Asmaa Agoussar

Institut National de la Recherche Scientifique. Institut Armand-Frappier.
Creation of synthetic wheat holobionts for increased drought resistance

Asmaâ Agoussar, Hamed Azarbad, Etienne Yergeau

Drought is a limiting factor in agricultural production, and will become a major problem with the predicted climate changes. The relationships between the plant and its microbiota (collectively known as a holobiont) could be the key to overcome this issue. Our objective is to create a synthetic holobiont from a collection of strains thoroughly tested for their beneficial effect on wheat drought tolerance. An extended culture collection of bacteria and fungi was created from leaves, roots and rhizosphere soils of field-grown wheat plants under reduced or normal precipitation levels (25 or 100% of the natural precipitation). The strains were isolated on traditional (TSA for bacteria or PDA for fungi) and specialized, environmentally relevant (soil extract, leaf extract, artificial root exudates) growth media. So far, we have isolated 200 strains of bacteria and 50 strains of fungi, representing a significant part of the OTUs found in 16S rRNA gene and ITS region amplicon sequencing datasets produced from the same samples. The strains are currently being characterized for their capacity to promote root elongation and plant tolerance to stress under low soil water content. Synthetic communities will then be assembled and combined with various drought tolerant or sensitive wheat cultivars to create synthetic holobionts. These holobionts will then be compared in term of their capacity to sustain water-stress. Future experiments will further zoom in the metatranscriptomic responses of these holobionts to water stress. Our results are expected to shed light on the microbial community characteristics necessary for improved water-stress tolerance of wheat holobionts.