SnTox3 Acts in Effector Triggered Susceptibility to Induce Disease on Wheat Carrying the Snn3 Gene

The necrotrophic fungus Stagonospora nodorum produces multiple proteinaceous host-selective toxins (HSTs) which act in effector triggered susceptibility. Here, we report the molecular cloning and functional characterization of the SnTox3-encoding gene, designated SnTox3, as well as the initial characterization of the SnTox3 protein. SnTox3 is a 693 bp intron-free gene with little obvious homology to other known genes. The predicted immature SnTox3 protein is 25.8 kDa in size. A 20 amino acid signal sequence as well as a possible pro sequence are predicted. Six cysteine residues are predicted to form disulfide bonds and are shown to be important for SnTox3 activity. Using heterologous expression in Pichia pastoris and transformation into an avirulent S. nodorum isolate, we show that SnTox3 encodes the SnTox3 protein and that SnTox3 interacts with the wheat susceptibility gene Snn3. In addition, the avirulent S. nodorum isolate transformed with SnTox3 was virulent on host lines expressing the Snn3 gene. SnTox3-disrupted mutants were deficient in the production of SnTox3 and avirulent on the Snn3 differential wheat line BG220. An analysis of genetic diversity revealed that SnTox3 is present in 60.1% of a worldwide collection of 923 isolates and occurs as eleven nucleotide haplotypes resulting in four amino acid haplotypes. The cloning of SnTox3 provides a fundamental tool for the investigation of the S. nodorum-wheat interaction, as well as vital information for the general characterization of necrotroph-plant interactions.This work was supported by USDA-ARS CRIS projects 5442-22000-043-00D and 5442-22000-030-00D

The Egyptian wheat cultivar Gemmeiza-12 is a source of resistance against the fungus <i>Zymoseptoria tritici</i>

Background: Wheat is one of the world’s most important cereal crops. However, the fungal pathogen Zymoseptoria tritici can cause disease epidemics, leading to reduced yields. With climate change and development of new agricultural areas with suitable environments, Z. tritici may advance into geographical areas previously unaffected by this pathogen. It is currently unknown how Egyptian wheat will perform in the face of this incoming threat. This project aimed to assess the resistance of Egyptian wheat germplasm to Z. tritici, to identify cultivars with high levels of resistance and characterise the mechanism(s) of resistance present in these cultivars. Results: Eighteen Egyptian wheat cultivars were screened against two Z. tritici model isolates and exhibited a wide spectrum of responses. This ranged from resistance to complete susceptibility to one or both isolates tested. The most highly resistant cultivars from the initial screen were then tested under two environmental conditions against modern UK field isolates. Disease levels under UK-like conditions were higher, however, symptom development on the cultivar Gemmeiza-12 was noticeably slower than on other Egyptian wheats. The robustness of the resistance shown by Gemmeiza-12 was confirmed in experiments mimicking Egyptian environmental conditions, where degree of Z. tritici infection was lower. The Kompetitive allele-specific PCR (KASP) diagnostic assay suggested the presence of an Stb6 resistant allele in several Egyptian wheats including Gemmeiza-12. Infection assays using the IPO323 WT and IPO323ΔAvrStb6 mutant confirmed the presence of Stb6 in several Egyptian cultivars including Gemmeiza-12. Confocal fluorescence microscopy demonstrated that growth of the IPO323 strain is blocked at the point of stomatal penetration on Gemmeiza-12, consistent with previous reports of Stb gene mediated resistance. In addition to this R-gene mediated resistance, IPO323 spores showed lower adherence to leaves of Gemmeiza-12 compared to UK wheat varieties, suggesting other aspects of leaf physiology may also contribute to the resistance phenotype of this cultivar. Conclusion: These results indicate that Gemmeiza-12 will be useful in future breeding programs where improved resistance to Z. tritici is a priority

In utero exposure to HIV and/or antiretroviral therapy: a systematic review of preclinical and clinical evidence of cognitive outcomes

Introducion With the increasing number of children exposed to HIV or antiretroviral therapy in utero, there are concerns that this population may have worse neurodevelopmental outcomes compared to those who are unexposed. The objective of this study was to systematically review the clinical and preclinical literature on the effects of in utero exposure to HIV and/or antiretroviral therapy (ART) on neurodevelopment. Methods We systematically searched OVID Medline, PsycINFO and Embase, as well as the Cochrane Collaborative Database, Google Scholar and bibliographies of pertinent articles. Titles, abstracts, and full texts were assessed independently by two reviewers. Data from included studies were extracted. Results are summarized qualitatively. Results The search yielded 3027 unique titles. Of the 255 critically reviewed full-text articles, 25 met inclusion criteria for the systematic review. Five articles studied human subjects and looked at brain structure and function. The remaining 20 articles were preclinical studies that mostly focused on behavioural assessments in animal models. The few clinical studies had mixed results. Some clinical studies found no difference in white matter while others noted higher fractional anisotropy and lower mean diffusivity in the brains of HIV-exposed uninfected children compared to HIV-unexposed uninfected children, correlating with abnormal neurobehavioral scores. Preclinical studies focused primarily on neurobehavioral changes resulting from monotherapy with either zidovudine or lamivudine. Various developmental and behavioural changes were noted in preclinical studies with ART exposure, including decreased grooming, decreased attention, memory deficits and fewer behaviours associated with appropriate social interaction. Conclusions While the existing literature suggests that there may be some neurobehavioral differences associated with HIV and ART exposure, limited data are available to substantially support these claims. More research is needed comparing neurobiological factors between HIV-exposed uninfected and HIV-unexposed uninfected children and using exposures consistent with current clinical care

Multi-stage resistance to <i>Zymoseptoria tritici</i> revealed by GWAS in an Australian bread wheat diversity panel

Septoria tritici blotch (STB) has been ranked the third most important wheat disease in the world, threatening a large area of wheat production. Although major genes play an important role in the protection against Zymoseptoria tritici infection, the lifespan of their resistance unfortunately is very short in modern wheat production systems. Combinations of quantitative resistance with minor effects, therefore, are believed to have prolonged and more durable resistance to Z. tritici. In this study, new quantitative trait loci (QTLs) were identified that are responsible for seedling-stage resistance and adult-plant stage resistance (APR). More importantly was the characterisation of a previously unidentified QTL that can provide resistance during different stages of plant growth or multi-stage resistance (MSR). At the seedling stage, we discovered a new isolate-specific QTL, QSt.wai.1A.1. At the adult-plant stage, the new QTL QStb.wai.6A.2 provided stable and consistent APR in multiple sites and years, while the QTL QStb.wai.7A.2 was highlighted to have MSR. The stacking of multiple favourable MSR alleles was found to improve resistance to Z. tritici by up to 40%

Comparative Pathogenomics Reveals Horizontally Acquired Novel Virulence Genes in Fungi Infecting Cereal Hosts

Comparative analyses of pathogen genomes provide new insights into how pathogens have evolved common and divergent virulence strategies to invade related plant species. Fusarium crown and root rots are important diseases of wheat and barley world-wide. In Australia, these diseases are primarily caused by the fungal pathogen Fusarium pseudograminearum. Comparative genomic analyses showed that the F. pseudograminearum genome encodes proteins that are present in other fungal pathogens of cereals but absent in non-cereal pathogens. In some cases, these cereal pathogen specific genes were also found in bacteria associated with plants. Phylogenetic analysis of selected F. pseudograminearum genes supported the hypothesis of horizontal gene transfer into diverse cereal pathogens. Two horizontally acquired genes with no previously known role in fungal pathogenesis were studied functionally via gene knockout methods and shown to significantly affect virulence of F. pseudograminearum on the cereal hosts wheat and barley. Our results indicate using comparative genomics to identify genes specific to pathogens of related hosts reveals novel virulence genes and illustrates the importance of horizontal gene transfer in the evolution of plant infecting fungal pathogens

Placental glucocorticoid receptor isoforms in a sheep model of maternal allergic asthma

Maternal asthma increases the risk of adverse pregnancy outcomes and may affect fetal growth and placental function by differential effects on the expression of glucocorticoid receptor (GR) isoforms, leading to altered glucocorticoid signalling. Our aim was to examine the effect of maternal asthma on placental GR profiles using a pregnant sheep model of asthma. Nine known GR isoforms were detected. There was a significant increase in the expression of placental GR isoforms that are known to have low trans-activational activity in other species including GR A, GR P and GRγ which may result in a pro-inflammatory environment in the presence of allergic asthma

Further evidence for the involvement of EFL1 in a Shwachman-Diamond-like syndrome and expansion of the phenotypic features.

Recent evidence has implicated EFL1 in a phenotype overlapping Shwachman-Diamond syndrome (SDS), with the functional interplay between EFL1 and the previously known causative gene SBDS accounting for the similarity in clinical features. Relatively little is known about the phenotypes associated with pathogenic variants in the EFL1 gene, but the initial indication was that phenotypes may be more severe, when compared with SDS. We report a pediatric patient who presented with a metaphyseal dysplasia and was found to have biallelic variants in EFL1 on reanalysis of trio whole-exome sequencing data. The variant had not been initially reported because of the research laboratory's focus on de novo variants. Subsequent phenotyping revealed variability in her manifestations. Although her metaphyseal abnormalities were more severe than in the original reported cohort with EFL1 variants, the bone marrow abnormalities were generally mild, and there was equivocal evidence for pancreatic insufficiency. Despite the limited number of reported patients, variants in EFL1 appear to cause a broader spectrum of symptoms that overlap with those seen in SDS. Our report adds to the evidence of EFL1 being associated with an SDS-like phenotype and provides information adding to our understanding of the phenotypic variability of this disorder. Our report also highlights the value of exome data reanalysis when a diagnosis is not initially apparent

Evolutionary Toxicology: Population-Level Effects of Chronic Contaminant Exposure on the Marsh Frogs (Rana ridibunda) of Azerbaijan

We used molecular methods and population genetic analyses to study the effects of chronic contaminant exposure in marsh frogs from Sumgayit, Azerbaijan. Marsh frogs inhabiting wetlands in Sumgayit are exposed to complex mixtures of chemical contaminants, including petroleum products, pesticides, heavy metals, and many other industrial chemicals. Previous results documented elevated estimates of genetic damage in marsh frogs from the two most heavily contaminated sites. Based on mitochondrial DNA (mtDNA) control region sequence data, the Sumgayit region has reduced levels of genetic diversity, likely due to environmental degradation. The Sumgayit region also acts as an ecological sink, with levels of gene flow into the region exceeding gene flow out of the region. Additionally, localized mtDNA heteroplasmy and diversity patterns suggest that one of the most severely contaminated sites in Sumgayit is acting as a source of new mutations resulting from an increased mutation rate. This study provides an integrated method for assessing the cumulative population impacts of chronic contaminant exposure by studying both population genetic and evolutionary effects

First Incursion of Salmonella enterica Serotype Typhimurium DT160 into New Zealand

An outbreak of human Salmonella enterica serotype Typhimurium DT160 infection in New Zealand was investigated from May to August 2001. Handling of dead wild birds, contact with persons with diarrheal illness, and consumption of fast food were associated with infection. Contaminated roof-collected rainwater was also detected