☆ 4.6 Review

Molecular Biology in the Improvement of Biological Nitrogen Fixation by Rhizobia and Extending the Scope to Cereals

MICROORGANISMS (2021)

Journal

MICROORGANISMS

Volume 9, Issue 1, Pages -

Publisher

MDPI

DOI: 10.3390/microorganisms9010125

Keywords

biological nitrogen fixation; efficiency; molecular biology; rhizobia; stress; ethylene; nodulation; improvement; cereals

Funding

Alberta Pulse Growers
Alberta Agriculture and Forestry [2019F003R]

Ask authors/readers for more resources

Protocol

Community support

Reagent

Community support

Automated Summary New
Abstract

The importance of biological nitrogen fixation has decreased with the widespread use of synthetic nitrogen fertilizers during the green revolution, due to their low cost and the lack of symbiotic associations with bacteria in staple crops. Recent advancements in symbiosis and nitrogen fixation, along with recombinant DNA technology, offer opportunities to increase symbiotically-driven nitrogen consumption globally.

The contribution of biological nitrogen fixation to the total N requirement of food and feed crops diminished in importance with the advent of synthetic N fertilizers, which fueled the green revolution. Despite being environmentally unfriendly, the synthetic versions gained prominence primarily due to their low cost, and the fact that most important staple crops never evolved symbiotic associations with bacteria. In the recent past, advances in our knowledge of symbiosis and nitrogen fixation and the development and application of recombinant DNA technology have created opportunities that could help increase the share of symbiotically-driven nitrogen in global consumption. With the availability of molecular biology tools, rapid improvements in symbiotic characteristics of rhizobial strains became possible. Further, the technology allowed probing the possibility of establishing a symbiotic dialogue between rhizobia and cereals. Because the evolutionary process did not forge a symbiotic relationship with the latter, the potential of molecular manipulations has been tested to incorporate a functional mechanism of nitrogen reduction independent of microbes. In this review, we discuss various strategies applied to improve rhizobial strains for higher nitrogen fixation efficiency, more competitiveness and enhanced fitness under unfavorable environments. The challenges and progress made towards nitrogen self-sufficiency of cereals are also reviewed. An approach to integrate the genetically modified elite rhizobia strains in crop production systems is highlighted.

Authors

I am an author on this paper

Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.6

Not enough ratings

Secondary Ratings

Novelty

Significance

Scientific rigor

Rate this paper

Adaptive Evolution of Rhizobial Symbiosis beyond Horizontal Gene Transfer: From Genome Innovation to Regulation Reconstruction

Sheng Liu, Jian Jiao, Chang-Fu Tian

Summary: There are variations in symbiotic performance of rhizobial strains associated with the same legume host in agriculture due to polymorphisms of symbiosis genes and unexplored variations in integration efficiency of symbiotic function. Experimental evolution and reverse genetic studies suggest that horizontal gene transfer of key symbiosis genes is necessary but insufficient for bacteria to establish an effective symbiosis. Further adaptive evolution and integration of accessory genes with the core network optimize symbiotic efficiency in various ecosystems and offer insights to develop elite rhizobial inoculants.

GENES (2023)