CRISPR/SpCas9-mediated KO of epigenetically active MORC proteins increases barley resistance to Bipolaris spot blotch and Fusarium root rot

Microrchidia (MORC) proteins are fundamental regulators of genome stabilization, chromatin remodeling and gene expression in both mammals and plants. In Arabidopsis, their activity is linked to the RNA-directed DNA methylation (RdDM) pathway, which utilizes small RNAs (sRNAs) to influence the rate of DNA methylation and chromatin compaction and thus gene expression. In barley, there are a total of seven members of the MORC family, and recent advances showed that HvMORC1 and HvMORC6a also interact with components of the RdDM pathway. CRISPR/SpCas9-mediated single and double knock-out mutants showed de-repression of transposable elements (TEs) and pathogenesis-related (PR) genes and interestingly increased resistance to both biotrophic and necrotrophic plant pathogenic fungi. In this study, we further demonstrate the requirement of MORC proteins in the resistance against two devastating cereal diseases, Bipolaris spot blotch, caused by Bipolaris sorokiniana and Fusarium root rot, caused by Fusarium graminearum.