Amandine Ducousso

Université de Montréal
Ph.D. candidate

Supervisor: Mohamed Hijri
L.H. Anissa, Université du Littoral et Côte d'Opale
Start: 2018-10-01
End: 2021-08-31


Influence of plant-microbe-mycorrhizal fungi interaction on the biological dissolution of phosphates
The spectacular advances in next-generation sequencing technologies have made it possible to study in detail the microbiota of agricultural soils and roots of field crops and to highlight numerous microorganisms of agronomic interest. Among these microorganisms, arbuscular mycorrhizal fungi (AMF) are obligate biotrophs capable of symbiosis with 80% of terrestrial plants. The interest and use of AMCs and their associated bacteria in agriculture is growing dramatically around the world. In addition to their roles in protecting plants against pathogens and organic and inorganic soil pollutants, they play an important role in capturing minerals essential for plant growth, including phosphorus, while allowing the plant better water supply during dry periods. Hence the interest of their use in agriculture as biofertilizers, certain phosphate solubilizing microbes such as bacteria and fungi can enhance the functions of CMAs in the dissolution and assimilation of natural phosphates present in soil or igneous or sedimentary phosphate rock. However, the importance of microbes associated with mycorrhizal fungi, the effects of plant-microbe-mycorrhizal fungi interaction in the solubilization of phosphates and the assimilation of nutrients, remain very little known. Thus, the general objective of this doctoral project is to study the effect of the interaction of beneficial microorganisms and plants on the solubilization of sedimentary or igneous phosphorus rock and the assimilation of macroelements by plants for sustainable agriculture. The specific objectives are: [1] To study the microbiota biodiversity associated with spores and mycelia (bacteria and fungi living on the surface or inside) of CMAs isolated from soils rich in non-bioavailable phosphates, using amplicon sequencing and microbial isolation approach. [2] Investigate the ability and mechanisms of CMA-associated microorganisms to solubilize phosphates, using culture media implemented by phosphate rock apatite, and by analyzing organic acids by HPLC. [3] To study the effect of plant-microbe-arbuscular mycorrhizal fungi interaction on the solubilization of phosphates in vitro and in planta, using culture media implemented by apatite and greenhouse rock phosphate trials as the only source of phosphorus.


Plant Growth Promoting Rhizobacteria, arbuscular mycorrhizal fungi (AMF), Phosphate solubilization, root bacterial communities