Medicago truncatula genotype drives the plant nutritional strategy and its associated rhizosphere bacterial communities
Résumé
With the growing concern of developing a more sustainable agriculture, decreasing the use of inputs, and promoting biological diversity, harnessing plant microbiome through plant genetics is gaining of interest to improve plant growth, nutrition, and health. While genome-wide association studies have been conducted to identify plant genes driving the plant microbiome, more multidisciplinary studies are required to assess the relationships among plant the genetic effects, the plant microbiome and plant fitness. Using a metabarcoding approach, we characterized the rhizosphere bacterial communities of a core collection of 155 Medicago truncatula genotypes together with the plant phenotype, using an ecophysiological framework, and investigate the plant genetic effects through genome-wide association studies. The different genotypes within the M. truncatula core collection showed contrasted growth and carbon and nitrogen nutritional strategies but few loci were associated to these ecophysiological traits. To go further, we described its associated rhizosphere bacterial communities, dominated by Proteobacteria, Actinobacteria and Bacteroidetes, and defined a
core rhizosphere bacterial community. Next, occurrence of bacterial candidates predicting plant ecophysiological traits of interest were identified using random forest analyzes. Some of them were heritable and plant loci were identified, pinpointing genes related to response to hormone stimulus, systemic acquired resistance, response to stress, nutrient starvation ortransport, and root development.
Together, these results suggest that plant genetic can affect the plant growth and nutritional strategies harnessing keystones bacteria in a well-connected network community.