Argentinian wild diploid Solanum species as sources of quantitative late blight resistance

Greenhouse and field evaluations of quantitative resistance to late blight in genotypes of the wild Argentine diploid species Solanum chacoense, Solan um commersonnii, Solanum microdontum and Solanum maglia were performed with a complex race containing the virulence factors 1, 3, 4, 5, 7,10, 11 of Ph ytophora infestans and using the percentage of leaf area affected by late b light estimated at weekly intervals. From these readings the area under the disease progress curve (AUDPC) was calculated. Highly resistant and suscep tible genotypes were identified. Resistance and variability were found in S . chacoense, which together with S. commersonnii showed a significantly hig her level of resistance compared to the susceptible checks. Field evaluatio ns of an F-1 progeny of 165 individuals, obtained from non-inbred diploid p arents segregating for foliage quantitative resistance in S. chacoense, wer e also done by means of AUDPC. The polygenic nature of the resistance and s ome indication of the presence of both additive and interaction effects wer e evident.