Selecting improved Lotus nodulating rhizobia to expedite the development of new forage species

Aims In the past decades the increasing focus by Australian pasture development programs on the genus Lotus has seen the evaluation of many species previously untested in Australia. In field trials, nodulation failure was commonplace. This work was undertaken to select effective symbionts for Lotus to ensure further agronomic evaluation of the genus was not compromised. The symbiotic needs of Lotus ornithopodioides were a particular focus of the studies. Methods Glasshouse experiments were undertaken to evaluate symbiotic relationships between 15 Lotus spp and 23 strains of nodulating Mesorhizobium loti. This was followed by evaluation of elite rhizobial strains for their ability to persist and form nodules under field conditions. Results Complex symbiotic interactions were recorded between strains of lotus rhizobia and the different species of Lotus. Notably, the rhizobia that are currently provided commercially in Australia for the inoculation of Lotus corniculatus (strain SU343) and Lotus uliginosus (strain CC829) did not form effective symbioses with the promising species L. ornithopodioides and L. maroccanus. No strain we evaluated was compatible with all the Lotus species, however several strains with a broad host range were identified. WSM1293 and WSM1348 were the most effective strains on L. ornithopodioides and L. peregrinus.These strains were also moderately effective on L. corniculatus (79 and 52% of SU343), less effective on L. maroccanus (26 and 49% of SRDI110) but were ineffective on L. uliginosus. The latter species overall had very specific rhizobial needs. Both WSM1293 and WSM1348 produced adequate levels of nodulation when inoculated on L. ornithopodioides, over two seasons at three field sites. Conclusions Effective and persistent strains are now available that should allow the un-compromised evaluation of many of the contemporary Lotus species in the field. Selecting a strain for use in commercial inoculants will be more problematic, given the very large host-strain interactions for nitrogen fixation. Here, the balance of Lotus species which are adopted by farmers will have a strong bearing on which rhizobial strains are progressed to commerce

Influence of mowing frequency and mower sharpness on efficiency of PSII and antioxidant and carbohydrate metabolism of creeping bentgrass

Sports fields are mown primarily to provide a uniform surface for ball roll and bounce. However, mowing creates openings that facilitate water loss and entry points for pathogens, and increases susceptibility to other stresses. The objectives of our research were to identify physiological mechanisms that allow creeping bentgrass to tolerate close and frequent mowing. Plants often increase formation of reactive oxygen species (ROS) in response to wounding. Accumulation of ROS may damage macromolecules such as lipids, proteins, and nucleic acids. Damage to these macromolecules may result in reduced plant growth and vigor, or even death. Plants form enzymes to quench ROS and protect cells from oxidative damage. However, activities of ROS-scavenging enzymes often are reduced during stress. In our research, activities of the ROS-quenching enzymes catalase and ascorbate peroxidase were reduced in mowed grasses. Reduced activities of these enzymes may result in accumulation of ROS. However, no differences were observed in levels of lipid peroxidation between not-cut and mowed grasses, indicating that accumulation of ROS was not sufficient to cause severe oxidative stress. Although toxic at high concentrations, ROS may act as a component of a signal transduction pathway that acclimates not-stressed tissue to potential stress. It is necessary for grasses to regrow leaf tissue removed by mowing. Reserve carbohydrates often are hydrolyzed to generate carbon for respiration and to provide substrates for development of leaf and shoot tissue. Creeping bentgrass forms fructans as reserve carbohydrates. In our research, fructans were reduced in mown grasses compared to not-cut grasses. Glucose levels also were reduced in mowed grasses compared to not-cut grasses. Glucose likely was oxidized in the glycolytic pathway and respiration to provide energy for formation of new leaf tissue. It is important to remember that mowing is a stress and that mowing programs should balance agronomic requirements of grasses with sports play demands in order to produce uniform and visually appealing turf that is vigorous in growth

Effects of ethephon on growth and morphology of perennial grasses

In 1880, von Sachs first popularized the concept of chemical messengers that were synthesized by the plant and then translocated throughout it to control the growth and formation of plant organs. However, it was not until1926 that Went isolated a growth-promoting chemical messenger from oat (Avena sativa L.) coleoptiles. This was the first naturally occurring plant growth regulator (PGR) to be isolated, and it later was named auxin by Kogl and Haagen-Smit in 1931 (Taiz and Zeiger, 1991). A PGR is an organic compound that is active at low concentrations

Psychodrama as a Personal Growth Experience : A programme for Teacher Trainees

Churchlands College was established in 1972 and was drawing up its first course submission when legislation separating teacher training institutions from the State Government Education Department was passed. With autonomy from the outset, staff were able to plan courses consistent with their own values and expertise. The College as a whole adopted a three-pronged approach to teacher preparation with programmes in curriculum and instruction methods, education and educational psychology and in personal and professional growth and development. Each department considered its possible contribution to these streams. I n considering its contribution to the personal growth programme for trainees the Psychology Department was in sympathy with recent trends in teacher education which focussed on the facilitative skills of the teacher and particularly on his ability to interrelate with his classroom group

Genome sequence of the Lebeckia ambigua-nodulating 'Burkholderia sprentiae' strain WSM5005T

"Burkholderia sprentiae" strain WSM5005(T) is an aerobic, motile, Gram-negative, non-sporeforming rod that was isolated in Australia from an effective N-2-fixing root nodule of Lebeckia ambigua collected in Klawer, Western Cape of South Africa, in October 2007. Here we describe the features of "Burkholderia sprentiae" strain WSM5005T, together with the genome sequence and its annotation. The 7,761,063 bp high-quality-draft genome is arranged in 8 scaffolds of 236 contigs, contains 7,147 protein-coding genes and 76 RNA-only encoding genes, and is one of 20 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Community Sequencing Program

Genome sequence of <i>Ensifer medicae</i> strain WSM1369; an effective microsymbiont of the annual legume <i>Medicago sphaerocarpos</i>

Ensifer medicae WSM1369 is an aerobic, motile, Gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as a legume microsymbiont of Medicago. WSM1369 was isolated in 1993 from a nodule recovered from the roots of Medicago sphaerocarpos growing at San Pietro di Rudas, near Aggius in Sardinia (Italy). WSM1369 is an effective microsymbiont of the annual forage legumes M. polymorpha and M. sphaerocarpos. Here we describe the features of E. medicae WSM1369, together with genome sequence information and its annotation. The 6,402,557 bp standard draft genome is arranged into 307 scaffolds of 307 contigs containing 6,656 protein-coding genes and 79 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

High-quality permanent draft genome sequence of <i>Rhizobium sullae</i> strain WSM1592; a <i>Hedysarum coronarium</i> microsymbiont from Sassari, Italy

Rhizobium sullae strain WSM1592 is an aerobic, Gram-negative, non-spore-forming rod that was isolated from an effective nitrogen (N2) fixing root nodule formed on the short-lived perennial legume Hedysarum coronarium (also known as Sulla coronaria or Sulla). WSM1592 was isolated from a nodule recovered from H. coronarium roots located in Ottava, bordering Sassari, Sardinia in 1995. WSM1592 is highly effective at fixing nitrogen with H. coronarium, and is currently the commercial Sulla inoculant strain in Australia. Here we describe the features of R. sullae strain WSM1592, together with genome sequence information and its annotation. The 7,530,820 bp high-quality permanent draft genome is arranged into 118 scaffolds of 118 contigs containing 7.453 protein-coding genes and 73 RNA-only encoding genes. This rhizobial genome is sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project

Genome sequence of the Ornithopus/Lupinus-nodulating Bradyrhizobium sp. strain WSM471

Bradyrhizobium sp. strain WSM471 is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from an effective nitrogen-(N-2) fixing root nodule formed on the annual legume Ornithopus pinnatus (Miller) Druce growing at Oyster Harbour, Albany district, Western Australia in 1982. This strain is in commercial production as an inoculant for Lupinus and Ornithopus. Here we describe the features of Bradyrhizobium sp. strain WSM471, together with genome sequence information and annotation. The 7,784,016 bp high-quality-draft genome is arranged in 1 scaffold of 2 contigs, contains 7,372 protein-coding genes and 58 RNA-only encoding genes, and is one of 20 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Community Sequencing Program

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.<br /