Early HISTORY OF POTATO BREEDING FOR LATE BLIGHT RESISTANCE – A REVIEW

Abstract

The dramatic appearance of late blight in Europe in 1845 and during the subsequent years has led to the development of efficient plant pathology and potato breeding strategies. Variety Champion was a milestone in the early history of breeding for quantitative blight resistance, governed by polygenes. The visual selection of least blighted clones from gene pool of cultivated potato by private breeders led to insufficient results. Detection of simple inherited qualitative late blight resistance in wild potato material brought on intensive phyto-pathological and breeding work in public financed institutes. Expeditions to South and Middle America resulted in establishment of gene banks for potato species, increased knowledge of its blight resistance status and other traits and its use in breeding. Interspecific hybrids included mainly S. demissum as source of resistance possessing R genes, and these were used to breed varieties released after 1930. Occurrence of races of P. infestans could be identified since 1932 by differentials possessing different dominant R-genes. Now one could distinguish between qualitative (R-gene coded hypersensitivity) and quantitative resistance. Laboratory methods for assessment of resistance were developed mainly on foliage, but also on tubers and were widely applied. Rapid development of new virulent races of blight pathogen as well as increased expenditures to combine several R-genes made race specific resistance breeding inopportune. Recently the application of oomycides has become the main measure of protection.