Expression profiling of Solanum chacoense diploid potato lines to identify candidate Colorado potato beetle (Leptinotarsa decemlineata) resistance genes

Analysis of the mapped reads showed that 496 transcripts are differentially expressed between resistant and susceptible plants at 16-wks post-transplant. Of these, 188 transcripts are down-regulated in resistant plants, as well as significantly enriched on chromosome 2, while up-regulated genes are distributed across the genome. Previously uncharacterized uridine diphosphate-glycosyltransferases and ethylene response transcription factors within the QTL region identified by bulk-segregant analysis are candidate genes for further analysis. The Colorado potato beetle resistant line S. chacoense USDA8380-1 (80-1) was crossed to the inbred, beetle susceptible S. chacoense line M6 and a F2 population segregating for beetle resistance was developed. Ten individuals exhibiting extreme beetle resistance and ten individuals with extreme susceptiblilty in a replicated field trial were selected for bulk segregant analysis. Three individuals in each bulk pool were also examined for differences in gene expression. Three biological replicates of the parental lines and the three susceptible and three resistant F2 lines (N=24) were grown in a growth chamber. RNA was extracted from the lines at 16-wks post-transplant.