Brassica oleracea plant, comprising a resistance gene to Mycosphaerella brassicicola, wherein said resistance gene provides a monogenic and dominant resistance to Mycosphaerella brassicicola, and wherein the resistance gene is derived from a Brassica oleracea plant, the seeds of which have been deposited at the American Type Culture Collection (ATCC Patent Depository, 10801 University Boulevard, Manassas, VA 20110, 10United States of America) on 1 March 2006 under number PTA- 7413, wherein said Brassica oleracea plant with a resistance to Mycosphaerella brassicicola, is obtained by a method comprising: a) providing Brassica oleracea plant PTA-7413; b) crossing Brassica oleracea plant PTA-7413 with a susceptible Brassica oleracea plant; (c) isolating from the progeny genomic DNA for detecting the presence of an introgression with the resistance gene using one or more specific inter simple sequence repeat (iSSR) primers selected from the group consisting of SEQ ID Nos. 1 to 5 to detect random amplified microsatellite polymorphisms (RAMPs) linked to the resistance gene; and; (d) selecting from the progeny a Brassica oleracea plant in which the presence of the introgression with the resistance gene has been demonstrated in step (c). wherein the random amplified microsatellite polymorphisms (RAMPs) are selected from the group consisting of - a fragment of 198 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 1 and SEQ ID No. 6; - a fragment of 360 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 2 and SEQ ID No. 6; - a fragment of 370 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 3 and SEQ ID No. 6; - a fragment of 230 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 4 and SEQ ID No. 6; - a fragment of 173 bp or 473 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 5 and SEQ ID No. 6; wherein SEQ ID No. 6 is an Operon RAPD ® primer from 10-mer kits A-01 to Z-20. a) providing Brassica oleracea plant PTA-7413; b) crossing Brassica oleracea plant PTA-7413 with a susceptible Brassica oleracea plant; (c) isolating from the progeny genomic DNA for detecting the presence of an introgression with the resistance gene using one or more specific inter simple sequence repeat (iSSR) primers selected from the group consisting of SEQ ID Nos. 1 to 5 to detect random amplified microsatellite polymorphisms (RAMPs) linked to the resistance gene; and; (d) selecting from the progeny a Brassica oleracea plant in which the presence of the introgression with the resistance gene has been demonstrated in step (c). wherein the random amplified microsatellite polymorphisms (RAMPs) are selected from the group consisting of - a fragment of 198 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 1 and SEQ ID No. 6; - a fragment of 360 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 2 and SEQ ID No. 6; - a fragment of 370 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 3 and SEQ ID No. 6; - a fragment of 230 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 4 and SEQ ID No. 6; - a fragment of 173 bp or 473 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 5 and SEQ ID No. 6; - a fragment of 198 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 1 and SEQ ID No. 6; - a fragment of 360 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 2 and SEQ ID No. 6; - a fragment of 370 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 3 and SEQ ID No. 6; - a fragment of 230 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 4 and SEQ ID No. 6; - a fragment of 173 bp or 473 bp using the combination of the inter simple sequence repeat (iSSR) primer of SEQ ID No. 5 and SEQ ID No. 6; wherein SEQ ID No. 6 is an Operon RAPD ® primer from 10-mer kits A-01 to Z-20.