The early steps of symbiotic nodule formation by Rhizobium on plants require coordinate expression of several nod gene operons, which is accomplished by the activating protein NodD. Three different NodD proteins are encoded by Sym plasmid genes in Rhizobium meliloti, the alfalfa symbiont. NodD1 and NodD2 activate nod operons when Rhizobium is exposed to host plant inducers. The third, NodD3, is...

Cobalt is known to be essential for symbiotic nitrogen fixation by legumes (l-5), but a requirement of the element for growth of leguminous plants supplied with adequate fixed nitrogen has not been shown. Ahmed and Evans (3) provided evidence that cobalt was required for the bacteria within the nodules of inoculated legumes but was not required for the leguminous plants per se. Lowe, Evans, and...

In field peas, ascochyta blight is one of the most common fungal diseases caused by Didymella pinodes. Despite the high diversity of pea cultivars, only little resistance has been developed until to date, still leading to significant losses in grain yield. Rhizobia as plant growth promoting endosymbionts are the main partners for establishment of symbiosis with pea plants. The key role of Rhizo...

Nitrogen (N) fixation through legume-Rhizobium symbiosis is important for enhancing agricultural productivity and is therefore of great economic interest. Growing evidence indicates that other soil beneficial bacteria can positively affect symbiotic performance of rhizobia. Nodule endophytic plant growth promoting rhizobacteria (PGPR) were isolated from common bean nodules from Nakuru County in...

Minute 3. New taxa. New taxa described since the last meeting on 4 July 2001 are Bradyrhizobium yuanmingense Yao et al. [Int J Syst Evol Microbiol 52 (2002), 2219–2230], Bradyrhizobium betae Rivas et al. [Int J Syst Evol Microbiol 54 (2004), 1271–1275], Rhizobium indigoferae Wei et al. [Int J Syst Evol Microbiol 52 (2002), 2231–2239], Rhizobium loessense Wei et al. [Int J Syst Evol Microbiol 53...

In order to screen the strains with Potassium and phosphorus-releasing bacteria from soil, potassium-dissolving medium was used for preliminary screening, transparent circle method re-screening. The content of soluble potassium determined by sodium tetraphenylborate method, phosphorus anticolorimetric molybdenum antimony. were identified morphological, biochemical molecular biology. results sho...

We compared the nodulation competitiveness of three strains of Rhizobium leguminosarum by counting the number of nodules formed on faba bean plants after the application at sowing time of different concentrations of the strains to soils already containing Rhizobium strains of the same species. A relationship of type y = ax was found to exist between the ratio of the nodules formed by the applie...

Rhizobium-legume symbiosis begins with two free living organisms, and ends with an intimate cellular co-existence. Rhizobium bacteria recognize specific plants, provoke development of a root nodule, and invade the plant tissue. Eventually, the Rhizobium cell transfers itself into a host cell, surrounds itself with plant membrane, and arranges a nutrient exchange in which the bacteria brings fix...

A glyceollin I accumulation o f about 6000 pmol • mg dry weight, a tenfold increase above control root tissue, was found in one type o f nodule from Glycine max which had been infected with a fix~ strain (61-A-24) o f Rhizobium japonicum. In nodules infected with one other ineffective (ßx~) strain o f Rhizobium japonicum (RH 31-Marburg) or with two f i x + strains o f Rhizobium japonicum (61 -A...