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Variation in mitogenome structural conformation in wild and cultivated lineages of sorghum corresponds with domestication history and plastome evolution
Get PDFMitochondria are organelles within eukaryotic cells that are central to the metabolic processes of cellular respiration and ATP production. However, the evolution of mitochondrial genomes (mitogenomes) in plants is virtually unknown compared to animal mitogenomes or plant plastids, due to complex structural variation and long stretches of repetitive DNA making accurate genome assembly more challenging. Comparing the structural and sequence differences of organellar genomes within and between sorghum species is an essential step in understanding evolutionary processes such as organellar sequence transfer to the nuclear genome as well as improving agronomic traits in sorghum related to cellular metabolism
Improving the outcomes of using canid pest ejectors to manage wild dogs in peri-urban environments
No full textThe use of lethal control techniques to mitigate the impacts of wild dogs (Canis familiaris), particularly in urban environments, can be complex and is often influenced by a variety of external factors. However, wild dog control is sometimes necessary for the prevention of, or in response to, negative impacts to livestock, native wildlife, pets, and people. Canid pest ejectors (CPEs) were registered for use in Australia in 2016 and are available for the control of peri-urban wild dogs, using either PAPP or 1080 toxin, where regulations permit. To understand and improve deployment strategies, we assessed wild dog, fox, and non-target species interactions with CPEs in peri-urban regions. Using modelling techniques, we determined when and how often GPS-tracked wild dogs would have encountered CPEs when deployed at varying densities. Then, field trials were conducted with CPEs deployed continuously for twelve months across five sites on the Sunshine Coast or Gympie regions. Interactions and activations of CPEs were monitored with camera traps. Finally, a CPE capsule toxin degradation trial was conducted to determine if 1080 and PAPP capsules remained sufficiently toxic when not activated and continually deployed over a two-year period. This paper will provide a brief overview of the results of these trials, including assessments of target and non-target species interactions with CPEs, and discuss recommended deployment strategies for their optimal and safe use
Optimising control of invasive cactus using biological control
No full textInvasive opuntioid cacti pose significant impacts to the environment, agriculture, and recreation in Australia. The cochineal insects, Dactylopius spp., are effective biological control agents for a number of invasive cacti species in Australia, e.g., Dactylopius opuntiae ‘US’ lineage on Opuntia stricta, D. opuntiae ‘Mexico’ lineage on O. robusta, D. ceylonicus on O. monacantha, and D. austrinus on O. aurantiaca. Studies have found that these agents might also be suitable for control of some emerging invasive cacti. Dactylopius austrinus and D. ceylonicus have relatively narrow host ranges, whereas both D. opuntiae lineages feed and develop on a wider number of cactus species. Routine post-release field surveys of D. opuntiae lineages on O. tomentosa revealed biotic interactions that provide potential explanations for why the cochineal is generally not as effective on larger tree-form cacti. The presence of a predatory ant, Crematogaster spp., was often associated with poor establishment and low population build-up of the cochineal. Other significant predators include the “mealybug destroyer” Cryptolaemus montrouzieri and several Neuropteran species. The cactus longhorn beetle, Lagocheirus funestus, was rediscovered at one field site where it was observed causing significant damage to O. tomentosa. The rediscovery of this agent and its observed impact in the field, suggests its rearing and redistribution could complement cochineal biological control of O. tomentosa
A new sex-specific genetic marker (fshr 1834G>T) for flathead grey mullet, Mugil cephalus, in Queensland, Australia
Get PDFIn this study, genetic sex marker candidates from northern hemisphere Mugil cephalus were tested to see if they could be used to sex a population originating from south-east Queensland, Australia. As such, a region of the follicle stimulating hormone receptor (fshr) gene was sequenced but did not contain previously published single nucleotide polymorphisms (SNPs). However, further screening of the sequenced fshr region revealed a promising sex marker candidate for Queensland M. cephalus, fshr 1834 G>T, which was accurate in 100% of fish tested (excluding intersex fish, which had the female genotype). While all females tested were homozygous G/G, males presented as either G/T (common) or T/T (lower frequency). Subsequently, a real-time high-resolution melt was developed to facilitate rapid and accurate genotyping of M. cephalus based on the fshr 1834 G>T SNP. Initial results suggest that fshr 1834 G>T is a useful SNP that can reduce the need for more invasive sampling techniques such as gonadal biopsy, provide information relating to the sex of captive stock prior to gonadal maturation, and may prove useful in wild population surveys and stock assessment
Promotor insertion leads to polyembryony in mango – a case of convergent evolution with citrus
Get PDFSexual reproduction in plants is the main pathway for creating new genetic combinations in modern agriculture. In heterozygous plants, after the identification of a plant with desired traits, vegetative propagation (cloning) is the primary path to create genetically uniform plants. Another natural plant mechanism that creates genetically uniform plants (clones) is apomixis. In fruit crops like citrus and mango, sporophytic apomixis results in polyembryony, where seeds contain multiple embryos, one is sexually originated and the others are vegetative clones of the parent mother tree. Utilizing the mango genome and genetic analysis of a diverse germplasm collection, we identified MiRWP as the gene that causes polyembryony in mango. There is a strong correlation between a specific insertion in the gene’s promoter region and altered expression in flowers and developing fruitlets, inducing multiple embryos. The MiRWP gene is an ortholog of CitRWP that causes polyembryony in citrus. Based on the data, we speculate that promoter insertion events, which occurred independently in citrus and mango, induced nucellar embryogenesis. The results suggest convergent evolution of polyembryony in the two species. Further work is required to demonstrate the utility of these genes (mango and citrus) in other biological systems as a tool for the clonal production of other crops
Domestication through clandestine cultivation constrained genetic diversity in magic mushrooms relative to naturalized populations
No full textSummary Fungi that are edible or fermentative were domesticated through selective cultivation of their desired traits. Domestication is often associated with inbreeding or selfing, which may fix traits other than those under selection, and causes an overall decrease in heterozygosity. A hallucinogenic mushroom, Psilocybe cubensis, was domesticated from its niche in livestock dung for production of psilocybin. It has caused accidental poisonings since the 1940s in Australia, which is a population hypothesized to be introduced from an unknown center of origin. We sequenced genomes of 38 isolates from Australia and compared them with 86 genomes of commercially available cultivars to determine (1) whether P. cubensis was introduced to Australia, and (2) how domestication has impacted commercial cultivars. Our analyses of genome-wide SNPs and single-copy orthologs showed that the Australian population is naturalized, having recovered its effective population size after a bottleneck when it was introduced, and it has maintained relatively high genetic diversity based on measures of nucleotide and allelic diversity. In contrast, domesticated cultivars generally have low effective population sizes and hallmarks of selfing and clonal propagation, including low genetic diversity, low heterozygosity, high linkage disequilibrium, and low allelic diversity of mating-compatibility genes. Analyses of kinship show that most cultivars are founded from related populations. Alleles in the psilocybin gene cluster are identical across most cultivars of P. cubensis with low diversity across coding sequence; however, unique allelic diversity in Australia and some cultivars may translate to differences in biosynthesis of psilocybin and its analogs
Climatic influences on post-release populations of the biological control agent Cecidochares connexa in northern Queensland
Get PDFCecidochares connexa, stem-galling fly, is Australia’s only mass-reared and released biological control agent for the invasive weed species, Chromolaena odorata (Siam weed). Releases of C. connexa commenced in late 2019 in northern Queensland and have now covered eight Local Government Areas. In this paper we will assess the gall infection rate of C. connexa, at two trial sites within two different climatic zones over several years. One site is within the wet tropics (Nyleta Hill), with a mean annual rainfall of 3,294 mm and the other site is situated in the dry tropics (Black River), with mean annual rainfall of 1,135 mm. All climatic parameters were analysed, with strong positive correlations existing between an increase in rainfall and gall infection rate (galls versus growing tips). Black River experienced an increase of C. connexa galls by 2,428% in early 2023, compared to the previous years. This was due to the site receiving double the amount of rainfall than the previous year (1,844 mm) in the same period. These boom-and-bust rainfall events in the dry tropics compared to a constant supply of moisture in the wet tropics creates different plant and agent responses
Double-stranded RNA prevents and cures infection by rust fungi
Get PDFFungal pathogens that impact perennial plants or natural ecosystems require management strategies beyond fungicides and breeding for resistance. Rust fungi, some of the most economically and environmentally important plant pathogens, have shown amenability to double-stranded RNA (dsRNA) mediated control. To date, dsRNA treatments have been applied prior to infection or together with the inoculum. Here we show that a dsRNA spray can effectively prevent and cure infection by Austropuccinia psidii (cause of myrtle rust) at different stages of the disease cycle. Significant reductions in disease coverage were observed in plants treated with dsRNA targeting essential fungal genes 48 h pre-infection through to 14 days post-infection. For curative treatments, improvements in plant health and photosynthetic capacity were seen 2–6 weeks post-infection. Two-photon microscopy suggests inhibitory activity of dsRNA on intercellular hyphae or haustoria. Our results show that dsRNA acts both preventively and curatively against myrtle rust disease, with treated plants recovering from severe infection. These findings have immediate potential in the management of the more than 10-year epidemic of myrtle rust in Australia
Feeding Leucaena to manage the rumen for maximum beef profit
No full textLeucaena leucocephala, a perennial browse legume, represents one of the few nutritional options to significantly improve beef productivity in northern Australia. This project used expert knowledge and existing spatial data sets to map potential distribution in Queensland, the Northern Territory, and northern Western Australia, estimating that up to 27.3M hectares of land in Northern Australia could viably support Leucaena-grass pasture grazing systems. This included 4.6M hectares in humid coastal areas of Queensland that are suitable for the psyllid-resistant Redlands cultivar, with economic analysis of further adoption suggesting a total benefit of $61-123M over the next 40 years across northern Australia.
To maximise the benefits for cattle grazing Leucaena, the cattle need rumen bacteria capable of degrading the toxins mimosine, 3,4 DHP and 2,3 DHP. This project investigated the effect of the Redlands cultivar on the current DAF inoculum resulting in the development of a new mixed bacterial inoculum (TriMix), adapted for better utilisation of the three different Leucaena cultivars, Redlands, Wondergraze and Cunningham. An on-property survey of the presence of de-toxifying bacteria in the rumen found that cattle which had never been exposed to Leucaena did not possess rumen bacteria able to degrade the toxins 3,4 DHP and 2,3 DHP so would benefit from receiving the Department of Agriculture and Fisheries Leucaena inoculum if being moved to a Leucaena-grass pasture grazing system
Emergency animal disease (EAD) response arrangements in Australia
No full textAustralia’s EAD response arrangements have been assessed as comprehensive and well-understood by system participants. These arrangements support planning for EAD response readiness, and decision-making within a response. Should we face an EAD incident involving feral pigs in future, emergency response decision-making will be dependent upon the specific scenario and informed by available scientific data and on ground expertise. This presentation will outline the approach to an EAD response from a Chief Veterinary Officer’s perspective, including relevant considerations about feral pigs