Nitrogen fixation

About: Nitrogen fixation is a research topic. Over the lifetime, 7940 publications have been published within this topic receiving 232921 citations. The topic is also known as: GO:0009399.

Nitrogen Fixation and Delayed Leaf Senescence in Soybeans

Abstract: Delayed leaf senescence has been found in a soybean population which maintains its chlorophyll and ribulosebisphosphate carboxylase activity in leaves and nitrogen fixation (acetylene reduction) activity in root nodules throughout seed maturation. Incorporation of delayed leaf senescence into an agronomically desirable genetic background may help to increase seed yield and symbiotic nitrogen fixation during seed development.

Molecular characterization and identification of plant growth promoting endophytic bacteria isolated from the root nodules of pea ( Pisum sativum L.)

Abstract: Root nodule accommodates various non-nodulating bacteria at varying densities. Present study was planned to identify and characterize the non-nodulating bacteria from the pea plant. Ten fast growing bacteria were isolated from the root nodules of cultivated pea plants. These bacterial isolates were unable to nodulate pea plants in nodulation assay, which indicate the non-rhizobial nature of these bacteria. Bacterial isolates were tested in vitro for plant growth promoting properties including indole acetic acid (IAA) production, nitrogen fixation, phosphate solubilization, root colonization and biofilm formation. Six isolates were able to produce IAA at varying level from 0.86 to 16.16 μg ml(-1), with the isolate MSP9 being most efficient. Only two isolates, MSP2 and MSP10, were able to fix nitrogen. All isolates were able to solubilize inorganic phosphorus ranging from 5.57 to 11.73 μg ml(-1), except MSP4. Bacterial isolates showed considerably better potential for colonization on pea roots. Isolates MSP9 and MSP10 were most efficient in biofilm formation on polyvinyl chloride, which indicated their potential to withstand various biotic and abiotic stresses, whereas the remaining isolates showed a very poor biofilm formation ability. The most efficient plant growth promoting agents, MSP9 and MSP10, were phylogenetically identified by 16S rRNA gene sequence analysis as Ochrobactrum and Enterobacter, respectively, with 99% similarity. It is suggested the potential endophytic bacterial strains, Ochrobactrum sp. MSP9 and Enterobacter sp. MSP10, can be used as biofertilizers for various legume and non-legume crops after studying their interaction with the host crop and field evaluation.

Molybdenum in nitrogenase

Abstract: Publisher Summary Nitrogen fixation ranks with photosynthesis as a process of fundamental importance to all life on earth. The biochemical process described by nitrogen fixation is the reduction of N2 to NH3, which can then be used for the synthesis of amino acids, nucleic acids, and other essential nitrogenous compounds. Intensive agricultural methods have led to increased use of and dependence on manufactured nitrogenous fertilizers with decreased emphasis on biological nitrogen fixation. However, with the depletion of fossil fuels, the cost of fertilizer production is rising, and this situation could easily lead to a worldwide food crisis. One aspect of nitrogen fixation that is receiving an increased amount of interest is the role of the element molybdenum. The enzyme nitrogenase that catalyzes the reduction of N2 to NH3 is one of a handful of enzymes that relies absolutely on Mo for catalytic activity. This fact has practical significance for agriculture since certain soils that could just barely support the growth of nitrogen-fixing legumes and could be greatly improved simply by addition of trace levels of Mo.

A metabolic signature of the beneficial interaction of the endophyte paenibacillus sp. isolate and in vitro-grown poplar plants revealed by metabolomics.

Abstract: Metabolic profiling via gas chromatography coupled to mass spectrometry was used to investigate the influence of endophytic bacteria on shoots of in vitro-grown poplar plants free from culturable endophytic bacteria. The results demonstrate that the occurrence of an endophytic Paenibacillus strain strongly affects the composition of the plant metabolites of in vitro-grown poplars. Eleven metabolites were significantly changed between inoculated and non-inoculated poplar plants as determined by two independent experiments. Detected shifts in the primary metabolism of the poplar plants pointed to a mutualistic interaction between bacteria able to fix nitrogen and the host plant with altered nitrogen assimilation patterns. The corresponding metabolic signature comprises increased asparagine and urea levels as well as depleted sugars and organic acids of the tricarboxylic acid cycle. These observations coincide with the fact that the Paenibacillus sp. strain P22 is able to grow without nitrogen in the medium, indicating nitrogen fixation from the air also known from other Paenibacillus spp. In combination with the detected plant-growth-promoting effects of the endophyte Paenibacillus P22, a novel mutualistic interaction is observed.