The invention relates to a rucola plant of the species Diplotaxis tenuifolia which may comprise a genetic determinant that leads to expression of resistance against Peronospora parasitica, which genetic determinant is obtainable from a Diplotaxis tenuifolia plant which may comprise said genetic determinant, representative seed of which was deposited with the NCIMB under deposit number NCIMB 41811. The invention further provides seeds that may grow into a plant that is resistant to Peronospora parasitica, to progeny of the rucola plant to propagation material suitable for producing the plant or seed and to parts of the plant and food products which may comprise the plant parts.
