Characterization of Claviceps species pathogenic on sorghum by sequenceanalysis of the beta-tubulin gene intron 3 region and EF-1 alpha geneintron 4

摘要

The intron 3 region of the beta -tubulin gene, and intron 4 of the translation elongation factor gene were PCR-amplified, cloned, and sequenced to determine relationships among Claviceps species and characterize isolates of Claviceps causing ergot of sorghum in the USA and other countries. The beta -tubulin gene intron 3 region and intron 4 of the EF-1 alpha gene allowed clear differentiation of five species (C. africana, C. sorghicola, C. purpurea, C. fusiformis, and C. paspali), two of which (C. africana and C. sorghicola) are pathogens of sorghum, with almost no intraspecific variation observed among isolates. Claviceps isolates obtained from sorghum in the USA contained beta -tubulin gene intron 3 region sequences identical to those, of C. africana isolates from India, Australia, and South Africa. PCR primers were designed from unique sequences within the beta -tubulin intron 3 region that can differentiate the five Claviceps species used in this study. We describe primers that allow direct PCR detection of C. africana from honeydew produced on infected sorghum plants, providing a useful tool for analysis of field samples. The beta -tubulin gene intron 3 region and EF-1 alpha intron 4 should prove useful in phylogenetic and epidemiological studies of additional Claviceps species.