Plant & Animal Genome IX Conference

Poster: Large Insert Libraries, Gene Isolation, Etc.
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MAP-BASED CLONING OF LATE BLIGHT RESISTANCE GENES IN WILD POTATO

¹ Department of Plant Pathology, University of Wisconsin, 1630 Linden Drive, Madison, WI 53706 USA

² USDA-ARS and Department of Plant Pathology, University of Wisconsin, 1630 Linden Drive, Madison, WI 53706 USA

³ Department of Horticulture, University of Wisconsin, 1575 Linden Drive, Madison, WI 53706, USA

Late blight is among the most devastating diseases threatening the potato crop worldwide. We have generated somatic hybrids between susceptible tetraploid potato and the highly resistant wild diploid Solanum bulbocastanum. Somatic hybrids are highly resistant to late blight and full resistance can be recovered from segregating populations of each of three backcross generations (BC1, BC2, BC3) to potato. We previously reported that late blight resistance maps between RFLP marker TG478/CT64 and RAPD marker G02 on the S. bulbocastanum chromosome 8. Several markers tightly linked to resistance have been used to screen a S. bulbocastanum BAC library of 92,160 clones (average insert size: 150kb; 12X genome equivalents). In each case, numerous BAC clones have been isolated. End sequencing, new probe isolation via PCR of BAC clone ends, and additional hybridizations have allowed contig development for the late blight resistance region. Nearing completion, the contig is expected to encompass 1Mb of DNA (~10-12 overlapping BAC clones) based on FISH analyses of pachytene chromosomes using BAC clones flanking resistance as probes. As many as four complete BAC clones from this contig will be fully sequenced. Large insert transformation experiments and additional mapping studies will be used to select BAC clones for sequencing. It is expected that one or more genes for resistance will be identified. This project is funded in part by NSF Plant Genome Project #DBI-9975866.