Diversity and evolution of rice progenitors in Australia.

In the thousands of years of rice domestication in Asia, many useful genes have been lost from the gene pool. Wild rice is a key source of diversity for domesticated rice. Genome sequencing has suggested that the wild rice populations in northern Australia may include novel taxa, within the AA genome group of close (interfertile) wild relatives of domesticated rice that have evolved independently due to geographic separation and been isolated from the loss of diversity associated with gene flow from the large populations of domesticated rice in Asia. Australian wild rice was collected from 27 sites from Townsville to the northern tip of Cape York. Whole chloroplast genome sequences and 4,555 nuclear gene sequences (more than 8 Mbp) were used to explore genetic relationships between these populations and other wild and domesticated rices. Analysis of the chloroplast and nuclear data showed very clear evidence of distinctness from other AA genome Oryza species with significant divergence between Australian populations. Phylogenetic analysis suggested the Australian populations represent the earliest-branching AA genome lineages and may be critical resources for global rice food security. Nuclear genome analysis demonstrated that the diverse O. meridionalis populations were sister to all other AA genome taxa while the Australian O. rufipogon-like populations were associated with the clade that included domesticated rice. Populations of apparent hybrids between the taxa were also identified suggesting ongoing dynamic evolution of wild rice in Australia. These introgressions model events similar to those likely to have been involved in the domestication of rice.

High-throughput sequencing and mutagenesis to accelerate the domestication of Microlaena stipoides as a new food crop.

Global food demand, climatic variability and reduced land availability are driving the need for domestication of new crop species. The accelerated domestication of a rice-like Australian dryland polyploid grass, Microlaena stipoides (Poaceae), was targeted using chemical mutagenesis in conjunction with high throughput sequencing of genes for key domestication traits. While M. stipoides has previously been identified as having potential as a new grain crop for human consumption, only a limited understanding of its genetic diversity and breeding system was available to aid the domestication process. Next generation sequencing of deeply-pooled target amplicons estimated allelic diversity of a selected base population at 14.3 SNP/Mb and identified novel, putatively mutation-induced polymorphisms at about 2.4 mutations/Mb. A 97% lethal dose (LD97) of ethyl methanesulfonate treatment was applied without inducing sterility in this polyploid species. Forward and reverse genetic screens identified beneficial alleles for the domestication trait, seed-shattering. Unique phenotypes observed in the M2 population suggest the potential for rapid accumulation of beneficial traits without recourse to a traditional cross-breeding strategy. This approach may be applicable to other wild species, unlocking their potential as new food, fibre and fuel crops.

Comparison of injury incidences between football teams playing in different climatic regions.

Australian Football League (AFL) teams in northern (warmer) areas generally have higher rates of injury than those in southern (cooler) areas. Conversely, in soccer (football) in Europe, teams in northern (cooler) areas have higher rates of injury than those in southern (warmer) areas, with an exception being knee anterior cruciate ligament (ACL) injuries, which are more common in the southern (warmer) parts of Europe. This study examined relative injury incidence in the AFL comparing 9,477 injuries over 229,827 player-weeks from 1999-2012. There was a slightly higher injury incidence for teams from warmer parts of Australia (relative risk [RR] 1.05, 95% confidence interval [CI] 1.01-1.10) with quadriceps strains (RR 1.32, 95% CI 1.10-1.58), knee cartilage injuries (RR 1.42, 95% CI 1.16-1.74), and ankle sprains (RR 1.17, 95% CI 1.00-1.37) all being more likely in warmer region teams. Achilles injuries followed a reverse pattern, tending to be more common in cooler region teams (RR 0.70, 95% CI 0.47-1.03). In conclusion, common findings from the AFL and European soccer are that ankle sprains and ACL injuries are generally more likely in teams playing in warmer climate zones, whereas Achilles tendinopathy may be more likely in teams playing in cooler zones. These injuries may have climate or surface risk factors (possibly related to types and structure of grass and shoe-surface traction) that are universal across different football codes.

Analysis of adaptive ribosomal gene diversity in wild plant populations from contrasting climatic environments.

Plant populations may contain variation that reflects adaptation to local environmental conditions. Clues to adaptive evolution of plants may be found in the genomes of species growing in diverse environments or across steep environmental gradients, and under stress. We have examined populations of wild relatives of barley and rice across diverse environmental gradients. Greater diversity, in a nuclear biotic stress defense gene and in chloroplast genes, was found in the more stressed, hotter and dryer environments. This may reflect the greater heterogeneity of these environments. Adaptation of plants to different abiotic stresses (temperatures and levels of water availability) may also require significant adaptation to the different biotic (pest and disease) pressures in these environments.

Genome diversity in wild grasses under environmental stress.

Patterns of diversity distribution in the Isa defense locus in wild-barley populations suggest adaptive selection at this locus. The extent to which environmental selection may act at additional nuclear-encoded defense loci and within the whole chloroplast genome has now been examined by analyses in two grass species. Analysis of genetic diversity in wild barley (Hordeum spontaneum) defense genes revealed much greater variation in biotic stress-related genes than abiotic stress-related genes. Genetic diversity at the Isa defense locus in wild populations of weeping ricegrass [Microlaena stipoides (Labill.) R. Br.], a very distant wild-rice relative, was more diverse in samples from relatively hotter and drier environments, a phenomenon that reflects observations in wild barley populations. Whole-chloroplast genome sequences of bulked weeping ricegrass individuals sourced from contrasting environments showed higher levels of diversity in the drier environment in both coding and noncoding portions of the genome. Increased genetic diversity may be important in allowing plant populations to adapt to greater environmental variation in warmer and drier climatic conditions.

Characterizing homologues of crop domestication genes in poorly described wild relatives by high-throughput sequencing of whole genomes.

Wild crop relatives represent a source of novel alleles for crop genetic improvement. Screening biodiversity for useful or diverse gene homologues has often been based upon the amplification of targeted genes using available sequence information to design primers that amplify the target gene region across species. The crucial requirement of this approach is the presence of sequences with sufficient conservation across species to allow for the design of universal primers. This approach is often not successful with diverse organisms or highly variable genes. Massively parallel sequencing (MPS) can quickly produce large amounts of sequence data and provides a viable option for characterizing homologues of known genes in poorly described genomes. MPS of genomic DNA was used to obtain species-specific sequence information for 18 rice genes related to domestication characteristics in a wild relative of rice, Microlaena stipoides. Species-specific primers were available for 16 genes compared with 12 genes using the universal primer method. The use of species-specific primers had the potential to cover 92% of the sequence of these genes, while traditional universal primers could only be designed to cover 80%. A total of 24 species-specific primer pairs were used to amplify gene homologues, and 11 primer pairs were successful in capturing six gene homologues. The 23 million, 36-base pair (bp) paired end reads, equated to an average of 2X genome coverage, facilitated the successful amplification and sequencing of six target gene homologues, illustrating an important approach to the discovery of useful genes in wild crop relatives.

A Hypothesis: Could Portable Natural Grass be a Risk Factor for Knee Injuries?

Previous study has shown a likely link between increased shoe- surface traction and risk of knee Anterior Cruciate Ligament (ACL) injury. Portable natural grass systems are being used more often in sport, but no study to date has investigated their relative safety. By their nature, they must have high resistance to falling apart and therefore newly laid systems may be at risk of creating excessive shoe-surface traction. This study describes two clusters of knee injuries (particularly non-contact ACL injuries), each occurring to players of one professional football team at single venue, using portable grass, in a short space of time. The first series included two ACL injuries, one posterolateral complex disruption and one lateral ligament tear occurring in two rugby league games on a portable bermudagrass surface in Brisbane, Australia. The second series included four non-contact ACL injuries over a period of ten weeks in professional soccer games on a portable Kentucky bluegrass/perennial ryegrass surface in Barcelona, Spain. Possible intrinsic risk factors are discussed but there was no common risk shared by the players. Although no measures of traction were made at the Brisbane venue, average rotational traction was measured towards the end of the injury cluster at Camp Nou, Barcelona, to be 48 Nm. Chance undoubtedly had a part to play in these clusters, but the only obvious common risk factor was play on a portable natural grass surface soon after it was laid. Further study is required to determine whether portable natural grass systems may exhibit high shoe-surface traction soon after being laid and whether this could be a risk factor for knee injury. Key pointsExcessive shoe-surface traction is a hypothesised risk factor for knee ligament injuries, including anterior cruciate ligament injuries.Portable natural grass systems (by their nature in order to prevent grass rolls or squares from falling apart) will tend to exhibit high resistance to tearing when first laid. This may lead to excessive shoe-surface traction.This dual case series describes two clusters of non-contact knee ligament injuries which occurred in circumstances of newly laid portable turf.Further research is warranted to undercover any link between non-contact knee ligament injuries and ground surfaces conditions.

Enzyme-immunoassay for the determination of metallothionein in human urine: application to environmental monitoring.

The objectives of this study were to develop an enzyme immunoassay for metallothioneins in human urine using a polyclonal antiserum and to demonstrate a possible relationship between the level of this biomarker and heavy metal exposure. The antiserum was raised in sheep against horse metallothionein conjugated to carboxylated bovine serum albumin. The antibody was used to construct a two-step competitive ELISA procedure. Human urine was treated with activated charcoal powder to remove traces of metallothioneins and known amounts of pure metallothioneins were added to provide standards for a standard curve. Metallothionein levels were measured in two groups of children living in areas of mild and high environmental pollution due mainly to heavy metals. A comparison was made between the biomarker levels and the levels of cadmium and lead in urine samples in the two groups. A group of children from a non-polluted area acted as controls. The results show that the detected levels of metallothioneins appear to correspond to levels of the two heavy metals studied and that there was an apparent relationship to the environmental exposure. Thus according to results of this study the increase in the metallothionein excretion seems to provide an indication of previous of exposure to metals. The ELISA procedure is sensitive and robust and can be used to screen large numbers of samples and is more rapid than the physical procedures currently used for analysis of these proteins. The assay can therefore be used as an additional tool for screening at-risk populations where either environmental or occupational exposure to divalent heavy metals is suspected.