In legumes, the number of symbiotic root nodules is controlled by long-distance communication between the shoot and the root. Mutants defective in this feedback mechanism exhibit a hypernodulating phenotype. Here, we report the identification of a novel leucine-rich repeat receptor-like kinase (LRR-RLK), KLAVIER (KLV), which mediates the systemic negative regulation of nodulation in Lotus japon...

The symbiosis between rhizobial microbes and host plants involves the coordinated expression of multiple genes, which leads to nodule formation and nitrogen fixation. As part of the transcriptional machinery for nodulation and symbiosis across a range of Rhizobium, NolR serves as a global regulatory protein. Here, we present the X-ray crystal structures of NolR in the unliganded form and comple...

Legume plants are capable of entering into a symbiotic relationship with rhizobia bacteria. This results in the formation of novel organs on their roots, called nodules, in which the bacteria capture atmospheric nitrogen and provide it as ammonium to the host plant. Complex molecular and physiological changes are involved in the formation and establishment of such nodules. Several phytohormones...

Introduction Nitrogen fixation by legumes is the product of a symbiosis of legume plants and a group of bacteria known as rhizobia (Carroll, et al., 1985; Kinkema, et al., 2006). It has been hypothesised that when rhizobia receive flavonoid signals from the host plants, production of a chemical nodulation factor is induced. The perception of nodulation factor by legume roots then activates a si...

In this study, we addressed the effects of N limitation in Bradyrhizobium japonicum for its association with soybean roots. The wild-type strain LP 3001 grew for six generations with a growth rate of 1.2 day(-1) in a minimal medium with 28 mM mannitol as the carbon source and with the N source [(NH(4))(2)SO(4)] limited to only 20 microM. Under these conditions, the glutamine synthetase (GS) act...

The response of soybean to biological nitrogen fixation (BNF) varies due factors such as plant variety, soil, and environmental conditions, which can compromise the N2 capacity. objective this study was evaluate additional inoculation with B. japonicum at different growth stages a strategy improve fixation. This determined by studying nodulation BNF isotope dilution method. experiment carried o...

The products of the 'common' nodulation genes of Rhizobium catalyze the synthesis of signal molecules and were once thought to have similar functions in all Rhizobium species; subtle differences in the activities of these gene products have now been discovered that influence the host range of Rhizobium species.

Legume roots form two types of postembryonic organs, lateral roots and symbiotic nodules. Nodule formation is the result of the interaction of legumes with rhizobia and requires the mitotic activation and differentiation of root cells as well as an independent, but coordinated, program that allows infection by rhizobia. MicroRNA390 (miR390) is an evolutionarily conserved microRNA that targets t...

The molecular and physiological mechanisms behind the maturation and maintenance of N(2)-fixing nodules during development of symbiosis between rhizobia and legumes still remain unclear, although the early events of symbiosis are relatively well understood. Azorhizobium caulinodans ORS571 is a microsymbiont of the tropical legume Sesbania rostrata, forming N(2)-fixing nodules not only on the ro...

The rhizobial-derived signaling molecule Nod factor is essential for the establishment of the Medicago truncatula/Sinorhizobium meliloti symbiosis. Nod factor perception and signal transduction in the plant involve calcium spiking and lead to the induction of nodulation gene expression. It has previously been shown that the heterotrimeric G-protein agonist mastoparan can activate nodulation gen...