A new generation of eco-friendly inoculants driving sustainable agriculture

Improving the bacterial genetics used in Latin America and Spain through the development of inoculants capable of increasing productivity and nutritional quality of regional crops, as well as reducing nitrous oxide emissions

Context of the story

The bacteria present in agricultural soils account for 60% of nitrous oxide (N2O) emissions, one of the three main greenhouse gases responsible for global warming. Paradoxically, agriculture is highly vulnerable to climate change. Furthermore, unlike the continuous genetic improvement seen in plants and animals, there have been no significant advances in the genetics of bacterial inoculants used worldwide in the last three decades. In this context, understanding the genetic background related to high N2O emissions in traditional inoculants, as well as improving their genetics, represents a unique opportunity for the development of a new technological package to combat global climate change.

Understanding and improving the genetics of traditional inoculants.

The implemented initiative

With support from FONTAGRO and their own resources, INTA, UNSAM, CONICET, IIBCE, UNC, UNFRO, CSIC, and EMBRAPA have started promoting technological innovations in the field of inoculants. The objective was to develop a new technological package that combines three benefits simultaneously: (i) applicability to different regional crops, (ii) increased production and quality of these crops, and (iii) significant reduction in nitrous oxide emissions. To achieve this objective, the identification of new bacterial isolates with PGPR activity is being encouraged, and the study of the domestication process of traditional inoculants is also being promoted. These efforts enable the design of rational strategies for genetic improvement.

Bacterial genetic improvement.

The technological solution

Due to the intrinsic biological characteristics of microorganisms (including high dispersal power and extensive genetic flow), the commercial deregulation of recombinant inoculants (GMO) would be an extremely costly process. As a result, no recombinant inoculants have been released globally to date. As such, the technological solutions developed in this project are based on the use of new microbial genetics that can be considered non-GMO by the competent authorities. The main focus is on the identification of new natural isolates with different plant growth-promoting properties and the selection of spontaneous mutants derived from traditional inoculants. Within this latter group, spontaneous mutants with increased nitrogen fixation activity, greater tolerance to abiotic stress, enhanced glyphosate degradation, and reduced nitrous oxide emissions are particularly noteworthy.

"Understanding and improving the genetics of microorganisms allows us to unleash the potential of sustainable and resilient agricultural practices"

Mariangela Hungria - EMBRAPA - (Fundación Bunge Award 2022)

Participating countries

Type of project

Results

• The molecular mechanism by which traditional inoculants produce high N2O emissions has been identified. During the domestication process (1960-1990), these bacteria retained the production genes (NAP, NIR, and NOR) but lost the N2O degradation genes (NOS). This knowledge has allowed for the rational design of genetic improvement strategies (selection of NAP, NIR, and/or NOR mutants) for traditional inoculants and the analysis of the potential environmental safety of new isolates.
• Six new molecular mechanisms have been identified to increase tolerance to abiotic stress, nitrogen fixation, and glyphosate in bacteria (glxA F208L, GltL KO, Cya KO, ZigA D186A, BetA S100A, and NifH S90A). These mutations can be induced by point substitutions generated both by spontaneous mutations and base editors.
• The economic and environmental benefits of 18 new strains in 11 regional crops have begun to be characterized.