Chemical Structure of the Core Region of Lipopolysaccharides
Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison in Endotoxin in Health and Disease, 2020
Bacteria of the genera Rhizobium and Bradyrhizobium live in symbiosis with legume plants and participate in the process of nitrogen assimilation. Several partial core structures of LPS from R. leguminisarum, R. meliloti, and B. japonicum have been published (Table 9) (219, 226). The core structure of R. etli CE3 comprises two oligosaccharides, which have also been isolated from R. leguminisarum bv. trifolii strains ANU843 and 24.1, a branched tetrasaccharide consisting of Gal, Man, GalA, and Kdo, which is substituted at 0–4 of Kdo by a branched trisaccharide built up from two GalA and one Kdo residues (226,227). In both species, the O-antigen is linked to O-6 of the Gal residue of the tetrasaccharide unit, and in the core of R. etli this is furnished via a third Kdo residue. The anomeric configuration of the Kdo residues are not published.
The Rhizobium/Bradyrhizobium-Legume Symbiosis
Peter M. Gresshoff in Molecular Biology of Symbiotic Nitrogen Fixation, 2018
Rhizobium and Brady rhizobium bacteria are unique among microorganisms in their ability to induce the formation of nitrogen-fixing nodules on leguminous plants. Nodule formation involves a specific recognition between the prokaryotic and eukaryotic partners, invasion of plant cells by bacteria, and many changes in the structure and biochemistry of both organisms as the nodule develops. Not surprisingly, this process is associated with changes in the expression of many genes in both the bacteria and the host plant. Genetic analysis of the bacterial partner has led to the identification of about three dozen "symbiotic genes", that is, genes whose functions are required for the development of a nitrogen-fixing nodule, but not for vegetative growth of the bacteria. This review will consider a number of recent advances in the identification and characterization of symbiotic genes, with particular emphasis on genes controlling early stages of infection and nodule development. It should be kept in mind that many other bacterial genes, not discussed here, may be involved in symbiosis and may also function in other cellular processes. For example, auxotrophic mutants frequently form nodules that do not fix nitrogen or fail to form nodules at all. Still other genes are involved in ancillary functions such as hydrogen recycling, but are not required for symbiosis per se. Several recent papers review various aspects of the genetic control of nodule formation and function.1-14
Legumes
Christopher Cumo in Ancestral Diets and Nutrition, 2020
Egyptians and Romans observed that legumes improved soil fertility without understanding why. In 1886, German chemists Hermann Hellriegel (1831–1895) and Hermann Wilfarth (1853–1904) supplied the answer by describing nitrogen fixation.7Rhizobium bacteria and legumes interact symbiotically. The bacteria infect legume root filaments, known as hairs, forming nodules. Nodules shelter these bacteria, which convert the soil’s nitrogen gas (N2) into ammonium cations (NH4+). Plants, and in turn herbivores and omnivores, depend on this transformation because roots cannot absorb nitrogen gas but can take up ions as nourishment. Ammonium benefits not only legumes. Unabsorbed surplus remains available for next year’s crops.
Graphene oxide influence in soil bacteria is dose dependent and changes at osmotic stress: growth variation, oxidative damage, antioxidant response, and plant growth promotion traits of a Rhizobium strain
Published in Nanotoxicology, 2022
Tiago Lopes, Paulo Cardoso, Diana Matos, Ricardo Rocha, Adília Pires, Paula Marques, Etelvina Figueira
Rhizobium sp. strain E20-8 was previously isolated from the root nodules of Pisum sativum L. (Figueira and de 2000). The 16S rRNA gene was amplified, the PCR products were sequenced and used to identify the bacterium strain to genus level as described by Cardoso et al. (2018). The partial 16S rRNA gene sequence was deposited in GenBank (Accession: KY491644). Rhizobium sp. strain E20-8 was previously described as osmotolerant (Cardoso, Freitas, and Figueira 2015) and as promoting plant growth (Figueira and de 2000). The strain was grown overnight at 26 °C in an orbital shaker (160 rpm) in tubes containing 5 ml of Yeast Mannitol Broth (YMB) medium (Somasegaran and Hoben 1994). Bacteria number was performed by attempting several dilutions and the usage of the Neubauer chamber, allowing the formulation of a linear regression relating optical density and the amount of bacterial cells (M cells) (
Insights in nodule-inhabiting plant growth promoting bacteria and their ability to stimulate Vicia faba growth
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Amr M. Mowafy, Mona S. Agha, Samia A. Haroun, Mohamed A. Abbas, Mohamed Elbalkini
Symbiotic nitrogen fixation, which is positioned as a major part of biological nitrogen fixation, is an important alternative source of chemical nitrogen fertilizers not only for leguminous but also for non-leguminous plants. The interaction between legumes and rhizobia leads to root nodule organogenesis, an organ that is produced in response to bacterial nod factors and plant developmental signals leading to the formation of a plant stem cell niche [1]. Recently, rhizobia have been shown to improve the nutrition of non-leguminous crops, such as barley, wheat and canola [2]. It has been established that the legume nodule is exclusively inhabited by the rhizobium. Meanwhile, in 2001, this concept has changed dramatically when non-rhizobial strains were regarded for their ability to nodulate legumes, such as Methylobacterium and Burkholderia that have been isolated from Crotalaria [3] and Mimosa [4], respectively. In addition to nodule-inducing bacteria, several bacterial strains have been isolated from nodules as co-inhabitants with rhizobium, such as Klebsiella, Pseudomonas [5], Bacillus [6] and Streptomyces [7]. Interestingly, a review titled ‘the nodule microbiome: N2-fixing rhizobia do not live alone’ has been published in 2017 to conclude that some of these non-rhizobial bacteria might be nitrogen fixer or participate in nodule genesis and the others, more striking, might neither participate in nodulation nor fix nitrogen [8].
Echinacea biotechnology: advances, commercialization and future considerations
Published in Pharmaceutical Biology, 2018
Jessica L. Parsons, Stewart I. Cameron, Cory S. Harris, Myron L. Smith
Hairy root culture utilizes the natural ability of the soil bacterium Rhizobium rhizogenes (formerly Agrobacterium rhizogenes) to infect and transform plant tissue. The bacterial Ri plasmid is transferred into the plant genome causing neoplastic outgrowths, but incorporation of a set of genes, rolA, rolB and rolC, causes roots to grow from the infected site instead of an undifferentiated cell mass (Nilsson and Olsson 1997; Pistelli et al. 2010). Hairy root cultures have several properties that are useful for research and industry, including accelerated growth, spontaneous regeneration of shoots, as well as chemical and morphological similarity to the roots of a wild-type plant (Tepfer 1990; Guillon et al. 2006). Hairy root cultures of all three commercially important Echinacea species produce high levels of secondary metabolites, including polysaccharides, alkylamides, CADs and other phenolics (Trypsteen et al. 1991; Liu et al. 2006; Wang et al. 2006; Romero et al. 2009; Pistelli et al. 2010). Transformed roots are genetically stable, and maintain a constant production of metabolites over a long period of time (Wu et al. 2006). The rapid growth of hairy root cultures on hormone-free media makes them an excellent way to generate biomass quickly, or to clonally propagate plants.
Related Knowledge Centers
- Ammonia
- Bacteria
- Glutamine
- Nitrogen Fixation
- Nitrogenase
- Root Nodule
- Gram-Negative Bacteria
- Endosymbiont
- Legume
- Acylurea