Complete genome sequence of the Medicago microsymbiont Ensifer (Sinorhizobium) medicae strain WSM419

Ensifer (Sinorhizobium) medicae is an effective nitrogen fixing microsymbiont of a diverse range of annual Medicago (medic) species. Strain WSM419 is an aerobic, motile, non-spore forming, Gram-negative rod isolated from a M. murex root nodule collected in Sardinia, Italy in 1981. WSM419 was manufactured commercially in Australia as an inoculant for annual medics during 1985 to 1993 due to its nitrogen fixation, saprophytic competence and acid tolerance properties. Here we describe the basic features of this organism, together with the complete genome sequence, and annotation. This is the first report of a complete genome sequence for a microsymbiont of the group of annual medic species adapted to acid soils. We reveal that its genome size is 6,817,576 bp encoding 6,518 protein-coding genes and 81 RNA only encoding genes. The genome contains a chromosome of size 3,781,904 bp and 3 plasmids of size 1,570,951, 1,245,408 and 219,313 bp. The smallest plasmid is a feature unique to this medic microsymbiont.

Complete genome sequence of rhizobium leguminosarum bv. trifolii strain WSM1325, an effective microsymbiont of annual Mediterranean clovers

Rhizobium leguminosarum bv trifolii is a soil-inhabiting bacterium that that has the capacity to be an effective nitrogen fixing microsymbiont of a diverse range of annual Trifolium (clover) species. Strain WSM1325 is an aerobic, motile, non-spore forming, Gram-negative rod isolated from root nodules collected in 1993 from the Greek Island of Serifos. WSM1325 is manufactured commercially in Australia as an inoculant for a broad range of annual clovers of Mediterranean origin due to its superior attributes of saprophytic competence, nitrogen fixation and acid-tolerance. Here we describe the basic features of this organism, together with the complete genome sequence, and annotation. This is the first completed genome sequence for a microsymbiont of annual clovers. We reveal that its genome size is 7,418,122 bp encoding 7,232 protein-coding genes and 61 RNA-only encoding genes. This multipartite genome contains 6 distinct replicons; a chromosome of size 4,767,043 bp and 5 plasmids of size 828,924, 660,973, 516,088, 350,312 and 294,782 bp.

Enhanced early nodulation of medicago truncatula co-inoculated with sinorhizobium medicae and achromobacter xylosoxidans

Efforts to increase the productivity and sustainability of agro-ecosystems have resulted in increased research focused on generating improved microbiological inoculant technologies. Plant growth-promoting rhizobacteria (PGPR) are one area receiving increased attention due to their potential for use as biofertilizers, plant-growth promoters, and biocontrol agents for weed and disease control in farming systems (Siddiqui, 2006).

Genome sequence of the Lotus spp. microsymbiont Mesorhizobium loti strain R7A

Mesorhizobium loti strain R7A was isolated in 1993 in Lammermoor, Otago, New Zealand from a Lotus corniculatus root nodule and is a reisolate of the inoculant strain ICMP3153 (NZP2238) used at the site. R7A is an aerobic, Gram-negative, non-spore-forming rod. The symbiotic genes in the strain are carried on a 502-kb integrative and conjugative element known as the symbiosis island or ICEMlSym(R7A). M. loti is the microsymbiont of the model legume Lotus japonicus and strain R7A has been used extensively in studies of the plant-microbe interaction. This report reveals that the genome of M. loti strain R7A does not harbor any plasmids and contains a single scaffold of size 6,529,530 bp which encodes 6,323 protein-coding genes and 75 RNA-only encoding genes. This rhizobial genome is one of 100 sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project.

Potential for agricultural production on disturbed soils mined for apatite using legumes and beneficial microbe

Christmas Island has been mined for rock phosphate for over 100 years, and as mining will finish in the next few decades there is a need to develop alternative economies on the island, such as high value crop production. However, to conserve the unique flora and fauna on the island, only land previously mined will be considered for this purpose. As these soils have been severely perturbed by mining, strategies to improve soil quality parameters need to be undertaken before plant based industries can be considered. For instance, legumes and beneficial microbes have demonstrated a positive role in the remediation of degraded soils. Therefore, this study aimed to establish the scientific basis upon which agriculture can effectively be developed on s oils post phosphate mining. Six legume species (Glycine max (Soybean), Vigna radiata (Mungbean), V. unguiculata (Cowpea), Phaseolus vulgaris (Navybean), Cajanus cajan (Pigeon pea), and Lablab purpureus (Lablab)) were sown onto a two ha rehabilitated site t hat had previously been mined for rock phosphate. The soil had a pH of 7.0, and was high in P but low in Bo, Cu, K, Mg, N and S and had low organic C. The legumes were inoculated with their respective rhizobial inoculant or co-inoculated with the rhizobia and a plant growth promoting bacteria (PGPB) at three different fertilizer rates (nil, a low rate, and five times the low rate). With the exception of P. vulgaris, all the legume species survived. The application of fertilizer was essential for maximum biomass yields 18 weeks after sowing, however the lower fertilizer rate was sufficient to obtain maximum yields for some cultivars. The PGPB increased yields and nodulation of some of the legumes at different fertilizer levels. Although the legumes (except P. vulgaris) grew in the Christmas Island environment, selection of appropriate legume cultivars and inoculants plus optimization of the fertilizer regime is required for reliable agricultural productivity on the island.

Molecular identification and characterization of phosphate solubilizing pseudomonas sp. isolated from rhizosphere of mash bean (Vigna mungo L.) for growth promotion in wheat

Bio-inoculants have potential role in plant growth promotion. The present study evaluated the potential of Pseudomonas strains as bio-inoculants in wheat on the basis of plant growth promotion and physiological characterization. The 16S rRNA gene sequencing and phylogenetic analysis revealed that four isolated strains belonged to genus Pseudomonas. These strains were positive for phosphorus solubilization and indole acetic acid production, whereas only two strains were positive candidate for their nitrogen fixing ability as determined by presence or absence of nifH gene through amplification from polymerase chain reaction. The pot experiment showed that the integrated use of Pseudomonas strains as co-inoculant and 50% applied mineral fertilizers enhanced the maximum wheat growth and development from 58 to 140% for different shoot and root growth parameters. The strain NCCP-45 and NCCP-237 were closely related to Pseudomonas beteli and Pseudomonas lini, respectively. These isolated strains can be used to increase crop productivity by using as a bio-fertilizer inoculum.