Harnessing plant traits to retain nitrogen in the rhizosphere

The aim is to unravel the controls exerted by plant traits on microorganisms performing two microbial processes that compete for nitrate, Dissimilatory Nitrate Reduction to Ammonium (DNRA) and denitrification, in the rhizosphere.

When not lost via leaching or taken up by the plants, these processes dictate whether nitrate is retained in the soil in the form of ammonium or lost as dinitrogen gas and the potent greenhouse gas nitrous oxide. Some DNRA bacteria can also act as N2O sinks by reducing N2O to harmless nitrogen gas. Knowledge of plant controls on DNRA as well as on the competition between the two processes is limited.

We will determine how plants traits involved in plant nitrogen acquisition and organic carbon exudation affect the communities of denitrifying and DNRA bacteria and the competition for nitrate in the rhizosphere.

We will also use (meta)genomic analyses to characterize the genetic potential for organic carbon metabolism and nitrous oxide sink/source capacity in these organisms.

The project thus combines molecular, isotopic and (meta)genomic approaches to generate a fundamental understanding of the interplay between plant traits, DNRA and denitrification.

This knowledge is a first step to the selection and breeding of crop varieties that in interplay with the soil microbial communities can concurrently increase nitrogen use efficiency of cropping systems and mitigate climate change.