The present invention relates to a genetic determinant which may comprise at least two copies of a combination of two closely linked RDR1 genes, which two closely linked RDR1 genes are inversely oriented, and which genetic determinant leads to virus resistance when present in a plant. In one embodiment, of the RDR1 genes in the combination is represented by SEQ ID NO: 1 or has at least 70% sequence identity, and one of the RDR1 genes in the combination is represented by SEQ ID NO: 3 or has at least 70% sequence identity; or one of the RDR1 genes in the combination encodes a protein represented by SEQ ID NO: 2 or a protein that has at least 70% sequence identity, and one of the RDR1 genes encodes a protein represented by SEQ ID NO: 4 or a protein that has at least 70% sequence identity.