Skip to Main content Skip to Navigation
Theses

Molecular approaches to study oxidative stress tolerance mechanisms in the ericoid mycorrhizal fungus Oidiodendron maius

Abstract : Due to increasing anthropogenic activities, large areas are highly contaminated by heavy metals which are affecting biological systems. Oidiodendron maius strain Zn could be an interesting organism in a bioremediation program being both an ericoid mycorrhizal fungus and a heavy metal-tolerant strain. To understand the mechanisms underlying the oxidative stress tolerance of this strain, three different approaches were used. The first approach allowed us to obtain superoxide dismutase 1 (SOD1) null mutants. The most important technical advance in this work was the first successful disruption of a gene by homologous recombination in a mycorrhizal fungus. We demonstrate that the lack of OmSOD may cause an imbalance in the redox homeostasis and an alteration in the delicate dialogue between the fungus and its host plant. The second approach was based on a yeast functional complementation screening using an O. maius cDNA library. In this work we report the first transporters of an ericoid mycorrhizal fungus capable of conferring Zn tolerance to yeast transformants. Two full-length cDNAs were isolated and named OmCDF and OmFET. The heterologous expression of these two genes in various yeast mutants conferred resistance to zinc. Additionally, OmCDF expression also conferred Co tolerance. We provide evidence that OmCDF functions as a Zn transporter responsible for relocating cytoplasmic Zn into the endoplasmic reticulum, whereas expression of OmFET could counteract Zn toxicity by increasing Fe content of cells. The third approach consisted in the screening of a collection of O. maius random-mutants on Zn, Cd and menadione. We report the characterization of an O. maius-mutant that carries a mutation in the nmr gene. In this mutant, a decrease of glutamine and asparagine pools, and a reduction of the activity of glutamine synthase were recorded. Possible links between the oxidative stress tolerance and the nitrogen metabolism are discussed.
Document type :
Theses
Complete list of metadatas

Cited literature [61 references]  Display  Hide  Download

https://hal.univ-lorraine.fr/tel-01746186
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 10:26:31 AM
Last modification on : Thursday, January 7, 2021 - 3:44:01 PM
Long-term archiving on: : Thursday, September 13, 2018 - 1:22:22 PM

File

SCD_T_2011_0033_KHOUJA.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01746186, version 1
  • PRODINRA : 277240

Collections

Citation

Hassine Radhouane Khouja. Molecular approaches to study oxidative stress tolerance mechanisms in the ericoid mycorrhizal fungus Oidiodendron maius. Vegetal Biology. Université Henri Poincaré - Nancy 1, 2011. English. ⟨NNT : 2011NAN10033⟩. ⟨tel-01746186⟩

Share

Metrics

Record views

277

Files downloads

133