CRISPR/Cas9-targeted mutagenesis of the tomato susceptibility gene PMR4 for resistance against powdery mildew

作者：Miguel I. Santillán Martínez, Valentina Bracuto, Eleni Koseoglou, Michela Appiano, E. Jacobsen, Richard G. F. Visser, Anne‐Marie A. Wolters, Yuling Bai · 发表于：BMC Plant Biology · 年份：2020 · DOI：10.1186/s12870-020-02497-y · 被引用次数：224 · 研究领域：CRISPR and Genetic Engineering、Powdery Mildew Fungal Diseases、Plant-Microbe Interactions and Immunity

BACKGROUND: The development of CRISPR/Cas9 technology has facilitated targeted mutagenesis in an efficient and precise way. Previously, RNAi silencing of the susceptibility (S) gene PowderyMildewResistance 4 (PMR4) in tomato has been shown to enhance resistance against the powdery mildew pathogen Oidium neolycopersici (On). RESULTS: To study whether full knock-out of the tomato PMR4 gene would result in a higher level of resistance than in the RNAi-silenced transgenic plants we generated tomato PMR4 CRISPR mutants. We used a CRISPR/Cas9 construct containing four single-guide RNAs (sgRNAs) targeting the tomato PMR4 gene to increase the possibility of large deletions in the mutants. After PCR-based selection and sequencing of transformants, we identified five different mutation events, including deletions from 4 to 900-bp, a 1-bp insertion and a 892-bp inversion. These mutants all showed reduced susceptibility to On based on visual scoring of disease symptoms and quantification of relative fungal biomass. Histological observations revealed a significantly higher occurrence of hypersensitive response-like cell death at sites of fungal infection in the pmr4 mutants compared to wild-type plants. Both haustorial formation and hyphal growth were diminished but not completely inhibited in the mutants. CONCLUSION: CRISPR/Cas-9 targeted mutagenesis of the tomato PMR4 gene resulted in mutants with reduced but not complete loss of susceptibility to the PM pathogen On. Our study demonstra...