Screening of wild potato genetic resources for combined resistance to late blight on tubers and pale potato cyst nematodes

The Leibniz Institute of Plant Genetics and Crop Plant Research maintains a diverse collection of wild potato germplasm with more than 2800 accessions from 139 botanical species, 19 Solanum series and 14 countries of origin. During the past two decades, almost half of the collection has been screened for resistance to late blight (Phytophthora infestans) and pale cyst nematode (Globodera pallida (Pa2/3)) infection under laboratory conditions. In particular, resistance to tuber blight was considered, which is an important component of P. infestans resistance and has not been investigated that detailed yet. Out of the 1055 accessions tested, 68 were very resistant and 311 were classified as partially resistant against tuber blight. Besides in accessions of species well-known for foliage resistance, resistance to tuber blight was also observed in previously less reported species such as S. acaule, S. fendleri, S. megistacrolobum, S. polytrichon, S. jamesii, S. trifidum, and S. tarnii. In regard to G. pallida infection, 78 out of 749 tested accessions were classified as resistant, belonging to the species S. acaule, S. circaeifolium, S. gourlayi, S. kurtzianum, S. oplocense, S. sparsipilum, S. spegazzini and S. vernei. New or previously less reported sources of G. pallida resistance were identified in accessions of S. brevicaule, S. demissum and S. microdontum. In various accessions of different species, combined resistance was observed and the relationship to their country of origin is discussed.