Beneficial soil-borne bacteria and fungi: a promising way to improve plant nitrogen acquisition

Abstract

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. 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. 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 also fix N. These include bacteria of the genera Azospirillum, Azotobacter, and Bacillus, some of which are commercialized as bio-inoculants. Arbuscular mycorrhizal fungi are other microorganisms that can develop symbiotic associations with most terrestrial plants, favoring access to nutrients in a larger soil volume through their extraradical 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. Complex biological mechanisms including molecular, metabolic, and physiological processes dictate the establishment and efficiency of such multipartite symbiotic associations. 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.

Manipulating Amino Acid Metabolism to Improve Crop Nitrogen Use Efficiency for a Sustainable Agriculture

“…A major beneficial effect of bacteria on plant N acquisition is the symbiotic relationship between rhizobia and leguminous plants (Dellagi et al, 2020). While this bacteria-plant symbiotic interaction essentially occurs within Fabaceae, some plantgrowth-promoting rhizobacteria and arbuscular mycorrhizal fungi with a wide-range of specificity for crops may have an interesting potential for the improvement of plant N nutrition that should be further evaluated.…”

Exploiting Biological Nitrogen Fixation: A Route Towards a Sustainable Agriculture

“…However, the excessive use of this nitrogen source leads to soil acidification [ 136 ]. Therefore, for several years scientists have tried to find a way to reduce dependence on chemical fertilizers through engineering crop plants to fix nitrogen they need for their growth and yield [ 49 , 134 , 136 , 137 ]. This process was restricted primarily to legumes in agricultural system.…”

Bacterial Plant Biostimulants: A Sustainable Way Towards Improving Growth, Productivity, and Health of Crops

“…Azotobacter [32], Bacillus [21], and Pseudomonas [50]. A great number of PGPRs produce cytokinins and gibberellins [59], though the roles of bacteria in the regulation of plant hormones and the bacterial mechanism involved in their synthesis are largely not understood yet.…”