Reduced susceptibility to downy mildew in grapevine plants edited for VvDMR6-1.

Grapevine downy mildew, caused by the oomycete Plasmopara viticola, is an important disease present in grapevine-growing areas worldwide. Current strategies of control rely on the use of fungicides, which is harmful for the environment and human health. Using resistant varieties is an environmentally friendly alternative to fungicides. Modification of plant susceptibility genes may lead to recessive resistance and CRISPR/Cas9 editing offers an opportunity to modify plant genes. Downy mildew resistant 6 (DMR6) from Arabidopsis thaliana is a negative regulator of plant immunity whose loss of function confers resistance to downy mildew. In grapevine, DMR6 is present in two copies, named VvDMR6-1 and VvDMR6-2. Here we describe the editing of VvDMR6-1 using CRISPR/Cas9 and show that edited plants are less susceptible to P. viticola and exhibit increased levels of salicylic acid.