Molecular analysis of the chromosome V gene cluster controlling resistance to several pathogens in potato

MARANO, M.R.; WIRTZ, U.; WEI, F.; WANG, X.; KUANG, H.; LIU, J.; RENSINK, W.; IOBST, S.; ET. AL.

San Diego, California, Estados Unidos

Congreso; XII Conference- Plant and Animal Genome; 2004

Plant and Animal Genome

Clusters of genes that confer resistance to virus, fungus, nematodes and insects have been mapped on potato chromosome V between markers GP21 and GP179. This region harbors among other genes, Nb and Rx2, conferring resistance to Potato Virus X, and R1 conferring resistance to Phytophthora Infestans. We identified and developed an integrated genetic and physical map of the Nb-R1 region using molecular markers from the tetraploid cv potato Pentland Ivory and the hexaploid wild species Solanum demissum. Markers linked to the Nb locus were used to screen a deep-coverage S. demissum library. BACs contigs were assembled by fingerprint analysis. BLAST searches of BAC sequences spanning the ~800 Kb Nb-R1 region (corresponding to 2.4 cM) indicate the presence of 10 to 15 resistance gene candidates belonging to the NB-ARC family, as well as other genes involved in resistance responses, including those encoding transcription factors, homeodomain proteins, TIR domain proteins and F-box proteins. The presence of multiple resistance genes together with several genes involved in innate immunity suggests that some defense responses may be regulated by a mechanism in which genes encoding functionally interacting products are clustered facilitating coordination of their expression. Future analysis is needed to determine the function of each of the resistance gene candidates and the regulation of their expression.