metals and phosphate homeostasis in plants : physiological and molecular basis

Thesis defended by Oriane Mith

Sep. 19, 2014 – of the mode of action of plant defensin AhPDF1.1b in the tolerance to zinc

Thesis defended by Thi Ngoc Nga Nguyen

Mar. 24, 2014 – Functional expression of Plant Defensins type 1 for zinc tolerance in plants