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Université catholique de Louvain (2019)

Impact of arbuscular mycorrhizal fungi on durum wheat : analysis of genotypes colonization and response to Rhizophagus irregularis

Detroz, Clémence

Titre : Impact of arbuscular mycorrhizal fungi on durum wheat : analysis of genotypes colonization and response to Rhizophagus irregularis

Auteur : Detroz, Clémence

Université de soutenance : Université catholique de Louvain

Grade : Master : bioingénieur en sciences agronomiques 2019

Résumé
Global warming and less frequent but more intense rainfalls are all signs of climate change in Europe and worldwide. This will induce modifications in agricultural practices, since crops will be impacted by these major changes. Wheat (soft or durum) may be particularly affected by drought which may thus impact food production. That is why solutions to this issue need to be investigated. One of the potential paths is the use of arbuscular mycorrhizal fungi (AMF). These fungi have been shown to increase resistance/tolerance of several crops under controlled conditions via several mechanisms such as an increasing access to water resources in the soil. The overall objective of this master thesis is to study the root colonization of a large panel of genotypes grown in the field in Foggia (Puglia, Italy) and to assess on a selected number (high to low colonization levels and tolerant to sensitive genotypes) the effects of a selected AMF inoculant (Rhizophagus irregularis MUCL41833) on growth promotion. Fifteen genotypes out of 250 in the field were thus selected on basis of multiple criteria such as the AMF colonization level in the field or their sensitivity to drought. They were grown under controlled greenhouse conditions, with and without the AMF strain to investigate growth promotion. The results showed large differences of relative mycorrhizal dependency between the genotypes, with both negative and positive responses. Drought-tolerant genotypes presented a larger biomass than the drought-sensitive ones and the genotypes that were highly mycorrhized in the field presented larger biomass than the others. The results confirmed that each genotype has its own response to a specific AMF strain on a functional level. Two genotypes were further selected (one drought-tolerant and one drought-sensitive) with the same level of root colonization in the field, and the effects of drought inves- tigated under semi-hydroponic conditions. The objective was to investigate the impact of AMF on plant tolerance to a drought stress. All the plants from the drought-tolerant genotype unfortunately died before the completion of the experiment as well as the control (non-mycorrhized) plants of the drought-sensitive genotype. The analysis was thus limited to the impact of water regime on mycorrhized plants of that drought-sensitive genotype. The results showed a significant impact of water regime on the plants biomass, with smaller biomass for the poorly watered plants. The roots length was however not impacted by the water regime which could be attributed to the AMF presence and its additional water supply to the plant. However, without control plants this could not be confirmed. In conclusion, durum wheat is a mycotrophic plant whose response to AMF varies between genotypes. It is not excluded that AMF may help those genotypes to resist/tolerate drought stresses but whether and how drought-tolerant and drought-sensitive ones may react to AMF is still to be investigated.

Mots clés : Arbuscular Mycorrhizal Fungi (AMF), Durum wheat, Genotypes, Rhizophagus irregularis MUCL41833, Drought stress, SolACE project

Présentation

Page publiée le 14 janvier 2020