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Plant nitrogen nutrition: The roles of arbuscular mycorrhizal fungi.
Xie, K, Ren, Y, Chen, A, Yang, C, Zheng, Q, Chen, J, Wang, D, Li, Y, Hu, S, Xu, G
Journal of plant physiology. 2022;:153591
Abstract
Nitrogen (N) is the most abundant mineral nutrient required by plants, and crop productivity depends heavily on N fertilization in many soils. Production and application of N fertilizers consume huge amounts of energy and substantially increase the costs of agricultural production. Excess N compounds released from agricultural systems are also detrimental to the environment. Thus, increasing plant N uptake efficiency is essential for the development of sustainable agriculture. Arbuscular mycorrhizal (AM) fungi are beneficial symbionts of most terrestrial plants that facilitate plant nutrient uptake and increase host resistance to diverse environmental stresses. AM association is an endosymbiotic process that relies on the differentiation of both host plant roots and AM fungi to create novel contact interfaces within the cells of plant roots. AM plants have two pathways for nutrient uptake: either direct uptake via the root hairs and root epidermis, or indirectly through AM fungal hyphae into root cortical cells. Over the last few years, great progress has been made in deciphering the molecular mechanisms underlying the AM-mediated modulation of nutrient uptake processes, and a growing number of fungal and plant genes responsible for the uptake of nutrients from soil or transfer across the fungi-root interface have been identified. Here, we mainly summarize the recent advances in N uptake, assimilation, and translocation in AM symbiosis, and also discuss how N interplays with C and P in modulating AM development, as well as the synergies between AM fungi and soil microbial communities in N uptake.
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Molecular Regulatory Networks for Improving Nitrogen Use Efficiency in Rice.
Hou, M, Yu, M, Li, Z, Ai, Z, Chen, J
International journal of molecular sciences. 2021;(16)
Abstract
Nitrogen is an important factor limiting the growth and yield of rice. However, the excessive application of nitrogen will lead to water eutrophication and economic costs. To create rice varieties with high nitrogen use efficiency (NUE) has always been an arduous task in rice breeding. The processes for improving NUE include nitrogen uptake, nitrogen transport from root to shoot, nitrogen assimilation, and nitrogen redistribution, with each step being indispensable to the improvement of NUE. Here, we summarize the effects of absorption, transport, and metabolism of nitrate, ammonium, and amino acids on NUE, as well as the role of hormones in improving rice NUE. Our discussion provide insight for further research in the future.
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Transport properties and regulatory roles of nitrogen in arbuscular mycorrhizal symbiosis.
Chen, A, Gu, M, Wang, S, Chen, J, Xu, G
Seminars in cell & developmental biology. 2018;:80-88
Abstract
Many terrestrial plants can form root symbiosis with beneficial microorganisms for enhancing uptake of mineral nutrients or increasing fitness to adverse environmental challenges. Arbuscular mycorrhizal (AM) symbiosis that is formed by AM fungi and the roots of vascular flowering plants is the most widespread mutualistic associations in nature. As a typical endosymbiosis, AM interactions involves the differentiation of both symbionts to create novel symbiotic interfaces within the root cells, and requires a continuous nutrient exchange between the two partners. AM plants have two pathways for nutrient uptake, either direct uptake via the root hairs and root epidermis at the plant-soil interface, or indirectly through the AM fungal hyphae at the plant-fungus interface. Over the last few years, great progress has been made in deciphering the mechanisms underlying the AM-mediated modulation of nutrient uptake processes, and an increasing number of plant and fungal genes responsible for transporting nutrients from the soil or across the intraradical symbiotic interfaces have been identified and functionally characterized. Here, we summarize the recent advances in the nitrogen uptake, assimilation and translocation in the AM symbiosis, and also explore the current understanding of how the N status and interplay with C and P in modulating the development of AM associations.
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Regulation of Sensing, Transportation, and Catabolism of Nitrogen Sources in Saccharomyces cerevisiae.
Zhang, W, Du, G, Zhou, J, Chen, J
Microbiology and molecular biology reviews : MMBR. 2018;(1)
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Abstract
Nitrogen is one of the most important essential nutrient sources for biogenic activities. Regulation of nitrogen metabolism in microorganisms is complicated and elaborate. For this review, the yeast Saccharomyces cerevisiae was chosen to demonstrate the regulatory mechanism of nitrogen metabolism because of its relative clear genetic background. Current opinions on the regulation processes of nitrogen metabolism in S. cerevisiae, including nitrogen sensing, transport, and catabolism, are systematically reviewed. Two major upstream signaling pathways, the Ssy1-Ptr3-Ssy5 sensor system and the target of rapamycin pathway, which are responsible for sensing extracellular and intracellular nitrogen, respectively, are discussed. The ubiquitination of nitrogen transporters, which is the most general and efficient means for controlling nitrogen transport, is also summarized. The following metabolic step, nitrogen catabolism, is demonstrated at two levels: the transcriptional regulation process related to GATA transcriptional factors and the translational regulation process related to the general amino acid control pathway. The interplay between nitrogen regulation and carbon regulation is also discussed. As a model system, understanding the meticulous process by which nitrogen metabolism is regulated in S. cerevisiae not only could facilitate research on global regulation mechanisms and yeast metabolic engineering but also could provide important insights and inspiration for future studies of other common microorganisms and higher eukaryotic cells.
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Ecological characteristics of anaerobic ammonia oxidizing bacteria.
Ding, S, Zheng, P, Lu, H, Chen, J, Mahmood, Q, Abbas, G
Applied microbiology and biotechnology. 2013;(5):1841-9
Abstract
Anaerobic ammonium oxidation (anammox) is the microbial conversion of ammonium and nitrite to dinitrogen gas. The functional microbes of anammox reaction are anammox bacteria, which were discovered in a wastewater treatment system for nitrogen removal. Anammox bacteria are prevalent in anoxic ecosystems and play an important role in both biological nitrogen cycle and nitrogen pollution control. In this paper, we reviewed the investigation on ecological characteristics of anammox bacteria, and tried to figure out their complicated intraspecies and interspecies relationships. As for intraspecies relationship, we focused on the quorum sensing system, a cell density-dependent phenomenon. As for interspecies relationship, we focused on the synergism and competition of anammox bacteria with other microorganisms for substrate and space. Finally, we discussed the great influence of environmental factors (e.g., dissolved oxygen, organic matters) on the constitution, structure and function of anammox bacteria community.