Journal articles: 'Nitrogen-fixing plants'

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Good, Allen. "Toward nitrogen-fixing plants." Science 359, no. 6378 (February 22, 2018): 869–70. http://dx.doi.org/10.1126/science.aas8737.

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Li-Na, WANG, YU Yong-Qiang, LU Dong-Xu, and TANG Ya-Kun. "Soil pH modulates nitrogen transfer from nitrogen-fixing plants to non-nitrogen-fixing plants." Chinese Journal of Plant Ecology 46, no. 1 (2022): 1–17. http://dx.doi.org/10.17521/cjpe.2021.0283.

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Fahrenkamp-Uppenbrink, Julia. "Can scientists create nitrogen-fixing plants?" Science 359, no. 6378 (February 22, 2018): 880.18–882. http://dx.doi.org/10.1126/science.359.6378.880-r.

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THOMPSON, VINTON. "Spittlebug indicators of nitrogen-fixing plants." Ecological Entomology 19, no. 4 (November 1994): 391–98. http://dx.doi.org/10.1111/j.1365-2311.1994.tb00257.x.

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Liang, Yueming, Xunyang He, Xiangbi Chen, Yirong Su, Fujing Pan, and Lening Hu. "Low Frequency of Plants Associated with Symbiotic Nitrogen-Fixers Exhibits High Frequency of Free-Living Nitrogen Fixing Bacteria: A Study in Karst Shrub Ecosystems of Southwest China." Forests 13, no. 2 (January 21, 2022): 163. http://dx.doi.org/10.3390/f13020163.

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Plants associated with symbiotic nitrogen-fixers and soil free-living nitrogen-fixing bacteria are good indicators for detecting the source of nitrogen in natural ecosystems. However, the community composition and diversity of plants associated with symbiotic nitrogen-fixers and soil free-living nitrogen-fixing bacteria in karst shrub ecosystems remain poorly known. The community composition and diversity of soil free-living nitrogen-fixing bacteria and plants, as well as the soil physical–chemical properties were investigated in 21 shrub plots (including different topographies and plant types). The frequency of plants associated with symbiotic nitrogen-fixers was found to be low in the 21 shrub plots. The soil free-living nitrogen-fixing bacterial community structure varied among the 21 shrub soils. Based on a variance partitioning analysis, topography, plant type, and soil pH explained 48.5% of the observed variation in bacterial community structure. Plant type had a predominant effect on community structure, and topography (aspect and ascent) and soil pH had minor effects. A negative correlation between the abundance of the soil free-living nitrogen-fixing bacterial community and the richness index for plants associated with symbiotic nitrogen-fixers was observed. The result of the low frequency of plants associated with symbiotic nitrogen-fixers highlights the importance of sources of fixed nitrogen by soil free-living nitrogen-fixing bacteria in the nitrogen limitation shrub ecosystem of the karst regions.

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Chen, Haoran, Sylvie Renault, and John Markham. "The Effect of Frankia and Hebeloma crustiliniforme on Alnus alnobetula subsp. Crispa Growing in Saline Soil." Plants 11, no. 14 (July 16, 2022): 1860. http://dx.doi.org/10.3390/plants11141860.

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The mining of the oil sands region of Canada’s boreal forest creates disturbed land with elevated levels of salts. Understanding how native plants respond to salt stress is critical in reclaiming these lands. The native species, Alnus alnobetula subsp. crispa forms nitrogen-fixing nodules with Frankia, and ectomycorrhizae with a number of fungal species. These relationships may make the plant particularly well suited for restoring disturbed land. We inoculated A. alnobetula subsp. crispa with Frankia and Hebeloma crustiliniforme and exposed the plants to 0, 50, or 100 mM NaCl for seven weeks. Frankia-inoculated plants had increased biomass regardless of salt exposure, even though salt exposure reduced nitrogen fixation and reduced the efficiency of nitrogen-fixing nodules. The nitrogen-fixing symbiosis also decreased leaf stress and increased root phosphatase levels. This suggests that N-fixing plants not only have increased nitrogen nutrition but also have increased access to soil phosphorus. Mycorrhizae did not affect plant growth but did reduce nodule numbers and nodule efficiency. These results suggest that the nitrogen-fixing trait is more critical than mycorrhizae. While salt stress inhibits nitrogen-fixing symbiosis, plants still benefit from nitrogen fixation when exposed to salt.

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Mohr, Wiebke, Nadine Lehnen, Soeren Ahmerkamp, Hannah K. Marchant, Jon S. Graf, Bernhard Tschitschko, Pelin Yilmaz, et al. "Terrestrial-type nitrogen-fixing symbiosis between seagrass and a marine bacterium." Nature 600, no. 7887 (November 3, 2021): 105–9. http://dx.doi.org/10.1038/s41586-021-04063-4.

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AbstractSymbiotic N2-fixing microorganisms have a crucial role in the assimilation of nitrogen by eukaryotes in nitrogen-limited environments1–3. Particularly among land plants, N2-fixing symbionts occur in a variety of distantly related plant lineages and often involve an intimate association between host and symbiont2,4. Descriptions of such intimate symbioses are lacking for seagrasses, which evolved around 100 million years ago from terrestrial flowering plants that migrated back to the sea5. Here we describe an N2-fixing symbiont, ‘Candidatus Celerinatantimonas neptuna’, that lives inside seagrass root tissue, where it provides ammonia and amino acids to its host in exchange for sugars. As such, this symbiosis is reminiscent of terrestrial N2-fixing plant symbioses. The symbiosis between Ca. C. neptuna and its host Posidonia oceanica enables highly productive seagrass meadows to thrive in the nitrogen-limited Mediterranean Sea. Relatives of Ca. C. neptuna occur worldwide in coastal ecosystems, in which they may form similar symbioses with other seagrasses and saltmarsh plants. Just like N2-fixing microorganisms might have aided the colonization of nitrogen-poor soils by early land plants6, the ancestors of Ca. C. neptuna and its relatives probably enabled flowering plants to invade nitrogen-poor marine habitats, where they formed extremely efficient blue carbon ecosystems7.

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AKAO, Shoichiro, Tadashi YOKOYAMA, and Tadakatsu YONEYAMA. "Communication between Nitrogen-fixing Microbes and Plants." JOURNAL OF THE BREWING SOCIETY OF JAPAN 89, no. 5 (1994): 341–48. http://dx.doi.org/10.6013/jbrewsocjapan1988.89.341.

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Meeks, John C. "Symbiosis between Nitrogen-Fixing Cyanobacteria and Plants." BioScience 48, no. 4 (April 1998): 266–76. http://dx.doi.org/10.2307/1313353.

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Ekowati, Cristina Nugroho, Mica Mirani, Kusuma Handayani, and Rochmah Agustrina. "DETECTION OF NITROGENASE PRODUCING BACTERIA FROM THE SOIL OF LIWA BOTANICAL GARDEN." Jurnal Ilmiah Biologi Eksperimen dan Keanekaragaman Hayati (J-BEKH) 8, no. 2 (December 30, 2021): 53–58. http://dx.doi.org/10.23960/jbekh.v8i2.204.

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Liwa Botanical Gardens is an ex-situ conservation area for various types of plants. Each plant produces organic matter that will provide nutrients for the growth of nitrogen-fixing bacteria. This indicates the existence of an environment that supports the growth of nitrogen-fixing bacteria. Nitrogen is one of the nutrients needed by plants for their growth. However, the abundance of nitrogen in the atmosphere cannot be utilized directly by plants but needs to transform into ammonium and nitrate first. This transformation can be done by nitrogen-fixing bacteria through an enzymatic process. This research aims to obtain bacterial isolates that can fix nitrogen. Nitrogen-fixing bacteria were isolated using Nutrient Agar (NA) medium and furthered by nitrogenase activity detection test with semi-solid Nitrogen Free Bromothymol Blue (NFB). Nitrogen-fixing bacteria are characterized by color changes in the medium. The results obtained 22 isolates with 3 isolates detected capable of producing nitrogenase enzymes, namely TBP B3, TB1 B2, and TMA2 B2.

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Anggrainy, Eka Dewi, Arifah Hidayati, Roby Ibnu Syarifain, Muhammad Faizal Rezha Zulkarnain, and Tualar Simarmata. "Superior Nitrogen Fixing Bacteria Screening from Various Rhizobiome in Palm Oil Plantion, North Sangatta, East Kalimantan." IOP Conference Series: Earth and Environmental Science 748, no. 1 (April 1, 2021): 012007. http://dx.doi.org/10.1088/1755-1315/748/1/012007.

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Abstract Nitrogen fixing bacteria (NFB) plays an important role in increasing N availability for plants. Research to examine the ability of nitrogen fixing bacteria isolates to produce nitrogenase, phytohormone and the ability of nitrogen fixing bacteria isolates in the biological test process using the corn plant indicator as an indicator has been carried out from September 2018 to February 2019 in laboratories and greenhouses. The ability of nitrogen fixing bacteria was tested by the ARA method, while the phytohormone testing of nitrogen fixing bacteria was tested using the HPLC method. Bioassays using Murphy media and corn plants as indicators were performed using a randomized block design consisting of six treatments (one control and five selected NFB isolates from the selection results) and given five replications. Measurement of root length, plant height, and dry weight of plants were carried out every 2 days for 14 days. The results showed that the nitrogen fixing bacteria isolates used from North Sangattarhizobiome, East Kalimantan had different nitrogenase and differentphytohormone test results, and obtained five selected isolates based on the selection results. The results of the bioassay did not show any significant differences based on the Duncan test at the level of 5%. However, it can be seen visually the significant difference in which plants in the biological test using nitrogen fixing bacterial isolates have relatively higher plant growth and dry weight of plants than plants that are not given treatment or control.

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Kirova, E., D. Nedeva, A. Nikolova, and G. Ignatov. "Changes in the electrophoretic spectra of antioxidant enzymes in nitrate-fed and nitrogen-fixing soybean subjected to gradual water stress." Acta Agronomica Hungarica 52, no. 4 (March 1, 2005): 323–32. http://dx.doi.org/10.1556/aagr.52.2004.4.1.

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The effect of two sources of nitrogen (nitrogen fixation or nitrate assimilation) and gradual water stress on theelectrophoretic spectra of peroxidase, catalase and superoxide dismutase was studied in soybean leaves. An increase in H2O2 production was observed, especially after the prolonged drought treatment. At 50% drought the activity of anionic peroxidase activity for isoenzymes Nos. 2 and 7+8 significantly increased (by 54 and 18%, respectively) in the leaves of nitrate-fed plants compared to the control plants; for nitrogen-fixing plants these values were 31 and 14%, respectively. In the case of cationic peroxidases, the application of 50% drought led to the inhibition of the moderately fast isoenzymes (Nos. 2 and 3, with Rm 0.5 and 0.65, respectively) and the activation of the fastest moving isoenzyme (No. 4, with Rm 0.8) in nitrate-fed soybean. The same tendency was observed in the leaves of nitrogen-fixing plants. The effect of restricted soil humidity on SOD activity was expressed as a change in the activity of some of the isoenzymes. There was a clear tendency for the SOD isoenzyme activity to increase after the exposure of nitrate-fed and nitrogen-fixing soybean plants to 50% drought treatment. high catalase activity was registered in control nitrate-fed plants. Generally the catalase isoenzyme activity in control nitrogen-fixing plants had low values. Both intensities of water stress (30 and 50% drought) caused an increase in the catalase activity, and this increase was much higher for nitrogen-fixing plants. Therefore, soybean plants responded to drought treatment by changes in the antioxidant enzyme activity, as these changes were partially dependent on the source of nitrogen. The results suggested that nitrogen-fixing soybean plants were more resistant to gradual water stress.

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Markham, John H. "Does Dryas integrifolia fix nitrogen?" Botany 87, no. 11 (November 2009): 1106–9. http://dx.doi.org/10.1139/b09-071.

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Symbiotic nitrogen fixation is found in plant taxa that also include non-nitrogen-fixing members. Strong evidence for the occurrence of nitrogen fixation comes from physiological measurements and the identification of the nitrogen fixing symbiont. This evidence has been provided for Dryas drummondii Richardson ex Hook. in the Rosaceae. However, while there have been numerous references to the nitrogen fixing ability of Dryas integrifolia Vahl., they can all be traced to a single report that did not provide strong evidence for nitrogen fixation. My attempts to establish nitrogen fixing nodules on vegetatively propagated plants from the field, or seedlings of D. integrifolia, using three different sources of Frankia , all failed. Since other host plants ( Alnus viridis (Chaix) DC. subsp. crispa (Aiton) Turrill and Purshia tridentata (Pursh.) DC.) did produce nitrogen-fixing nodules under the same growth conditions, the ability of D. integrifolia to fix nitrogen should be considered suspect.

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Sprent, J. I., and J. A. Raven. "Evolution of nitrogen-fixing symbioses." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 85, no. 3-4 (1985): 215–37. http://dx.doi.org/10.1017/s0269727000004036.

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SynopsisBecause of both the energy costs and the slowness of the reactions of the nitrogenase complex compared with those involving some form of combined nitrogen (oxidised or reduced), we argue that the evolution of nitrogen-fixing organisms required an environment which was very limited in combined nitrogen. This is thought to have occurred after phototrophy evolved, but before water was used as a hydrogen donor (and therefore oxygen was present in the atmosphere). After oxygenic photosynthesis evolved, the need for a high level of biological nitrogen-fixation remained, since abiotic inputs were insufficient to keep pace with the rapidly evolving biomass (flora and fauna). Symbiotic fixation probably first evolved in the form of casual associations between cyanobacteria and most other groups of plants. By inhabiting the sporophytic generation of evolving land plants (cycads in particular), protection against nitrogenase-inactivating oxygen and a more desiccating environment was achieved simultaneously.We envisage nodulated plants arising by the transfer ofnifgenes into tumour-forming bacteria. In the case of legumes, these would be ancestors of extant agrobacteria, which gain entry into their hostsviawounds. Co-evolution of symbionts from nitrogen-fixing tumours has taken several routes, leading to extant nodules differing in mode of infection, structure and physiology. Evolution towards optimisation of oxygen usage is continuing.Nitrogen-fixing symbiosis in animal systems is only advantageous in specialised ecological niches in which wood is the sole dietary intake. In the case of shipworms, the symbiosis has many of the advanced features associated with nitrogen fixing root nodules.

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Sa, T‐M, and D. W. Israel. "Nitrogen Assimilation in Nitrogen‐Fixing Soybean Plants during Phosphorus Deficiency." Crop Science 35, no. 3 (May 1995): 814–20. http://dx.doi.org/10.2135/cropsci1995.0011183x003500030030x.

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Chen, Haoran, and John Markham. "The Interactive Effect of Elevated CO2 and Herbivores on the Nitrogen-Fixing Plant Alnus incana ssp. rugosa." Plants 10, no. 3 (February 26, 2021): 440. http://dx.doi.org/10.3390/plants10030440.

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Many studies have found that future predicted CO2 levels can increase plant mass but dilute N content in leaves, impacting antiherbivore compounds. Nitrogen-fixing plants may balance their leaf C:N ratio under elevated CO2, counteracting this dilution effect. However, we know little of how plants respond to herbivores at the higher CO2 levels that occurred when nitrogen-fixing plants first evolved. We grew Alnus incana ssp. rugosa was grown at 400, 800, or 1600 ppm CO2 in soil collected from the field, inoculated with Frankia and exposed to herbivores (Orgyia leucostigma). Elevated CO2 increased nodulated plant biomass and stimulated the nitrogen fixation rate in the early growth stage. However, nitrogen-fixing plants were not able to balance their C:N ratio under elevated CO2 after growing for 19 weeks. When plants were grown at 400 and 1600 ppm CO2, herbivores preferred to feed on leaves of nodulated plants. At 800 ppm CO2, nodulated plants accumulated more total phenolic compounds in response to herbivore damage than plants in the non-Frankia and non-herbivore treatments. Our results suggest that plant leaf defence, not leaf nutritional content, is the dominant driver of herbivory and nitrogen-fixing plants have limited ability to balance C:N ratios at elevated CO2 in natural soil.

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Gunawan, Agung, Yusminah Hala, Alimuddin Ali, Oslan Jumadi, and Muhammad Junda. "Vegetative growth response of upland rice to Actinomycetes, Azospirillum and Azotobacter." IOP Conference Series: Earth and Environmental Science 911, no. 1 (November 1, 2021): 012060. http://dx.doi.org/10.1088/1755-1315/911/1/012060.

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Abstract The research aims is to determine the suitability of nitrogen fixing bacteria, namely Actinomycetes, Azospirillum and Azotobacter with upland rice seeds to the speed of radicle formation and growth of upland rice plants. Upland rice plant growth measurement parameters include; speed of formation of radicle length, upland rice plant height, number of upland rice tillers, dry weight of the top of upland rice plants and roots of upland rice plants, wet weight of upland rice plants and roots of upland rice plants, and total N of upland rice plants and upland roots Testing the application of N2 fixing bacteria on upland rice plants on a laboratory scale was carried out to determine the suitability of microbes with upland rice plant seeds in vitro. The pot test was carried out to determine the suitability of the N2 fixing bacteria with the vegetative growth of upland rice plants in vivo. Data were analyzed using ANOVA with Duncan’s advanced test. The results showed that upland rice plants inoculated with Actinomycetes, Azospirillum and Azotobacter showed significantly different growth from upland rice plants without nitrogen fixing bacteria treatment, namely the radicle formation speed and radicle length, plant height, number of tillers, wet weight, dry weight, and total N (%) plants. It can be concluded that the inoculation of nitrogen-fixing bacteria on upland rice plants has a significant effect on plant vegetative growth parameters and plant nitrogen content.

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Fallo, Gergonius, Anastasia Buak, and Lukas Pardosi. "SELEKSI Seleksi Dan Identifikasi Bakteri Penambat Nitrogen Pada Perakaran Tanaman Kacang Hijau (Vigna radiata L) Dan Tomat (Solanum lycopersicum L) Di Kabupaten Belu." Jurnal Biologi dan Pembelajarannya (JB&P) 9, no. 1 (April 22, 2022): 34–41. http://dx.doi.org/10.29407/jbp.v9i1.17751.

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Nitrogen fixing bacteria are often called diazotroph bacteria which are able to use air nitrogen as a nitrogen source for their growth. Nitrogen fixing bacteria have the ability to increase the efficiency of N- available in the soil. The purpose of this study was to determine the morphological and biochemical characters of nitrogen-fixing bacteria from the roots of mung bean and tomato plants in Belu Regency. Isolation of nitrogen fixing bacteria by scratch method and spread on NA media. While the selection of nitrogen fixing bacteria using Jensen agar media. The results of the isolation obtained 12 isolates. Six isolates from roots of tomato plants and six isolates from roots of mung bean plants. The morphological characters of the 12 isolates were generally round in shape, small in size, flat in elevation and milky white in color. The selection results showed that 3 isolates grew on Jansen agar media, namely RKHB05, RKHB06, and RTB06. The result of gram staining showed that RKHB05, RKHB06 isolates were gram negative and had cocci cell form, while RTB06 isolates were gram positive with bacillus cell forms. The 3 isolates were positive for motility test, Citrate test, TSIA, and Catalase test

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Rahmani, Tara Puri Ducha. "Simple Feasibility Analysis Of Nitrogen-Fixing Cereals Project." Al-Hayat: Journal of Biology and Applied Biology 3, no. 2 (December 8, 2020): 102. http://dx.doi.org/10.21580/ah.v3i2.6082.

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<p>Nitrogen does not directly have advantages in human physiology system, but it holds one of the most critical roles in plants’ life cycle and productivity. Even though Nitrogen is the most abundant elements in the atmosphere, it is also the most deficient essential nutrients in plants. The proposed idea of the nitrogen-fixing GM crops, particularly wheat, is aimed to overcome those stated cons of the traditional diculture and nitrogen fertilizer. This analysis focus on the overview as well as the pro and cons of the genetically modified nitrogen-fixing plants in providing a better agricultural method. The genetically modifying method to generate a nitrogen-fixing non-legumes carries a significant chance of failure results and hindrance. The multilevel implication occurs when we need to modify the plants that not normally produce nodules in their roots to form the nodules and to modify the Nitrogen-fixing microbes to live in the nodules of non-legumes, which are not their natural dwelling places.</p><p>In conclusion, the genetically modified crops project to fix their Nitrogen is feasible, but the difficulties and the funds needed still outweigh the benefits obtained in the future. With all of those limitations, the target goal to erase famine in 2050 just by funding the nitrogen-fixing wheat alone seems to be too high to be reached. The funds and efforts should be better spent on other factors and farming methods.</p>

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Kirova, E., D. Nedeva, A. Nikolova, and G. Ignatov. "Changes in the biomass production and total soluble protein spectra of nitrate-fed and nitrogen-fixing soybeans subjected to gradual water stress." Plant, Soil and Environment 51, No. 5 (November 19, 2011): 237–42. http://dx.doi.org/10.17221/3580-pse.

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The effect of the sources of nitrogen nutrition (nitrogen fixation or nitrate assimilation) and a gradual water stress on the relative water content, total fresh and dry biomass production, leaf growth, and changes in the total soluble protein spectra were studied. The plants were cultivated as soil cultures in a naturally illuminated greenhouse. Comparative studies were carried out with respect to well-watered, control plants. Nitrogen-fixing control and drought plants had relatively smaller root development but better relative water content and large leaf area on the last sampling day than nitrate-fed soybean plants. Water deficit effects on plant biomass at the end of the period studied (21 days) were independent on the nitrogen source. There was no qualitative difference in the total soluble protein spectra of nitratefed and nitrogen-fixing soybean leaves neither with the progress of development nor under drought conditions. But there was a difference in response to drought in termostable proteins of nitrate-fed and nitrogen-fixing plants. The quantity of termostable proteins in inoculated control plants was lower in some degree compared to uninoculated ones. In inoculated plants the water stress caused an increase in the amount of soluble termostable proteins

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Minamisawa, Kiwamu, Kiyo Nishioka, Taro Miyaki, Bin Ye, Takuya Miyamoto, Mu You, Asami Saito, et al. "Anaerobic Nitrogen-Fixing Consortia Consisting of Clostridia Isolated from Gramineous Plants." Applied and Environmental Microbiology 70, no. 5 (May 2004): 3096–102. http://dx.doi.org/10.1128/aem.70.5.3096-3102.2004.

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ABSTRACT We report here the existence of anaerobic nitrogen-fixing consortia (ANFICOs) consisting of N2-fixing clostridia and diverse nondiazotrophic bacteria in nonleguminous plants; we found these ANFICOs while attempting to overcome a problem with culturing nitrogen-fixing microbes from various gramineous plants. A major feature of ANFICOs is that N2 fixation by the anaerobic clostridia is supported by the elimination of oxygen by the accompanying bacteria in the culture. In a few ANFICOs, nondiazotrophic bacteria specifically induced nitrogen fixation of the clostridia in culture. ANFICOs are widespread in wild rice species and pioneer plants, which are able to grow in unfavorable locations. These results indicate that clostridia are naturally occurring endophytes in gramineous plants and that clostridial N2 fixation arises in association with nondiazotrophic endophytes.

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Dawson, Jeffrey O. "Actinorhizal Plants: Their Use in Forestry and Agriculture." Outlook on Agriculture 15, no. 4 (December 1986): 202–8. http://dx.doi.org/10.1177/003072708601500406.

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The increasing cost of synthetic fertilizers has stimulated interest in the nitrogen-fixing property of Rhizobium, particularly as genetic engineering techniques raise the possibility of a symbiotic relationship with cereals. By contrast, the similar root nodules formed by nitrogen-fixing actinomycetes of the genus Frankia have been relatively little studied. Yet, as this article shows, the actinorhizal plants have very considerable possibilities for the utilization of marginal lands, especially in developing countries.

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Asrul, Asrul, and I. Nyoman Pugeg Aryantha. "ISOLASI DAN IDENTIFIKASI BAKTERI PENAMBAT NITROGEN UNTUK PEMBUATAN BIOFERTILIZER." VIABEL: Jurnal Ilmiah Ilmu-Ilmu Pertanian 15, no. 1 (May 6, 2021): 16–23. http://dx.doi.org/10.35457/viabel.v15i1.1386.

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Nitrogen is a macro nutrient needed by plants. Generally, people use inorganic fertilizers to fulfill nitrogen nutrients in plants. The problem then is, the continuous use of synthetic nitrogen fertilizers has a direct negative impact on the soil and a derivative impact on human health. The use of microorganisms, in this case bacteria, to provide nitrogen to plants can be done by isolating it and making it a biological fertilizer agent. Nitrogen fixing bacteria was isolated on the land of the oil palm plantation of PT Astra Agro Lestari. The isolated nitrogen-fixing bacteria were then tested quantitatively for their ability to fix nitrogen. The bacteria with the highest nitrogen fixing ability were then identified by sequencing their DNA nucleotide bases so that the bacterial strains were identified. The result is that there are 13 bacteria that are able to fix nitrogen with the codes J1, J3, Q5, L1, L11, J31, D1, M6, M5, R1, P2, J4 and C7. The quantitative test shows that bacteria with code D1 are the best at fixing nitrogen in the form of NH4, namely 0.27 ppm. The results of D1 bacterial DNA nucleotide base sequencing showed that the putitive Bacillus aerius strain 24K with identical values and query cover reach

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Mahmud, Kishan, Shiva Makaju, Razi Ibrahim, and Ali Missaoui. "Current Progress in Nitrogen Fixing Plants and Microbiome Research." Plants 9, no. 1 (January 13, 2020): 97. http://dx.doi.org/10.3390/plants9010097.

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In agroecosystems, nitrogen is one of the major nutrients limiting plant growth. To meet the increased nitrogen demand in agriculture, synthetic fertilizers have been used extensively in the latter part of the twentieth century, which have led to environmental challenges such as nitrate pollution. Biological nitrogen fixation (BNF) in plants is an essential mechanism for sustainable agricultural production and healthy ecosystem functioning. BNF by legumes and associative, endosymbiotic, and endophytic nitrogen fixation in non-legumes play major roles in reducing the use of synthetic nitrogen fertilizer in agriculture, increased plant nutrient content, and soil health reclamation. This review discusses the process of nitrogen-fixation in plants, nodule formation, the genes involved in plant-rhizobia interaction, and nitrogen-fixing legume and non-legume plants. This review also elaborates on current research efforts involved in transferring nitrogen-fixing mechanisms from legumes to non-legumes, especially to economically important crops such as rice, maize, and wheat at the molecular level and relevant other techniques involving the manipulation of soil microbiome for plant benefits in the non-legume root environment.

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Zekveld, Corinthe, and John Markham. "Exposure to aphids increases alder growth and nitrogen fixation." Botany 89, no. 4 (April 2011): 255–61. http://dx.doi.org/10.1139/b11-012.

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Plants can respond to herbivore damage by mounting a resistance response or by compensating for lost fitness. Both plant nutrition and interactions with soil microbes can affect these responses. It has been shown that resistance responses can occur before plants have been attacked by herbivores. Here we show that a tolerance type of response can occur when plants are exposed to, but not fed on by, herbivores. Alnus viridis (Chaix) DC. spp. crispa (Ait.) Turrill were grown in sealed containers under positive air pressure with either 0.5 mmol·L–1 or 2.0 mmol·L–1 nitrate and either inoculated or not inoculated with Frankia , their nitrogen-fixing symbiont. Plants were then exposed to the genus-specific aphid Prociphilus tessallatus Fitch, which failed to establish feeding colonies. Exposure to aphids, formation of nitrogen-fixing nodules, and elevated soil nitrogen levels all significantly increased plant yield with no interaction among these factors. A combination of high soil nitrogen, nodulation, and exposure to aphids resulted in the lowest plant root:shoot ratio. Plants that were grown with low nitrogen and were exposed to aphids showed increased nitrogen-fixing activity within a day of being exposed. These results provide further evidence to support the observation that plants can respond to cues from other organisms prior to receiving herbivore damage.

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Markham, John H., and Corinthe Zekveld. "Nitrogen fixation makes biomass allocation to roots independent of soil nitrogen supply." Canadian Journal of Botany 85, no. 9 (September 2007): 787–93. http://dx.doi.org/10.1139/b07-075.

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Biomass allocation patterns in plants are known to be affected by soil nitrogen availability. Since nitrogen availability can depress symbiotic nitrogen fixation, and nitrogen fixation can make plant growth independent of soil nitrogen availability but is energetically costly, it is unclear how allocation patterns in nitrogen-fixing species should respond to variation in soil nitrogen availability. We examined the effect of nitrogen source and concentration on the growth and allocation patterns in the nitrogen-fixing shrub Alnus viridis subsp. crispa (Aiton) Turrill. Plants were grown with either NH4+-N or NO3–-N at a range of low N concentrations, from 0 to 2 mmol·L–1, and either inoculated with Frankia or not. Plants without nodules had 25.l% lower biomass and had double the allocation to roots at all but the 2 mmol·L–1 nitrogen concentration. Even though nodulated plants increased growth with nitrogen concentration, allocation to roots as a fraction of total biomass did not vary in these plants, suggesting increased growth resulted from more efficient nitrogen acquisition. Allocation to roots was a significant predictor of plant growth in non-nodulated plants (r2 = 0.318, for linear least squares fit with log mass) but not for nodulated plants (r2 = 0.108). As nitrogen concentrations increased, allocation to nodules, specific nodule numbers, and the proportion of nitrogen fixed by the plants decreased, demonstrating a shift to soil nitrogen use.

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Newland, J. A., and T. H. DeLuca. "Influence of fire on native nitrogen-fixing plants and soil nitrogen status in ponderosa pine - Douglas-fir forests in western Montana." Canadian Journal of Forest Research 30, no. 2 (February 15, 2000): 274–82. http://dx.doi.org/10.1139/x99-206.

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Nitrogen fixing plants have been reported to play an important role in replacing N lost from soil in fire dominated ecosystems. Exclusion of fire from ponderosa pine (Pinus ponderosa Dougl. ex Laws.) - Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests of western Montana has lead to widespread changes in forest structure, composition, and function including a potential reduction in the occurrence of N-fixing plant species. We investigated the effect of fire exclusion and reintroduction of fire on the frequency, occurrence, and function of native N-fixing plant species at 11 paired burned and unburned sites in western Montana. These pairs had been either undisturbed since the early 1900s or had been repeatedly opened by logging and (or) fire over the last 80-100 years. Although the percent cover of N-fixing plants was low at all sites, the cover and frequency of N-fixing plants were significantly greater in sites exposed to fire than in the unburned sites and greater in repeatedly opened sites than in undisturbed sites. In contrast, levels of available N were significantly lower in burned sites compared with unburned sites and in repeatedly opened sites. Nitrogen-fixing plants may have played an important role in maintaining productivity in frequently burned ponderosa pine forests but now appear to be suppressed in fire-excluded forests.

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Nadkernychna, O. V., and E. P. Kopylov. "NITROGEN FIXING BACTERIA OF SPRING WHEAT ROOT ZONE." Agriciltural microbiology 17 (October 1, 2013): 7–20. http://dx.doi.org/10.35868/1997-3004.17.7-20.

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The paper presents the study of active nitrogen fixation bacteria of genera Azotobacter, Azospirillum, Bacillus, Flavobacterium, Enterobacter and Pseudomonas isolated from root zone of spring wheat plants. The ability of selected diazotrophs to form associative systems with spring wheat was investigated. The most significant increase of molecular nitrogen fixation activity in root zone of plants was observed under the Azospirillum species background.

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Shelp, Barry J., and Robert J. Ireland. "Ureide Metabolism in Leaves of Nitrogen-Fixing Soybean Plants." Plant Physiology 77, no. 3 (March 1, 1985): 779–83. http://dx.doi.org/10.1104/pp.77.3.779.

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Carpena, Ramón O., Elvira Esteban, M. José Sarro, Jesús Peñalosa, Agustı́n Gárate, Juan J. Lucena, and Pilar Zornoza. "Boron and calcium distribution in nitrogen-fixing pea plants." Plant Science 151, no. 2 (February 2000): 163–70. http://dx.doi.org/10.1016/s0168-9452(99)00210-1.

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Sprent, J. I., and S. M. de Faria. "Mechanisms of infection of plants by nitrogen fixing organisms." Plant and Soil 110, no. 2 (August 1988): 157–65. http://dx.doi.org/10.1007/bf02226795.

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Daft, M. J., D. M. Clelland, and Isobel C. Gardner. "Symbiosis with endomycorrhizas and nitrogen-fixing organisms." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 85, no. 3-4 (1985): 283–98. http://dx.doi.org/10.1017/s0269727000004073.

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SynopsisInteractions amongst plants and different endophytes are prevalent in soils deficient in both nitrogen and phosphorus. Several systems are now recognised, combining infections by both fungi and prokaryotes. Symbiotic associations are ancient and reflect the requirements for the maximum uptake of nitrogen and phosphorus in plant nutrition.

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Bai, Lu, Yingming Yang, Ziyue Shi, Yiping Zou, Huixin Zhou, and Jianli Jia. "Improvement of Low-Fertility Soils from a Coal Mining Subsidence Area by Immobilized Nitrogen-Fixing Bacteria." Processes 10, no. 6 (June 14, 2022): 1185. http://dx.doi.org/10.3390/pr10061185.

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Coal mining subsidence leads to reductions in soil fertility. In order to improve soil physical and chemical properties and to promote vegetation restoration, a nitrogen-fixing bacterium named S1 was isolated from the coal mining subsidence area in the Shendong mining area, and a zeolite-immobilized nitrogen-fixing bacterium was studied to improve the soil in the subsidence area. The results show that the immobilized nitrogen-fixing bacteria can significantly improve the ammonium nitrogen and nitrate nitrogen of soil by 50 times and 0.6 times, respectively, at 20 days, and it can also improve organic matter. In pot experiments, it was found that immobilized microorganisms can improve germination rate, plant height and the dry and fresh weight of maize. The results of the above soil culture tests and pot experiments were then compared and analyzed. It was found that plants made obvious use of soil ammonium nitrogen and nitrate nitrogen, and planting the plants was conducive to increases in soil organic matter.

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Robledo, Marta, Natalia I. García-Tomsig, and José I. Jiménez-Zurdo. "Riboregulation in Nitrogen-Fixing Endosymbiotic Bacteria." Microorganisms 8, no. 3 (March 10, 2020): 384. http://dx.doi.org/10.3390/microorganisms8030384.

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Small non-coding RNAs (sRNAs) are ubiquitous components of bacterial adaptive regulatory networks underlying stress responses and chronic intracellular infection of eukaryotic hosts. Thus, sRNA-mediated regulation of gene expression is expected to play a major role in the establishment of mutualistic root nodule endosymbiosis between nitrogen-fixing rhizobia and legume plants. However, knowledge about this level of genetic regulation in this group of plant-interacting bacteria is still rather scarce. Here, we review insights into the rhizobial non-coding transcriptome and sRNA-mediated post-transcriptional regulation of symbiotic relevant traits such as nutrient uptake, cell cycle, quorum sensing, or nodule development. We provide details about the transcriptional control and protein-assisted activity mechanisms of the functionally characterized sRNAs involved in these processes. Finally, we discuss the forthcoming research on riboregulation in legume symbionts.

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Puente, Maria-Esther, and Yoav Bashan. "The desert epiphyte Tillandsia recurvata harbours the nitrogen-fixing bacterium Pseudomonas stutzeri." Canadian Journal of Botany 72, no. 3 (March 1, 1994): 406–8. http://dx.doi.org/10.1139/b94-054.

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Pseudomonas stutzeri, a nitrogen-fixing bacterium, was isolated from the interior of the desert epiphyte Tillandsia recurvata, which grows on electrical cables and giant columnar cacti in the semiarid zone of Baja California, Mexico. This study is the first to indicate the possible close association between bromeliad plants and nitrogen-fixing bacteria. Key words: beneficial bacteria, bromeliads, Bromeliaceae, nitrogen fixation, Pseudomonas stutzeri, Tillandsia recurvata.

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Iniguez, A. Leonardo, Yuemei Dong, and Eric W. Triplett. "Nitrogen Fixation in Wheat Provided by Klebsiella pneumoniae 342." Molecular Plant-Microbe Interactions® 17, no. 10 (October 2004): 1078–85. http://dx.doi.org/10.1094/mpmi.2004.17.10.1078.

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In this report, all of the criteria necessary for the demonstration of nitrogen fixation in wheat (Triticum aestivum L.), the world's most important crop, are shown upon inoculation with a nitrogen-fixing bacterium, Klebsiella pneumoniae 342 (Kp342). Kp342 relieved nitrogen (N) deficiency symptoms and increased total N and N concentration in the plant. Nitrogen fixation was confirmed by 15N isotope dilution in the plant tissue and in a plant product, chlorophyll. All of these observations were in contrast to uninoculated plants, plants inoculated with a nitrogen-fixing mutant of Kp342, and plants inoculated with dead Kp342 cells. Nitrogenase reductase was produced by Kp342 in the intercellular space of the root cortex. Wild-type Kp342 and the nifH mutant colonized the interior of wheat roots in equal numbers on a fresh weight basis. The nitrogen fixation phenotype described here was specific to cv. Trenton. Inoculation of cvs. Russ or Stoa with Kp342 resulted in no relief of nitrogen deficiency symptoms.

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Garvin, S., and W. C. Lindemann. "Isolation, characterization, and inoculation of N2-fixing bacteria from dicotyledonous plants." Canadian Journal of Microbiology 32, no. 12 (December 1, 1986): 912–16. http://dx.doi.org/10.1139/m86-168.

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N2-flxing (acetylene-reducing) bacteria were isolated from roots of five species of wild plants in southern New Mexico. Ground cherry (Physalis wrightii) had the highest frequency of roots with N2-fixing bacteria. Acetylene reduction rates of subcultures were comparable with rates exhibited by Azospirillum (300–500 nmol ethylene∙h−1). Three isolates from ground cherry were characterized to the generic level and one to the level of genus and species. Three of these isolates were identified as Enterobacter spp, while the fourth isolate was identified as Azospirillum brasilense. Inoculation of ground cherry with N2-fixing isolates had minimal effects on plant growth, plant nitrogen content, or plant acetylene reduction activity 7 weeks after inoculation. Comparisons between uninoculated and inoculated plants were generally not statistically significant. Significant acetylene reduction activity and high numbers of N2-fixing bacteria occurred only on the roots of plants grown with little or no added nitrogen.

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Preininger, É., P. Korányi, and I. Gyurján. "IN VITRO METHODS OF CREATING PLANTS CONTAINING NITROGEN FIXING BACTERIA." Acta Horticulturae, no. 447 (October 1997): 603–4. http://dx.doi.org/10.17660/actahortic.1997.447.117.

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Franche, Claudine, Kristina Lindström, and Claudine Elmerich. "Nitrogen-fixing bacteria associated with leguminous and non-leguminous plants." Plant and Soil 321, no. 1-2 (December 3, 2008): 35–59. http://dx.doi.org/10.1007/s11104-008-9833-8.

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Westhoek, Annet, Laura J. Clark, Michael Culbert, Neil Dalchau, Megan Griffiths, Beatriz Jorrin, Ramakrishnan Karunakaran, et al. "Conditional sanctioning in a legume–Rhizobium mutualism." Proceedings of the National Academy of Sciences 118, no. 19 (May 3, 2021): e2025760118. http://dx.doi.org/10.1073/pnas.2025760118.

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Legumes are high in protein and form a valuable part of human diets due to their interaction with symbiotic nitrogen-fixing bacteria known as rhizobia. Plants house rhizobia in specialized root nodules and provide the rhizobia with carbon in return for nitrogen. However, plants usually house multiple rhizobial strains that vary in their fixation ability, so the plant faces an investment dilemma. Plants are known to sanction strains that do not fix nitrogen, but nonfixers are rare in field settings, while intermediate fixers are common. Here, we modeled how plants should respond to an intermediate fixer that was otherwise isogenic and tested model predictions using pea plants. Intermediate fixers were only tolerated when a better strain was not available. In agreement with model predictions, nodules containing the intermediate-fixing strain were large and healthy when the only alternative was a nonfixer, but nodules of the intermediate-fixing strain were small and white when the plant was coinoculated with a more effective strain. The reduction in nodule size was preceded by a lower carbon supply to the nodule even before differences in nodule size could be observed. Sanctioned nodules had reduced rates of nitrogen fixation, and in later developmental stages, sanctioned nodules contained fewer viable bacteria than nonsanctioned nodules. This indicates that legumes can make conditional decisions, most likely by comparing a local nodule-dependent cue of nitrogen output with a global cue, giving them remarkable control over their symbiotic partners.

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Taylor, Benton N., and Laura R. Ostrowsky. "Nitrogen-fixing and non-fixing trees differ in leaf chemistry and defence but not herbivory in a lowland Costa Rican rain forest." Journal of Tropical Ecology 35, no. 6 (August 27, 2019): 270–79. http://dx.doi.org/10.1017/s0266467419000233.

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AbstractNitrogen-fixing plants provide critical nitrogen inputs that support the high productivity of tropical forests, but our understanding of the ecology of nitrogen fixers – and especially their interactions with herbivores – remains incomplete. Herbivores may interact differently with nitrogen fixers vs. non-fixers due to differences in leaf nitrogen content and herbivore defence strategies. To examine these potential differences, our study compared leaf carbon, nitrogen, toughness, chemical defence and herbivory for four nitrogen-fixing tree species (Inga oerstediana, Inga sapindoides, Inga thibaudiana and Pentaclethra macroloba) and three non-fixing species (Anaxagorea crassipetala, Casearia arborea and Dipteryx panamensis) in a lowland tropical rain forest. Leaf chemical defence, not nutritional content, was the primary driver of herbivore damage among our species. Even though nitrogen fixers exhibited 21.1% higher leaf nitrogen content, 20.1% lower C:N ratios and 15.4% lower leaf toughness than non-fixers, we found no differences in herbivory or chemical defence between these two plant groups. Our results do not support the common hypotheses that nitrogen fixers experience preferential herbivory or that they produce more nitrogen-rich defensive compounds than non-fixers. Rather, these findings suggest strong species-specific differences in plant–herbivore relationships among both nitrogen-fixing and non-fixing tropical trees.

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Yasuda, Michiko, Khondoker M. G. Dastogeer, Elsie Sarkodee-Addo, Chihiro Tokiwa, Tsuyoshi Isawa, Satoshi Shinozaki, and Shin Okazaki. "Impact of Azospirillum sp. B510 on the Rhizosphere Microbiome of Rice under Field Conditions." Agronomy 12, no. 6 (June 5, 2022): 1367. http://dx.doi.org/10.3390/agronomy12061367.

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There has been increasing attention toward the influence of biofertilizers on the composition of microbial communities associated with crop plants. We investigated the impact of Azospirillum sp. B510, a bacterial strain with nitrogen-fixing ability, on the structure of bacterial and fungal communities within rice plant rhizospheres by amplicon sequencing at two sampling stages (the vegetative and harvest stages of rice). Principal coordinate analysis (PCoA) demonstrated a significant community shift in the bacterial microbiome when the plants were inoculated with B510 at the vegetative stage, which was very similar to the effect of chemical N-fertilizer application. This result suggested that the inoculation with B510 strongly influenced nitrogen uptake by the host plants under low nitrogen conditions. Least discriminant analysis (LDA) showed that the B510 inoculation significantly increased the N2-fixing Clostridium, Aeromonas and Bacillus populations. In contrast, there was no apparent influence of B510 on the fungal community structure. The putative functional properties of bacteria were identified through PICRUSt2, and this hinted that amino acid, sugar and vitamin production might be related to B510 inoculation. Our results indicate that B510 inoculation influenced the bacterial community structure by recruiting other N2-fixing bacteria in the absence of nitrogen fertilizer.

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Khudaygulov, G. G., and S. P. Chetverikov. "Bacteria mitigating herbicidal stress in plants." Biomics 12, no. 3 (2020): 337–42. http://dx.doi.org/10.31301/2221-6197.bmcs.2020-21.

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Bacteria resistant to herbicide solutions were isolated and identified as Pseudomonas. The strains are capable of synthesizing auxins, fixing atmospheric nitrogen and solubilizing phosphates, and can be recommended for creating biological plant protection products with the properties of biofungicide and biofertilizer, and use as bacterial antistressants to mitigate herbicide stress.

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Wu, Lin, and Armando Torres. "EFFECTS OF TALL FESCUE TURF ON GROWTH AND NITROGEN FIXATION POTENTIAL OF THE WOODY LEGUME LUPINUS ALBIFRONS." HortScience 25, no. 9 (September 1990): 1104c—1104. http://dx.doi.org/10.21273/hortsci.25.9.1104c.

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The effect of tall fescue turf on growth, flowering, modulation, and nitrogen fixing potential of Lupinus albifrons Benth. was examined for greenhouse and field grown plants. No allelopathic effect was observed for lupine plants treated with tall fescue leachates. The nitrogen-fixing potential measured by nodule dry weight and acetylene reduction rates was not significantly affected by either tall fescue turf or low nitrogen fertilization. Both the greenhouse and field studies showed that the growth, sexual reproductive allocation, and number of inflorescences were significantly reduced when lupine plants were grown with tall fescue. The root length densities of tall fescue turf and lupine monoculture were measured. The tall fescue turf had 20 times higher root length density (20 cm cm-3 soil) than the lupine plants monoculture. This suggests that intense competition at the root zone may be a dominant factor which limits the growth of the lupine plants. The reproductive characters of the lupine plants was improved by phosphorus fertilization. Transplanting of older lupine plants into the turf substantially alleviated the tall fescue turf competitive effect.

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Tognetti, Pedro M., Suzanne M. Prober, Selene Báez, Enrique J. Chaneton, Jennifer Firn, Anita C. Risch, Martin Schuetz, et al. "Negative effects of nitrogen override positive effects of phosphorus on grassland legumes worldwide." Proceedings of the National Academy of Sciences 118, no. 28 (July 6, 2021): e2023718118. http://dx.doi.org/10.1073/pnas.2023718118.

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Anthropogenic nutrient enrichment is driving global biodiversity decline and modifying ecosystem functions. Theory suggests that plant functional types that fix atmospheric nitrogen have a competitive advantage in nitrogen-poor soils, but lose this advantage with increasing nitrogen supply. By contrast, the addition of phosphorus, potassium, and other nutrients may benefit such species in low-nutrient environments by enhancing their nitrogen-fixing capacity. We present a global-scale experiment confirming these predictions for nitrogen-fixing legumes (Fabaceae) across 45 grasslands on six continents. Nitrogen addition reduced legume cover, richness, and biomass, particularly in nitrogen-poor soils, while cover of non–nitrogen-fixing plants increased. The addition of phosphorous, potassium, and other nutrients enhanced legume abundance, but did not mitigate the negative effects of nitrogen addition. Increasing nitrogen supply thus has the potential to decrease the diversity and abundance of grassland legumes worldwide regardless of the availability of other nutrients, with consequences for biodiversity, food webs, ecosystem resilience, and genetic improvement of protein-rich agricultural plant species.

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46

Markham, John H. "Variability of nitrogen-fixing Frankia on Alnus species." Botany 86, no. 5 (May 2008): 501–10. http://dx.doi.org/10.1139/b08-023.

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Plants maintain mutualistic symbioses with multiple symbiont genotypes that differ in the benefits they provide. To investigate differences in the effect of nitrogen-fixing Frankia on Alnus species, spore-producing (sp+) nodules from Alnus rubra Bong. and Alnus incana subsp. rugosa (Du Roi) Clausen and non-spore-producing (sp–) nodules from Alnus viridis subsp. crispa (Ait.) Turrill, A. rubra, and A. incana subsp. rugosa were collected from each of four different populations and used to inoculate all three Alnus species. As expected, sp+ Frankia produced significantly more nodules on all three species. However, A. crispa, which normally does not have sp+ nodules in the field, was more susceptible to a high level of infection by sp+ Frankia in general, and by any source of sp+ Frankia in particular, whereas A. incana subsp. rugosa, which has the highest abundance of sp+ in the field, was less susceptible to high levels of infection. This suggests that A. incana subsp. rugosa develops resistance to high levels of infection. The infectivity of an sp+ Frankia source on A. viridis subsp. crispa and A. rubra was positively correlated with the proportion of sp+ nodules on the site it was collected from, suggesting that the variation in the abundance of sp+ in the field is caused by sp+ Frankia with different levels of infectivity. There was no effect of Frankia sources on nodule allocation. Plant growth was positively correlated with the specific nodule mass and the specific nodule activity, and negatively correlated with the nodule number per plant. Sp+ Frankia resulted in significantly smaller plants in A. rubra. While there was no overall sp+ type effect on the growth of A. viridis subsp. crispa, the largest plants always resulted when they were inoculated with sp–, and the smallest with sp+ Frankia. Neither spore type nor inoculum source had any effect on the performance of A. rugosa. These results suggest that Alnus species remain susceptible to infection by both Frankia spore types, but are able to modulate the effectiveness of these spore types when they are the common symbionts in the field.

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Hurek, Thomas, Linda L. Handley, Barbara Reinhold-Hurek, and Yves Piché. "Azoarcus Grass Endophytes Contribute Fixed Nitrogen to the Plant in an Unculturable State." Molecular Plant-Microbe Interactions® 15, no. 3 (March 2002): 233–42. http://dx.doi.org/10.1094/mpmi.2002.15.3.233.

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The extent to which the N2-fixing bacterial endophyte Azoarcus sp. strain BH72 in the rhizosphere of Kallar grass can provide fixed nitrogen to the plant was assessed by evaluating inoculated plants grown in the greenhouse and uninoculated plants taken from the natural environment. The inoculum consisted of either wild-type bacteria or nifK¯ mutant strain BHNKD4. In N2-deficient conditions, plants inoculated with strain BH72 (N2-fixing test plants) grew better and accumulated more nitrogen with a lower δ15N signature after 8 months than did plants inoculated with the mutant strain (non-N2-fixing control plants). Polyadenylated or polymerase chain reaction-amplified BH72 nifH transcripts were retrieved from test but not from control plants. BH72 nifH transcripts were abundant. The inocula could not be reisolated. These results indicate that Azoarcus sp. BH72 can contribute combined N2 to the plant in an unculturable state. Abundant BH72 nifH transcripts were detected also in uninoculated plants taken from the natural environment, from which Azoarcus sp. BH72 also could not be isolated. Quantification of nitrogenase gene transcription indicated a high potential of strain BH72 for biological N2 fixation in association with roots. Phylogenetic analysis of nitrogenase sequences predicted that uncultured grass endophytes including Azoarcus spp. are ecologically dominant and play an important role in N2-fixation in natural grass ecosystems.

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Pandharikar, Gaurav, Jean-Luc Gatti, Jean-Christophe Simon, Pierre Frendo, and Marylène Poirié. "Aphid infestation differently affects the defences of nitrate-fed and nitrogen-fixing Medicago truncatula and alters symbiotic nitrogen fixation." Proceedings of the Royal Society B: Biological Sciences 287, no. 1934 (September 2, 2020): 20201493. http://dx.doi.org/10.1098/rspb.2020.1493.

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Legumes can meet their nitrogen requirements through root nodule symbiosis, which could also trigger plant systemic resistance against pests. The pea aphid Acyrthosiphon pisum , a legume pest, can harbour different facultative symbionts (FS) influencing various traits of their hosts. It is therefore worth determining if and how the symbionts of the plant and the aphid modulate their interaction. We used different pea aphid lines without FS or with a single one ( Hamiltonella defensa , Regiella insecticola, Serratia symbiotica ) to infest Medicago truncatula plants inoculated with Sinorhizobium meliloti (symbiotic nitrogen fixation, SNF) or supplemented with nitrate (non-inoculated, NI). The growth of SNF and NI plants was reduced by aphid infestation, while aphid weight (but not survival) was lowered on SNF compared to NI plants. Aphids strongly affected the plant nitrogen fixation depending on their symbiotic status, suggesting indirect relationships between aphid- and plant-associated microbes. Finally, all aphid lines triggered expression of Pathogenesis-Related Protein 1 ( PR1 ) and Proteinase Inhibitor (PI) , respective markers for salicylic and jasmonic pathways, in SNF plants, compared to only PR1 in NI plants. We demonstrate that the plant symbiotic status influences plant–aphid interactions while that of the aphid can modulate the amplitude of the plant's defence response.

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Sumaira Mazhar, Sumaira Mazhar, and Jerry D. Cohen and Shahida Hasnain Jerry D Cohen and Shahida Hasnain. "Novel Approach for the Determination of Nitrogen Fixation in Cyanobacteria." Journal of the chemical society of pakistan 41, no. 1 (2019): 105. http://dx.doi.org/10.52568/000711/jcsp/41.01.2019.

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Non-heterocystous nitrogen fixing strains of cyanobacteria were screened by their ability to grow in nitrogen deficient media. The selected nitrogen fixing cyanobacterial cells were then cultured in BG11 media supplemented with [15N]-labeled sodium nitrate. Under these growth conditions any organic [14N] found in the cyanobacterial cells would simply come from nitrogen fixation because [15N] was the only available source of nitrogen in the medium. Amino acids extracted after different time periods (after 15, 30, 40, 50 and 60 days of inoculation) were used for the determination of the 14N/15N ratio using GC-MS. Results from the present study support the conclusion that at stationary phase of growth cyanobacterial nitrogen fixation was no longer supplying a significant amount of nitrogen. This approach not only provided a detailed method for the evaluation of the nitrogen fixing potential of the cyanobacteria in culture, but also suggests novel approaches for the assessment of the ability of the strains to provide nitrogen enrichment to plants under co-cultivation conditions.

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Machray, G. C., and W. D. P. Stewart. "Genetics of plant-microbe nitrogen-fixing symbiosis." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 85, no. 3-4 (1985): 239–52. http://dx.doi.org/10.1017/s0269727000004048.

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SynopsisA wide variety of plant-microbe nitrogen-fixing symbioses which include cyanobacteria as the nitrogenfixing partner exist. While some information has been gathered on the biochemical changes in the cyanobacterium upon entering into symbiosis, very little is known about the accompanying changes at the genetic level. Much of our present knowledge of the organisation and control of expression of nitrogenfixation (nif) genes is derived from studies of the free-living diazotroph Klebsiella pneumoniae. This organism thus provides a model system and source of experimental material for the genetic analysis of symbiotic nitrogen fixation. We describe the use of cloned K. pneumoniae genes for nitrogen fixation and its regulation in the genetic analysis' of nitrogen fixation in cyanobacteria which can enter into symbiosis with plants. These studies reveal some dissimilarities in the organisation of nif genes and raise questions as to the genetic control of nitrogen fixation in symbiosis.

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Journal articles on the topic 'Nitrogen-fixing plants'

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