Séminaire thématique : "Le cycle de l'azote"

Nitrogen (N) is an essential element for plant productivity, thus, it is abundantly applied to the soil in the form of organic or chemical fertilizers that have negative impacts on the environment.  Nitrogen use efficiency (NUE) is the capacity of crop to valorize N present in the soil for the production of biomass.  Currently, there are three major targets for enhancing NUE in agriculture: (i) plant breeding (ii) employing alternative and improved agronomic practices, and (iii) utilizing the beneficial effects of microbes through the study of plant microbiota. Exploiting the potential of beneficial microbes and identifying crop genotypes that can capitalize on symbiotic associations may be possible ways to significantly reduce the use of N fertilizers while maintaining yields. The best-known example of symbiotic association that can reduce the use of N fertilizers is the N2-fixing rhizobial bacteria and legumes. Bacterial taxa other than rhizobial species can develop associative symbiotic interactions with plants and fix N2. Arbuscular mycorrhizal fungi (AMF) are other microorganisms that can develop symbiotic associations with most terrestrial plants, favoring access to N nutrients in a larger soil volume through their extra-radical mycelium. Using combinations of different beneficial microbial species is a promising strategy to boost plant N acquisition and foster a synergistic beneficial effect between symbiotic microorganisms. In this review, we present an overview of the current knowledge and future prospects regarding plant N nutrition improvement through the use of beneficial bacteria and fungi associated with plants, individually or in combination.