Two CAPS markers predict Verticillium wilt resistance in wild Solanum species

Verticillium wilt of potato is a persistent problem in the USA and worldwide. The disease, which is caused primarily by the fungus Verticillium dahliae, is difficult to manage, causes yield losses, and contaminates soil for subsequent plantings. Control strategies based on host resistance are seen as long-term, stable solutions, but difficult to achieve given the genetic nature of the host and the challenges associated with resistance evaluations. To provide breeders with marker-assisted selection opportunities, we generated a pair of cleaved amplified polymorphic sequence molecular markers within the coding region of Ve2, a potato gene with homology to the tomato Ve1 gene that confers resistance to V. dahliae. The position of the marker was determined according to the consensus sequences of Ve2 homologs of wild Solanum species with resistance to V. dahliae. Marker testing indicated their broad applicability, being able to track the resistance to V. dahliae in progeny containing genetic information derived from species S. chacoense, S. brevicaule, S. berthaultii, S. tarijense, and S. tuberosum. Furthermore, the two isolates of V. dahliae used in our inoculation experiments differed in virulence and demonstrated specificity for some wild potato species. Experimentation leading to the development of the markers and tests of their usefulness against a wide range of diploid potato germplasm is presented.