DARRIAUT Romain

Nationality: France
Email: romain.darriaut@inra.fr

Thesis title

Microbiome role in the rhizosphere functionning of different grapevine rootstocks and impact on scion growth.

• Doctoral school: Life and Health Sciences - University of Bordeaux
• Supervisor : Virginie LAUVERGEAT
• Funding : FranceAgriMer
• Project : VITIRHIZOBIOME

Abstract

Rootstocks are used in numerous cultures to control plant growth by improving water and mineral nutrition, tolerance to soil pathogens and abiotic stresses. In grapevine, as in other fruit trees, the rootstock contributes to the development of the scion depending on environmental conditions and thus to the yield and quality of the berries. The physiological and molecular bases of the morphological and functional responses of the grapevine root system in response to abiotic constraints are still poorly known, partly because of the difficulty of characterizing the roots in situ, the complexity of the adaptive traits analysed, and the structure and composition of vineyard soils. The interaction between the roots and the soil microbiome plays an essential role in the acquisition of the mineral and water resources that are required for the optimal development of the plant. The symbiotic association with arbuscular mycorrhiza allows, not only a better acquisition of nutrients such as phosphorus and nitrogen, but also plays a role in the resistance of plants to some soil pathogens. In order have a better understanding in the importance of the rootstock genotype in adaptation processes to environmental constraints and in the development of the grafted plant, this project will focus on the functioning of the rhizosphere in a dieback soil condition. The objective of this work will be to acquire knowledge on the functioning of the grafted grapevine by focusing on the root development and the adaptive mechanisms that regulate the hydro-mineral acquisition by the root system for different genotypes of rootstocks. The work done will answer the following questions:
- Do grapevine rootstocks, previously characterized for their contrasting ability to regulate scion development, have different abilities to establish functional symbiotic interactions with arbuscular mycorrhiza? - To what extent does grafting play a role in the regulation of these processes?
- What is the effect of soil quality on the rhizosphere and the functioning of the mycorrhizal symbiosis and its effect on the development of the grafted plant?
Experiments in semi-controlled conditions using vineyard soils will be conducted to answer those different questions. Two rootstocks, 1103Paulsen and Riparia Gloire de Montpellier, inducing respectively a strong and a low vigour of the scion, will be studied. Their ability to form symbioses with Rhizophagus irregularis, and/or Glomus mosseae (arbuscular mycorrhizal fungi), in dieback soils will be quantified by microscopy and molecular biology approaches. The mechanisms involved in the establishment of the symbiotic interaction in these two rootstocks will be studied. Plants will be also submitted to biostimulants applications (commercial and PGPR) in order to evaluate their impacts in a dieback soil condition. The effect on plant physiology and development will be evaluated. The effect of grafting will be assessed by performing different combinations of rootstock / scion. In parallel, the microbial diversity of the soil will be analysed in collaboration with the UR Oenology (ISVV). Functional interactions between the soil microbiome and the seedlings of both rootstocks will be characterized. In parallel, to get closer to field conditions, a trial will be conducted in a vineyard to assess the effect of mycorrhizal symbiosis and some PGPR, isolated from previous experiments, on the recovery of plants and their development. This trial will be conducted in collaboration with Vitinnov, ISVV transfer cell.

Publications