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"McDonald, Megan"
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Rule of three
In Acton, Oregon, sisters Alex, Stevie, and Joey take turns telling about their lives, including auditioning for the same part in the school musical, baking contest-worthy cupcakes, and becoming obsessed with \"Little Women.\"
Book
The cysteine rich necrotrophic effector SnTox1 produced by Stagonospora nodorum triggers susceptibility of wheat lines harboring Snn1
The wheat pathogen Stagonospora nodorum produces multiple necrotrophic effectors (also called host-selective toxins) that promote disease by interacting with corresponding host sensitivity gene products. SnTox1 was the first necrotrophic effector identified in S. nodorum, and was shown to induce necrosis on wheat lines carrying Snn1. Here, we report the molecular cloning and validation of SnTox1 as well as the preliminary characterization of the mechanism underlying the SnTox1-Snn1 interaction which leads to susceptibility. SnTox1 was identified using bioinformatics tools and verified by heterologous expression in Pichia pastoris. SnTox1 encodes a 117 amino acid protein with the first 17 amino acids predicted as a signal peptide, and strikingly, the mature protein contains 16 cysteine residues, a common feature for some avirulence effectors. The transformation of SnTox1 into an avirulent S. nodorum isolate was sufficient to make the strain pathogenic. Additionally, the deletion of SnTox1 in virulent isolates rendered the SnTox1 mutated strains avirulent on the Snn1 differential wheat line. SnTox1 was present in 85% of a global collection of S. nodorum isolates. We identified a total of 11 protein isoforms and found evidence for strong diversifying selection operating on SnTox1. The SnTox1-Snn1 interaction results in an oxidative burst, DNA laddering, and pathogenesis related (PR) gene expression, all hallmarks of a defense response. In the absence of light, the development of SnTox1-induced necrosis and disease symptoms were completely blocked. By comparing the infection processes of a GFP-tagged avirulent isolate and the same isolate transformed with SnTox1, we conclude that SnTox1 may play a critical role during fungal penetration. This research further demonstrates that necrotrophic fungal pathogens utilize small effector proteins to exploit plant resistance pathways for their colonization, which provides important insights into the molecular basis of the wheat-S. nodorum interaction, an emerging model for necrotrophic pathosystems.
Journal Article
Judy Moody, mood martian
\"In honor of Backwards Day, Judy Moody decides to turn that frown upside down, make lemonade out of lemons, and be nice to stinky little brothers. In fact, Judy becomes a NOT moody, cool-as-a-cucumber neat freak for one whole entire day. But when her combed hair, matching outfits, and good moods hang around for days after, her friends begin to worry. Could this smiley Judy be an imposter?\"--Amazon.com.
Book
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.
Journal Article
Cloudy with a chance of boys
While older sister Alex is trying to orchestrate a perfect first kiss with her heartthrob and younger sister Joey prefers frogs to boys, Stevie Reel wonders if she is ready for a boyfriend while being pursued by a new boy in her class.
Book
A thousand-genome panel retraces the global spread and adaptation of a major fungal crop pathogen
Human activity impacts the evolutionary trajectories of many species worldwide. Global trade of agricultural goods contributes to the dispersal of pathogens reshaping their genetic makeup and providing opportunities for virulence gains. Understanding how pathogens surmount control strategies and cope with new climates is crucial to predicting the future impact of crop pathogens. Here, we address this by assembling a global thousand-genome panel of Zymoseptoria tritici, a major fungal pathogen of wheat reported in all production areas worldwide. We identify the global invasion routes and ongoing genetic exchange of the pathogen among wheat-growing regions. We find that the global expansion was accompanied by increased activity of transposable elements and weakened genomic defenses. Finally, we find significant standing variation for adaptation to new climates encountered during the global spread. Our work shows how large population genomic panels enable deep insights into the evolutionary trajectory of a major crop pathogen.
Journal Article
Stink and the Midnight Zombie Walk
Stink and his friends try to earn money to buy the latest book in the Nightmare on Zombie Street series and go to the book release party.
Book
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.
Journal Article
Genetic mapping of Stb19, a new resistance gene to Zymoseptoria tritici in wheat
Key message
A new and dominant R gene
Stb1
9 is identified from a soft wheat cultivar ‘Lorikeet’ and was mapped on the distal region of chromosome 1DS. Two tightly linked KASP markers were also discovered and validated for molecular-assisted breeding programs.
A new R gene, designated as
Stb19
, provides resistance to
Zymoseptoria tritici
in wheat. This new dominant gene resides on the short arm of chromosome 1D, exhibiting complete resistance to three
Z. tritici
isolates, WAI332, WAI251, and WAI161, at the seedling stage. A genetic linkage map, based on an F
2:3
population of ‘Lorikeet’ and ‘Summit,’ found the
Stb19
gene at a 9.3 cM region on 1DS, closely linked with two Kompetitive Allele-Specific PCR markers, snp_4909967 and snp_1218021. Further, the two markers were tested and validated in another F
2:3
population and 266 different wheat accessions, which gave over 95% accuracy of resistance/susceptibility prediction. Combined with the physical location of the identified SNPs and the previous evidence of gene order on chromosome 1DS (centromere–
Sr45
–
Sr33
–
Lr21
–telomere),
Stb19
is proposed to be located between
Sr33
and
Lr21
. Thus, the newly discovered
Stb19
along with the KASP markers represents an increase in genetic resources available for wheat breeding resistance to
Z. tritici
.
Journal Article