Nodulation is the temporally and quantitatively predominant cellular defense response to bacterial infection in insects and other invertebrates. Inhibition of eicosanoid biosynthesis in larvae of the tenebrionid beetle, Zophobas atratus, immediately prior to intrahemocoelic injections with heat killed preparations of the bacterium, Serratia marcescens, strongly reduced the nodulation response. ...

Nodulation is tightly regulated in legumes to ensure appropriate levels of nitrogen fixation without excessive depletion of carbon reserves. This balance is maintained by intimately linking nodulation and its regulation with plant hormones. It has previously been shown that ethylene and jasmonic acid (JA) are able to regulate nodulation and Nod factor signal transduction. Here, we characterize ...

The CLAVATA3/embryo-surrounding region (CLE) peptides control the fine balance between proliferation and differentiation in plant development. We studied the role of CLE peptides during indeterminate nodule development and identified 25 MtCLE peptide genes in the Medicago truncatula genome, of which two genes, MtCLE12 and MtCLE13, had nodulation-related expression patterns that were linked to p...

Nodulation is the temporally and quantitatively most important cellular defense response to bacterial, fungal and some viral infections in insects. We tested the hypothesis that prostaglandins and other eicosanoids are responsible for mediating nodulation reactions to bacterial infection in larvae of the blowfly Chrysomya megacephala. Third-instar larvae treated with Ureaplasma urealyticum form...

Strains in Bradyrhizobium japonicum serocluster 123 are the major indigenous competitors for nodulation in a large portion of the soybean production area of the United States. Serocluster 123 is defined by the serotype strains USDA 123, USDA 127, and USDA 129. The objective of the work reported here was to evaluate the ability of two soybean genotypes, PI 377578 and PI 417566, to restrict the n...

During the course of evolution, mainly leguminous plants have acquired the ability to form de novo structures called root nodules. Recent studies on the autoregulation and hormonal controls of nodulation have identified key mechanisms and also indicated a possible link to other developmental processes, such as the formation of the shoot apical meristem (SAM). However, our understanding of nodul...

Production of grain legumes is severely reduced in salt-affected soils because their ability to form and maintain nitrogen-fixing nodules is impaired by both salinity and sodicity (alkalinity). Genotypes of chickpea, Cicer arietinum, with high nodulation capacity under stress were identified by field screening in a sodic soil in India and subsequently evaluated quantitatively for nitrogen fixat...

Cowpea (Vigna unguiculata) and peanut (Arachis hypogaea) in southern Africa are nodulated by a genetically diverse group of Bradyrhizobium strains. To determine the identity of these bacteria, a collection of 22 isolates originating from the root nodules of both hosts in Botswana and South Africa was investigated using the combined sequences for the core genome genes rrs, recA, and glnII. These...

Establishing forage legumes into endophyte-infected tall fescue (Festuca arundinacae Schreb.) pastures is problematic, especially in well-established stands. A oversowing field experiment determined if this problem was because of poor nodulation. Four renovation techniques, clipped sward (treatment A), herbicided + rye seeding in the previous autumn (treatment B), herbicided in the autumn and s...

Nodule formation in Rhizobium-legume symbiosis is negatively regulated by ethylene. Ethylene inhibitors such as L-α-(2-amino-ethoxyvinyl)-glycine (AVG) and silver ions (Ag), the ethylene-insensitive sickle mutant, and transgenic plants were used to study ethylene-mediated responses in nodulation. The mode of action of ethylene inhibitors AVG and Ag, and the skl mutation occur at different steps...