Doctorate thesis of Montpellier University


Wednesday, December 13, 2019

at 2 PM –Campus de La Gaillarde- Amphi 208 (School Heart)


Root developmental responses to nutrient shortage and biotic conditions in wheat: identification of beneficial bacteria from wheat rhizosphere and new procedures for phenotyping root and root hair development


Doctoral School: GAIA – Biodiversity, Agriculture, Food, Environment, Land, Water
Speciality: BIDAP – Biology, Interactions, Adaptive Plant Diversity
Institution: University of Montpellier


M. Jean-Marc ALLAIN, Professeur, Ecole polytechnique, Palaiseau Rapporteur
M. Jean-Marie FRACHISSE, Chargé de recherche, CNRS, Gif-sur-Yvette Rapporteur
Mme. Brigitte BRUNEL, Professeur, SupAgro, Montpellier Examinatrice
Mme. Maïté VICRÉ-GIBOUIN, Maître de conférences, Université de Rouen, Rouen Examinatrice
M. Hervé SENTENAC, Directeur de recherche, INRA, Montpellier Directeur de thèse
M. Jean-Benoît PELTIER, Chargé de recherche, INRA, Montpellier Encadrant

Reducing chemical fertilization and its ecological costs is one of the major challenges in agriculture. Knowledge has thus to be gained about root development and physiological functions contributing to plant mineral nutrition. This includes interactions with beneficial soil microbes directly or indirectly improving nutrient ion acquisition. At the root surface, root hairs are at the crossroad of plant nutrition and interactions with beneficial soil microbes. Members from a collection of 16 bacterial strains that we have isolated from wheat rhizospheric soils, comprising species belonging to the genera Achromobacter, Stenotrophomonas, Rhizobium, Paraburkholderia and Klebsiella, are shown to differ with respect to their ability to solubilize poorly soluble sources of phosphate and potassium, their effects on nutrient ion acquisition and nitrate use efficiency, their impact on root development and root hair elongation, and finally their capacity to promote wheat growth. New phenotyping methodologies have been developed, involving original growth devices and in silico image analysis programs, in order to describe with quantitative parameters root and root hair development in response to abiotic and biotic conditions. A first set of experiment shows distinctive responses, in terms of root growth and root hair development, to low availability of phosphate or nitrogen and to inoculation with a Bradyrhizobium japonicum strain in 2‑week‑old wheat seedlings (Triticum turgidum L. spp. durum cv. Oued Zenati).

Key words: Wheat, root, root hair, mineral nutrition, PGPR (Plant Growth Promoting Rhizobacteria)