Improving resistance to late blight (Phytophthora Infestans) by using interspecific crosses in potato (Solanum Tuberosum ssp.)

Late blight (Phytophthora infestans) (P.i.) is the most serious disease in potato production worldwide and causes tremendous losses in yield and high costs in chemical plant protection. A worthwhile approach to combat the disease is breeding for late-blight resistance. Wild species of potato are potential sources of P.i.- resistance genes. In the past, though, genes conferring race-specific resistance were rapidly overcome due to the extremely high adaptation rate of the pathogen. An alternative strategy in breeding for resistance is to use quantitative or non-specific resistance allowing the survival of late blight on a low level without genetic adaptation. In a long-term breeding programme at Groß Lüsewitz Experimental Station, several wild species have been used for many years. In 2007 and 2008 a series of advanced breeding clones from a backcross programme involving different wild relatives were investigated for their reaction to late blight. A maturitycorrected score was used to separate resistance and late-maturity effects. We describe 11 breeding clones which display higher degrees of quantitative P.i.- resistance in the field combined with earlier maturity as compared to standard varieties. Besides, the clones showed high resistance against tuber blight, too. Notably, besides improved resistance to P.i. these clones possess acceptable agronomic traits with regard to starch content, suitability for crisp and chips production and acceptable levels of table quality, respectively.