CRISPR knockout reveals dual role of DMR6 in grapevine

Abstract

Grapevine (Vitis vinifera) faces increasing pressure from combined abiotic and biotic stressors. Achieving dual stress tolerance through editing of a single target offers a promising strategy for the development of robust, climate-resilient crops. Several studies have reported on the successful inactivation of host susceptibility genes for obtaining improved disease resistance in grapevine. Specifically, silencing of the well-described DOWNY MILDEW RESISTANT 6 (DMR6) gene leads to enhanced downy mildew (DM) resistance through the modulation of salicylic acid (SA) accumulation.

Beyond this, recent evidence has revealed that the inactivation of DMR6 also confers improved abiotic tolerance in tomato and potato. Therefore, the present analysis investigated whether editing of VvDMR6.1 could extend to abiotic stress resilience. VvDMR6.1-edited plants were obtained through CRISPR/Cas9-genome editing and Vvdmr6.1-mutant lines were assessed for DM resistance and subjected to water deficit conditions. Physiological and molecular analyses revealed that mutant lines exhibit a distinct water-saving strategy, maintaining high stomatal conductance under well-watered conditions, while a significant decrease was observed under water limitation. This was accompanied by elevated abscisic acid (ABA) accumulation, upregulation of major ABAbiosynthesis genes (VvNCED1 and VvNCED3), and enhanced antioxidant defences (VvSOD, VvAPX, VvSTS). Additionally, VvDMR6.1-mutants demonstrated decreased susceptibility to DM, consistent with previous findings. Taken together, these results establish VvDMR6.1 as a promising target for developing dual-stress resilient cultivars.