Resistance to gray leaf spot in maize

A method of screening corn plants for the presence of gray leaf spot (GLS) disease resistance comprising:

• crossing a first corn plant comprising at least two GLS resistance loci selected from the group consisting of GLS resistance locus 1, GLS resistance locus 2, GLS resistance locus 3, and GLS resistance locus 4 to a second corn plant lacking said at least one of said GLS resistance loci;
• obtaining progeny seed;
• screening a population of progeny seed or plants grown therefrom for at least two nucleic acid sequences selected from the group consisting of SEQ ID NOs:
• 66 to 78;
• wherein said GLS resistance locus 1 is on chromosome 1 and identifiable using a first SNP marker characterized by SEQ ID NO:
• 66 or 67, said GLS resistance locus 2 is on chromosome 1 and identifiable using a second SNP marker characterized by a nucleic acid sequence selected from the group consisting of SEQ ID NOs:
• 68 to 70, said GLS resistance locus 3 is on chromosome 3 and identifiable using a third SNP marker characterized by a nucleic acid sequence selected from the group consisting of SEQ ID NOs:
• 71 to 76, and said GLS resistance locus 4 is on chromosome 7 and identifiable using a fourth SNP marker characterized by SEQ ID NO:
• 77 or 78;
• and
• wherein said at least two nucleic acid sequences identify a different GLS resistance locus selected from the group consisting of GLS resistance locus 1, GLS resistance locus 2, GLS resistance locus 3, and GLS resistance locus 4.