Review article: Complexity of late blight resistance in potato and its potential in cultivar improvement

Abstract

Late blight disease caused by Phytophthora infestans is one of the most destructive diseases of potato. In the host an arsenal of genes may contribute to the resistance against the pathogen. In the presently available cultivars besides the so called field resistance which is conditioned by an unknown number of minor genes, race specific resistance genes were introgressed. Recently, broad spectrum resistance genes were identified, isolated and incorporated in breeding programs. The inbreeding depression that is characteristic for potato and the different sexual crossability problems associated with the potential resistance gene sources further complicate the development of cultivars with durable late blight resistance. The task to produce genotypes with resistance is challenged also by the recent occurrence of rapidly changing genotypes of the pathogen which are able to reproduce also sexually nowadays worldwide. Due to its importance, the genetic background of late blight resistance is intensively studied. The growing number of isolated major resistance genes and other genes involved in resistance response, as well as the identified QTLs allow the development of molecular tools which may be effectively used in breeding. In this review the complex status of resistance in potato to P. infestans and the breeding aspects of it is discussed.