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Poster: Biology & Disease Mgmt: Genetics of Resistance


Melampsora rust running amuck: Exploring willow rust population diversity in the Northeast United States.
C. CROWELL (1), M. Bekauri (1), C. Carlson (2), F. Gouker (2), L. Smart (2), C. Smart (1) (1) Cornell University Plant Pathology and Plant-Microbe Biology Section, U.S.A.; (2) Cornell University Horticulture Section, U.S.A.

Shrub Willow (Salix spp.) has proved to be a reliable short-rotation coppice (SRC) biofuel feedstock in the Northeast United States. However, the willow rust pathogen Melampsora spp. can cause up to a 50% reduction in yield, making some growing operations economically limited. This has spurred investigation into both the identification of resistance within in Salix spp. and the diversity of Melampsora spp. in the Northeast. Approximately 200 single pustule isolates were collected from MI, NY, PA, VT, and WV, and are being characterized by rDNA sequencing. Preliminary data shows that both M. americana and M. paradoxa are present in our regions of interest. Further investigation of Melampsora spp. diversity throughout the Northeast will be conducted using genotyping-by-sequencing, a genome wide high-throughput SNP identification method, providing thousands of markers for population studies targeting un-methylated coding sequences. Additionally, we explored disease resistance by characterizing association and linkage mapping populations of Salix purpurea with the aim of identifying QTL and tightly-linked SNPs for marker-assisted selection. Preliminary data show a continuum of resistance, suggesting promising breeding opportunities. This information will lead to further understanding of the population biology of Melampsora willow rust, while providing crucial information necessary for the success of future willow breeders.