Biological nitrogen fixation in cereal crops: Progress, strategies, and perspectives

Guo, Kaiyan; Yang, Jun; Yu, Nan; Li, Luo; Wang, Ertao

doi:10.1016/j.xplc.2022.100499

Cited by 51 publications

(36 citation statements)

References 121 publications

(149 reference statements)

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“…Effective rhizobia bacteria have the potential to improve the yield and protein content of grain legumes (Murphy-Brokern et al, 2017;Allito et al, 2020), critical for the nearly one billion people worldwide who suffer from deficiencies in amino acids such as lysine, methionine and tryptophan, primarily in SubSaharan Africa and South Asia (Schönfeldt and Hall, 2012;Food Security Information Network, 2022). By enhancing biological nitrogen fixation, effective rhizobia can also reduce the usage of synthetic nitrogen fertilizer which consumes natural gas and contributes to climate change (Guo et al, 2022). Rhizobia can deliver fixed nitrogen directly inside plants, bypassing leaching associated with chemical fertilizers, which is especially problematic on the sandy soils prevalent in the African subtropic (Syers et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

Improving field legume nodulation by crushing nodules onto seeds: implications for small-scale farmers

2023

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One billion people globally suffer from protein (amino acid) malnutrition. Grain legumes represent a solution. They recruit symbiotic rhizobia bacteria from soil into root nodules, where the rhizobia convert atmospheric nitrogen gas (N2) into ammonia (NH3) which serves as a building block for chlorophyll and protein. However, when a legume species is newly introduced to a region, yields can be low due to incompatible soil rhizobia. Millions of subsistence legume farmers can benefit from inoculation with exotic rhizobia bacteria, but many subsistence farmers especially in Africa do not benefit from commercial inoculants due to real-world constraints. Here, in a sequential series of indoor and outdoor experiments, we show that root nodules (rhizobia habitats) can be harvested and crushed onto legume seeds, ultimately improving nodulation and chlorophyll under field conditions. 16S rRNA metagenomic sequencing confirmed that nodule crushing onto seeds effectively transferred rhizobia to next-generation nodules. Therefore, nodule crushing represents a simple method to diffuse elite rhizobia strains. However, exotic rhizobia come with risks and limitations. Therefore, in addition to diffusing elite rhizobia, we propose that this simple, decentralized technology can also empower smallholders to improve indigenous strains or indigenize exotic strains by repeated nodule crushing from healthy plants.

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Section: Discussionmentioning

confidence: 99%

Improving field legume nodulation by crushing nodules onto seeds: implications for small-scale farmers

2023

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“…N‐fixing bacteria in the rhizosphere of cereal crops and endophytic N‐fixing bacteria use plant photosynthetic products in root exudates as carbon sources to fix N (Guo et al ., 2023). The plants in turn benefit from the enhanced nitrogen in their rhizospheres, a relationship referred to as associative N fixation.…”

Section: Nitrogen Uptake and Regulationmentioning

confidence: 99%

Microbe‐dependent and independent nitrogen and phosphate acquisition and regulation in plants

Zhao,

Jia,

et al. 2023

New Phytologist

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SummaryNitrogen (N) and phosphorus (P) are the most important macronutrients required for plant growth and development. To cope with the limited and uneven distribution of N and P in complicated soil environments, plants have evolved intricate molecular strategies to improve nutrient acquisition that involve adaptive root development, production of root exudates, and the assistance of microbes. Recently, great advances have been made in understanding the regulation of N and P uptake and utilization and how plants balance the direct uptake of nutrients from the soil with the nutrient acquisition from beneficial microbes such as arbuscular mycorrhiza. Here, we summarize the major advances in these areas and highlight plant responses to changes in nutrient availability in the external environment through local and systemic signals.

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“…The symbiotic nitrogen-fixing microbiota can establish symbiotic relationships with plants and is the most effective means of biological nitrogen fixation. 15 Biological nitrogen fixation requires nitrogenase catalysis, of which there are three types: Mo−Fe, Fe−Fe, and V−Fe nitrogenases.…”

Section: Introductionmentioning

confidence: 99%

“…According to the relationships between nitrogen-fixing microbes and host plants, these microorganisms are primarily divided into three categories: symbiotic N fixers, free-living N fixers, and associative N fixers. The symbiotic nitrogen-fixing microbiota can establish symbiotic relationships with plants and is the most effective means of biological nitrogen fixation . Biological nitrogen fixation requires nitrogenase catalysis, of which there are three types: Mo–Fe, Fe–Fe, and V–Fe nitrogenases.…”

Section: Introductionmentioning

confidence: 99%

Deciphering Microbial Community and Nitrogen Fixation in the Legume Rhizosphere

Yang,

Xu,

Zhang

et al. 2024

J. Agric. Food Chem.

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Nitrogen is the most limiting factor in crop production. Legumes establish a symbiotic relationship with rhizobia and enhance nitrogen fixation. We analyzed 1,624 rhizosphere 16S rRNA gene samples and 113 rhizosphere metagenomic samples from three typical legumes and three non-legumes. The rhizosphere microbial community of the legumes had low diversity and was enriched with nitrogen-cycling bacteria (Sphingomonadaceae, Xanthobacteraceae, Rhizobiaceae, and Bacillaceae). Furthermore, the rhizosphere microbiota of legumes exhibited a high abundance of nitrogen-fixing genes, reflecting a stronger nitrogen-fixing potential, and Streptomycetaceae and Nocardioidaceae were the predominant nitrogen-fixing bacteria. We also identified helper bacteria and confirmed through metadata analysis and a pot experiment that the synthesis of riboflavin by helper bacteria is the key factor in promoting nitrogen fixation. Our study emphasizes that the construction of synthetic communities of nitrogen-fixing bacteria and helper bacteria is crucial for the development of efficient nitrogen-fixing microbial fertilizers.

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Biological nitrogen fixation in cereal crops: Progress, strategies, and perspectives

Cited by 51 publications

References 121 publications

Improving field legume nodulation by crushing nodules onto seeds: implications for small-scale farmers

Improving field legume nodulation by crushing nodules onto seeds: implications for small-scale farmers

Microbe‐dependent and independent nitrogen and phosphate acquisition and regulation in plants

Deciphering Microbial Community and Nitrogen Fixation in the Legume Rhizosphere

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