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Nodulation and nitrogen fixation

Joy B Winbourne, Matt T Harrison, Ben W Sullivan, Silvia Alvarez-Clare, Silvia R Lins, Luiz Martinelli, Megan Nasto, Daniel Piotto, Samir Rolim, Michelle Wong, Stephen Porder
Symbiotic nitrogen fixation (SNF) makes atmospheric nitrogen biologically available and regulates carbon storage in many terrestrial ecosystems. Despite its global importance, estimates of SNF rates are highly uncertain, particularly in tropical forests where rates are assumed to be high. Here we provide a framework for evaluating the uncertainty of sample-based SNF estimates and discuss its implications for quantifying SNF and thus understanding of forest function. We apply this framework to field data sets from six lowland tropical rainforests (mature and secondary) in Brazil and Costa Rica...
November 2018: American Naturalist
William P Buhian, Sandra Bensmihen
The rhizobia-legume symbiosis is a mutualistic association in which bacteria provide plants with nitrogen compounds and the plant provides bacteria with carbon sources. A successful symbiotic interaction relies on a molecular dialog between the plant and the bacteria, and generally involves rhizobial lipo-chitooligosaccharide signals called Nod factors (NFs). In most cases, specific NF perception is required for rhizobia to enter root cells through newly formed intracellular structures called infection threads (ITs)...
2018: Frontiers in Plant Science
Liyu Chen, Lu Qin, Lili Zhou, Xinxin Li, Zhichang Chen, Lili Sun, Wenfei Wang, Zhihao Lin, Jing Zhao, Naoki Yamaji, Jian Feng Ma, Mian Gu, Guohua Xu, Hong Liao
Symbiotic nitrogen (N2 ) fixation plays a vital role in sustainable agriculture. Efficient N2 fixation requires various materials including phosphate (Pi), however, the molecular mechanism underlying the transport of Pi into nodules and bacteroids remains largely unknown. A nodule-localized Pi transporter, GmPT7 was functionally characterized in soybean (Glycine max) and its role in N2 fixation and yield was investigated via composite and whole transgenic plants. GmPT7 protein was localized to the plasma membrane and showed transport activity for Pi in yeast...
October 14, 2018: New Phytologist
Claus Lang, Melanie J Barnett, Robert F Fisher, Lucinda S Smith, Michelle E Diodati, Sharon R Long
Bacteria must sense alterations in their environment and respond with changes in function and/or structure in order to cope. Extracytoplasmic function sigma factors (ECF σs) modulate transcription in response to cellular and environmental signals. The symbiotic nitrogen-fixing alphaproteobacterium Sinorhizobium meliloti carries genes for 11 ECF-like σs (RpoE1 to -E10 and FecI). We hypothesized that some of these play a role in mediating the interaction between the bacterium and its plant symbiotic partner...
October 10, 2018: MSphere
Guy Dovrat, Efrat Sheffer
1.Plants, especially perennials, growing in drylands and seasonally dry ecosystems are uniquely adapted to dry conditions. Legume shrubs and trees, capable of symbiotic dinitrogen (N2 ) fixation, often dominate in drylands. However, the strategies that allow symbiotic fixation in these ecosystems, and their influence on the nitrogen cycle, are largely unresolved. We evaluated the climatic, biogeochemical and ontogenetic factors influencing nitrogen fixation in an abundant Mediterranean legume shrub, Calicotome villosa...
October 9, 2018: New Phytologist
Jie-Shun Lin, Xiaolin Li, Zhenpeng Luo Luo, Kirankumar S Mysore, Jiangqi Wen, Fang Xie
Legume plants can assimilate inorganic nitrogen and have access to fixed nitrogen through symbiotic interaction with diazotrophic bacteria called rhizobia. Symbiotic nitrogen fixation is an energy-consuming process and is strongly inhibited when sufficient levels of fixed nitrogen are available, but the molecular mechanisms governing this regulation are largely unknown. The transcription factor nodule inception (NIN) is strictly required for nodulation and belongs to a family of NIN-like proteins (NLPs), which have been implicated in the regulation of nitrogen homeostasis in Arabidopsis...
October 8, 2018: Nature Plants
Mustapha Mohammed, Sanjay K Jaiswal, Elias N K Sowley, Benjamin D K Ahiabor, Felix D Dakora
Kersting's groundnut ( Macrotyloma geocarpum Harms) is a neglected, endangered food and medicinal legume in Africa. Efforts to harness the benefits of the legume-rhizobia symbiosis have focused on few major legumes to the neglect of underutilized ones such as Kersting's groundnut. This study assessed plant growth, N-fixed and grain yield of five Kersting's groundnut landraces in response to inoculation with Bradyrhizobium strain CB756 at two locations in the Northern Region of Ghana. The transferability of cowpea-derived Simple Sequence Repeat (SSR) markers to Kersting's groundnut was also assessed...
2018: Frontiers in Microbiology
Amalia Soenens, Margarita Gomila, Juan Imperial
We describe for the first time a non-symbiotic species of the recently described genus Neorhizobium, lacking nodulation or nitrogen fixation genes. The strains were isolated from a dryland agricultural soil in southern Spain where no record of legume cultivation is available, thus we propose the name Neorhizobium tomejilense sp. nov. (type strain T17_20T , LMG 30623T and CECT 9621T ). N. tomejilense exhibit a clear distinct lineage from the other Neorhizobium species, Neorhizobium galegae, Neorhizobium alkalisoli and Neorhizobium huautlense, based on polyphasic evidence...
September 17, 2018: Systematic and Applied Microbiology
Xinxin Li, Jiakun Zheng, Yongqing Yang, Hong Liao
Nodulation is crucial for biological nitrogen fixation (BNF) in legumes, but the molecular mechanisms underlying BNF have remained elusive. Here, we cloned a candidate gene underlying a major nodulation QTL in soybean (Glycine max), INCREASING NODULE SIZE1 (GmINS1). GmINS1 encodes a cell wall a β-expansin, and is primarily expressed in vascular bundles, along with cortical and parenchyma cells of nodules. Four SNPs distinguishing the two parents were found in the GmINS1 promoter region. Among them, SNP A/C has a significant effect on GmINS1 expression in the parental genotype P2, based on GUS activity and promoter deletion analysis...
September 28, 2018: Plant Physiology
María J Lorite, María J Estrella, Francisco J Escaray, Analía Sannazzaro, Isabel M Videira E Castro, Jorge Monza, Juan Sanjuán, Milagros León-Barrios
The symbiosis between Lotus and rhizobia has been long considered very specific and only two bacterial species were recognized as the microsymbionts of Lotus : Mesorhizobium loti was considered the typical rhizobia for the L. corniculatus complex, whereas Bradyrhizobium sp. ( Lotus ) was the symbiont for L. uliginosus and related species. As discussed in this review, this situation has dramatically changed during the last 15 years, with the characterization of nodule bacteria from worldwide geographical locations and from previously unexplored Lotus spp...
2018: Frontiers in Microbiology
G Schwob, M Roy, C A Pozzi, A Herrera-Belaroussi, M P Fernandez
Alnus genus forms symbiosis with the actinobacteria Frankia and ectomycorrhizal fungi. Two types of Frankia lineages can be distinguished based on their ability to sporulate in planta. Spore-positive (Sp+) strains are predominant on Alnus incana ( Ai ) and Alnus viridis ( Av ) in highlands, while spore-negative (Sp-) strains are mainly associated with Alnus glutinosa ( Ag ) in lowlands. Here, we investigated whether the Sp+ predominance in nodules is due to host selection of certain Frankia genotypes from soil communities or the result of the ecological history of the alder stand soil, and the effect of the sporulation genotype on the ECM communities...
September 14, 2018: Applied and Environmental Microbiology
Margarida Saramago, Marta Robledo, Rute G Matos, José I Jiménez-Zurdo, Cecília M Arraiano
Members of the ribonuclease (RNase) III family of enzymes are metal-dependent double-strand specific endoribonucleases. They are ubiquitously found and eukaryotic RNase III-like enzymes include Dicer and Drosha, involved in RNA processing and RNA interference. In this work, we have addressed the primary characterization of RNase III from the symbiotic nitrogen-fixing α-proteobacterium Sinorhizobium meliloti . The S. meliloti rnc gene does encode an RNase III-like protein ( Sm RNase III), with recognizable catalytic and double-stranded RNA (dsRNA)-binding domains that clusters in a branch with its α-proteobacterial counterparts...
2018: Frontiers in Genetics
Xia Kang, Xiumei Yu, Yu Zhang, Yongliang Cui, Weiguo Tu, Qiongyao Wang, Yanmei Li, Lanfang Hu, Yunfu Gu, Ke Zhao, Quanju Xiang, Qiang Chen, Menggen Ma, Likou Zou, Xiaoping Zhang, Jinsan Kang
Metalliferous mine tailings have a negative impact on the soil environment near mining areas and render cultivable lands infertile. Phytoremediation involving the synergism of legume and rhizobia provides a useful technique in tackling this issue with cost-effective, environmentally friendly, and easy-to-use features under adverse soil conditions. Leucaena leucocephala has been found to build symbiotic relationships with native rhizobia in the iron-vanadium-titanium oxide (V-Ti magnetite) mine tailing soil...
2018: Frontiers in Microbiology
Alejandro Aguilar, Yolanda Mora, Araceli Dávalos, Lourdes Girard, Jaime Mora, Humberto Peralta
BACKGROUND: Rhizobia are alpha-proteobacteria commonly found in soil and root nodules of legumes. It was recently reported that nitrogen-fixing rhizobia also inhabit legume seeds. In this study, we examined whole-genome sequences of seven strains of rhizobia isolated from seeds of common bean (Phaseolus vulgaris). RESULTS: Rhizobial strains included in this study belonged to three different species, including Rhizobium phaseoli, R. leguminosarum, and R. grahamii...
August 30, 2018: BMC Genomics
Mónica Rosenblueth, Ernesto Ormeño-Orrillo, Aline López-López, Marco A Rogel, Blanca Jazmín Reyes-Hernández, Julio C Martínez-Romero, Pallavolu M Reddy, Esperanza Martínez-Romero
Cereals such as maize, rice, wheat and sorghum are the most important crops for human nutrition. Like other plants, cereals associate with diverse bacteria (including nitrogen-fixing bacteria called diazotrophs) and fungi. As large amounts of chemical fertilizers are used in cereals, it has always been desirable to promote biological nitrogen fixation in such crops. The quest for nitrogen fixation in cereals started long ago with the isolation of nitrogen-fixing bacteria from different plants. The sources of diazotrophs in cereals may be seeds, soils, and even irrigation water and diazotrophs have been found on roots or as endophytes...
2018: Frontiers in Microbiology
Thomas Pfau, Nils Christian, Shyam K Masakapalli, Lee J Sweetlove, Mark G Poolman, Oliver Ebenhöh
Genome-scale metabolic network models can be used for various analyses including the prediction of metabolic responses to changes in the environment. Legumes are well known for their rhizobial symbiosis that introduces nitrogen into the global nutrient cycle. Here, we describe a fully compartmentalised, mass and charge-balanced, genome-scale model of the clover Medicago truncatula, which has been adopted as a model organism for legumes. We employed flux balance analysis to demonstrate that the network is capable of producing biomass components in experimentally observed proportions, during day and night...
August 21, 2018: Scientific Reports
Sebastian Pfeilmeier, Jeoffrey George, Arry Morel, Sonali Roy, Matthew Smoker, Lena Stransfeld, J Allan Downie, Nemo Peeters, Jacob G Malone, Cyril Zipfel
Interfamily transfer of plant pattern recognition receptors (PRRs) represents a promising biotechnological approach to engineer broad-spectrum, and potentially durable, disease resistance in crops. It is however unclear whether new recognition specificities to given pathogen-associated molecular patterns (PAMPs) affect the interaction of the recipient plant with beneficial microbes. To test this in a direct reductionist approach, we transferred the Brassicaceae-specific PRR ELONGATION FACTOR-THERMO UNSTABLE RECEPTOR (EFR), conferring recognition of the bacterial EF-Tu protein, from Arabidopsis thaliana to the legume Medicago truncatula...
August 18, 2018: Plant Biotechnology Journal
Matthew G Garneau, Qiumin Tan, Mechthild Tegeder
Legumes fix atmospheric nitrogen through a symbiotic relationship with bacteroids in root nodules. Following fixation in pea (Pisum sativum L.) nodules, nitrogen is reduced to amino acids that are exported via the nodule xylem to the shoot, and in the phloem to roots in support of growth. However, the mechanisms involved in amino acid movement towards the nodule vasculature, and their importance for nodule function and plant nutrition, were unknown. We found that in pea nodules the apoplasmic pathway is an essential route for amino acid partitioning from infected cells to the vascular bundles, and that amino acid permease PsAAP6 is a key player in nitrogen retrieval from the apoplasm into inner cortex cells for nodule export...
October 12, 2018: Journal of Experimental Botany
Paulina Estrada-de Los Santos, Marike Palmer, Belén Chávez-Ramírez, Chrizelle Beukes, Emma T Steenkamp, Leah Briscoe, Noor Khan, Marta Maluk, Marcel Lafos, Ethan Humm, Monique Arrabit, Matthew Crook, Eduardo Gross, Marcelo F Simon, Fábio Bueno Dos Reis Junior, William B Whitman, Nicole Shapiro, Philip S Poole, Ann M Hirsch, Stephanus N Venter, Euan K James
Burkholderia sensu lato is a large and complex group, containing pathogenic, phytopathogenic, symbiotic and non-symbiotic strains from a very wide range of environmental (soil, water, plants, fungi) and clinical (animal, human) habitats. Its taxonomy has been evaluated several times through the analysis of 16S rRNA sequences, concantenated 4⁻7 housekeeping gene sequences, and lately by genome sequences. Currently, the division of this group into Burkholderia , Caballeronia, Paraburkholderia , and Robbsia is strongly supported by genome analysis...
August 1, 2018: Genes
Mostafa Abdelrahman, Magdi A El-Sayed, Abeer Hashem, Elsayed Fathi Abd Allah, Abdulaziz A Alqarawi, David J Burritt, Lam-Son Phan Tran
Phosphate (Pi ) deficiency is a critical environmental constraint that affects the growth and development of several legume crops that are usually cultivated in semi-arid regions and marginal areas. Pi deficiency is known to be a significant limitation for symbiotic nitrogen (N2 ) fixation (SNF), and variability in SNF is strongly interlinked with the concentrations of Pi in the nodules. To deal with Pi deficiency, plants trigger various adaptive responses, including the induction and secretion of acid phosphatases, maintenance of Pi homeostasis in nodules and other organs, and improvement of oxygen (O2 ) consumption per unit of nodule mass...
2018: Frontiers in Plant Science
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