Macroarray Detection of Solanaceous Plant Pathogens in the Fusarium solani Species Complex

Members of the Fusarium solani species complex (FSSC), which are morphologically similar but have more than 45 distinct lineages, were chosen as targets for the development of a macroarray detection system that would be broadly adaptable. Thirty-three oligonucleotides (17 to 27 mers) were designed from the internal transcribed spacer (ITS) of the ribosomal RNA genes of 17 FSSC isolates, which belong to 12 phylogenetically closely related species. Of the 33 oligonucleotides on the array, 21 were useful in discriminating all 12 species, some of which had only a single nucleotide difference among them. The high specificity of this method was achieved by optimizing the hybridization temperature and oligo probe length, which had a more substantial effect on the array performance than the melting temperature and the DNA G+C content (G/C%) of the probes. The array was validated by testing inoculated greenhouse samples and diseased field plant samples.