3 SELECTABLE MARKERS FOR TRANSFORMATION OF USTILAGO-MAYDIS

Although Ustilago maydis is readily amenable to molecular genetic experimentation, few antibiotic-resistance markers are available for DNA-mediated transformation. This poses constraints on experiments involving targeted gene disruption and complementation. To address this problem, we constructed vectors using one of three additional genes as dominant selectable markers for transformation. Two genes, sat-1 (encoding streptothricin acetyltransferase) and Sh-ble (encoding a phleomycin-resistance polypeptide), are of bacterial origin and have been engineered for expression in Ustilago sp. The third gene encodes an allele of U. maydis beta-tubulin that confers resistance to the fungicide benomyl.