nucleic acid, nucleic acid sequence, recombinant DNA construction, vector, plasmid, bacterial cells, recombinant plant genome, plant cells, plant, seed and processes to obtain plants with reduced susceptibility to a pathogen, to protect cultivated plants against infection of pathogens, to isolate a nucleic acid, to enlarge the selective restriction fragment to identify a nucleic acid, and to detect the presence or absence of an oligonucleotide DNA sequence, primer combination, diagnostic kit, polypeptide and rna.