Genome editing of <italic>BnMLO6</italic> gene by CRISPR/Cas9 for the improvement of disease resistance in <italic>Brassica napus </italic>L

Abstract

<p id="C3">Gene editing technology can modify the target gene efficiently and accurately, which opens up a new way for crop genetic improvement. <italic>Mildew resistance locus O</italic> (<italic>MLO</italic>) gene is a key negative regulator of plant defense against powdery mildew. Mutation of <italic>MLO</italic> gene can enhance plant resistance to powdery mildew, but whether it has the same function is not reported in oilseed rape. In this study, the relative expression analysis suggested that <italic>BnMLO6</italic> gene was induced by <italic>Sclerotinia sclerotiorum</italic>. To explore the potential role of <italic>BnMLO6</italic> gene in pathogen resistance, six homologous copies of <italic>BnMLO6</italic> gene mutated synchronously by CRISPR/Cas9 gene editing technology and <italic>mlo6-212</italic> mutant line was generated for further analysis. Genetic analysis revealed that CRISPR/Cas9 induced mutagenesis of <italic>BnMLO6</italic> gene could be stably inherited. In addition, <italic>mlo6-212</italic> mutant line indicated obvious resistance to powdery mildew in both field and greenhouse condition. The lesion area of <italic>mlo6-212</italic> mutant was reduced by 19.5% after 24 hours inoculation with <italic>S. sclerotiorum</italic>. Meanwhile, mutation of <italic>BnMLO6</italic> gene could stimulate the spontaneous accumulation of callose in leaves and activate ethylene and jasmonic acid transduction pathway. Thus, <italic>BnMLO6 </italic>gene was probably involved in multiple pathogen resistance pathways to negatively regulate resistance to powdery mildew and <italic>S. sclerotiorum</italic> in oilseed rape. The results not only provide theoretical basis for the study of <italic>BnMLO6</italic> involved resistance regulation of multiple pathogens, but also provide resistant resources and technical support for genetic improvement of disease resistance in oilseed rape.