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    Simple and Efficient Transformation and Gene Editing of Marchantia polymorpha Spores
    (Wiley Periodicals LLC, 2025-05-27) Yorker RM; Deroles SC; Zhou Y; Tate JA; Davies KM; Albert NW
    Marchantia polymorpha (Marchantia) has become a model species for liverwort studies, owing to its rapid growth in vitro, ease of propagation, simple genetics, small genome, haploid-dominant life cycle, and because it is amenable to genetic transformation. Efficient transformation provides a foundation for many molecular and genetic analyses. The protocol described here is a simple and robust procedure for transforming Marchantia for a variety of applications, including gene overexpression and CRISPR genome editing. This simplified Agrobacterium tumefaciens-mediated transformation protocol targets spores, using common Agrobacterium strains GV3101 or EHA105, and overcomes challenges experienced in other methods. Spores are sterilized and distributed over sterile filter papers, which effectively retain spores and regenerating spores (known as sporelings). This approach enables the sporelings to be transferred to different agar growth media at different stages of transformation. A critical feature is preculturing the spores with acetosyringone (AS) prior to co-cultivation with Agrobacterium. This treatment profoundly enhances the transformation rate, particularly for Agrobacterium strain GV3101. GV3101 is preferred for its rapid growth rate, simple transformation, and lack of a recombinase (recA), stabilizing plasmids. The protocol is suitable for transforming Marchantia with constructs for CRISPR gene editing. Editing efficiency can be increased by introducing a heat-shock treatment during the transformation procedure, which increases the proportion of plants with larger edited sectors, facilitating mutant identification and propagation. Constructs and strategies for both overexpression and multiplex genome editing with sgRNA arrays using new and existing vectors are described. Using this spore transformation protocol for CRISPR gene editing, we routinely achieve 60% to 70% mutation rates, significantly reducing the effort required to generate and isolate mutants for functional analyses.
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    Targeted Gene Mutations in the Forest Pathogen Dothistroma septosporum Using CRISPR/Cas9.
    (8/04/2022) McCarthy HM; Tarallo M; Mesarich CH; McDougal RL; Bradshaw RE
    Dothistroma needle blight, caused by Dothistroma septosporum, has increased in incidence and severity over the last few decades and is now one of the most important global diseases of pines. Disease resistance breeding could be accelerated by knowledge of pathogen virulence factors and their host targets. However, this is hindered due to inefficient targeted gene disruption in D. septosporum, which is required for virulence gene characterisation. Here we report the first successful application of CRISPR/Cas9 gene editing to a Dothideomycete forest pathogen, D. septosporum. Disruption of the dothistromin pathway regulator gene AflR, with a known phenotype, was performed using nonhomologous end-joining repair with an efficiency of > 90%. Transformants with a range of disruption mutations in AflR were produced. Disruption of Ds74283, a D. septosporum gene encoding a secreted cell death elicitor, was also achieved using CRISPR/Cas9, by using a specific donor DNA repair template to aid selection where the phenotype was unknown. In this case, 100% of screened transformants were identified as disruptants. In establishing CRISPR/Cas9 as a tool for gene editing in D. septosporum, our research could fast track the functional characterisation of candidate virulence factors in D. septosporum and helps set the foundation for development of this technology in other forest pathogens.