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Title: Molecular characterization of Stenocarpella maydis based on nuclear ribosomal Internal Transcribed Spacer regions between the 18S and 28S nuclear rRNA gene sequences

Author
item FESSEHAIE, A - IOWA STATE UNIVERSITY
item Block, Charles
item SHEPHERD, L - IOWA STATE UNIVERSITY
item MISRA, M - IOWA STATE UNIVERSITY

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/4/2007
Publication Date: 8/1/2007
Citation: Fessehaie, A., Block, C.C., Shepherd, L.M., Misra, M.K. 2007. Molecular characterization of Stenocarpella maydis based on nuclear ribosomal Internal Transcribed Spacer regions between the 18S and 28S nuclear rRNA gene sequences [abstract]. American Phytopathological Society Annual Meeting. 97:S35.

Interpretive Summary:

Technical Abstract: Diplodia ear rot of maize is caused by the fungus Stenocarpella maydis (syn. Diplodia maydis). Although considered a minor pathogen in the later 1900's, with the increased emphasis on conservation tillage, S. maydis has reestablished itself as an important ear and stalk rot pathogen. While S. maydis-affected corn in the United States has not been shown to contain mycotoxins, toxin-producing strains have been described in South Africa and Argentina. A recent outbreak in Argentina in 2003 resulted in high mortality of heifers grazing a contaminated field. In this study, we characterized 30 S. maydis strains collected across the major corn growing regions of the U.S. by sequencing the internal transcribed spacer region (ITS) between the nuclear ribosomal 16S and 28S rDNA regions. Sequence analyses of the ITS sequence data showed that the U.S. strains formed a distinct monophyletic clade. Three of the 10 South African strains (data from GenBank) clustered with this group, but seven other strains formed a separate, more heterogeneous clade. The U.S. S. maydis strains seem to be more uniform than the South African strains, but additional microbiological and molecular work is required to address the differences reported in the literature.