A review of host major-gene resistance to potato viruses X, Y, A and V in potato: genes, genetics and mapped locations.

In view of modern developments in the technologies available for breeding potatoes for resistance to virus diseases, it is timely to review the host major genes that confer resistance, in Solanum species, to potato viruses X, Y, A and V (the viruses for which the resistance genes have been most extensively studied). Over the course of 60 years, many such genes in Solanum species have been characterized: a comprehensive list is presented. Inheritance studies are reviewed, including linkage studies and molecular mapping, and the positions of resistance genes mapped so far are listed. It is apparent from recent research that disease resistance genes are often clustered in particular regions of the chromosomes; the significance of these resistance gene clusters is discussed. The information presented will be useful for potato breeding, and for genetic and mapping studies and gene cloning.