Resistance to late blight (Phytophthora infestans) in ten wild Solanum species

Nineteen accessions of the tuber-bearing species Solanum berthaultii, S. chacoense, S. leptophyes, S. microdontum, S. sparsipilum, S. sucrense, S. venturii, S. vernei and S. verrucosum were tested for their resistance to late blight in two years of field experiments. Plants were artifically inoculated with zoospores of race 1.2.3.4.5.7.10.11 and the development of the disease was followed. Resistance ratings, calculated as the areas under the disease progress curves (ADPC), demonstrated a high resistance in all accessions except in S. sparsipilum, S. leptophyes and their interspecific hybrid. Segregations suggest that major genes for resistance are present in S. sucrense and S. venturii, and may also play a role in S. verrucosum. It is not yet certain wether the resistance of the other accessions is comparable to the partial and durable resistance of S. tuberosum cultivars like Pimpernel, as inheritance and mechanism have yet to be established. However, segregations suggesting the presence of single major genes with complete dominance were not found in these other accessions. Tuber initiation in the field occurred in only one accession, S. tuberosum ssp. andigena, and maturity of the clones was not related to their resistance. In the other accessions maturity types could not be assessed, as the clones require short day conditions for tuber initiation.

[1]  H. Toxopeus.  Some notes on the relations between field resistance to Phytophthora infestans in leaves and tubers and ripening time in Solanum tuberosum subsp. Tuberosum , 1958, Euphytica.

[2]  H. Toxopeus.  Treasure-digging for blight resistance in potatoes , 1964, Euphytica.

[3]  J. Malcolmson.  Phytophthora inpestans A2 compatibility type recorded in Great Britain , 1985 .

[4]  H. Hohl,et al.  Strains of Phytophthora infestans from Switzerland with A2 mating type behaviour , 1984 .

[5]  Jean F. Malcolmson,et al.  New R genes in Solanum demissum lindl. And their complementary races of Phytophthora infestans (Mont.) de bary , 1966, Euphytica.

[6]  D. S. Shaw,et al.  Occurrence of the rare A2 mating type of Phytophthora infestans on imported Egyptian potatoes and the production of sexual progeny with A1 mating types from the UK , 1985 .

[7]  Jean F. Malcolmson,et al.  Races of Phytophthora infestans occurring in Great Britain , 1969 .

[8]  N. Simmonds,et al.  Resistance to late blight inAndigena potatoes , 1967, European Potato Journal.

[9]  W. Hondelmann,et al.  Taxonomische und Resistenz-Untersuchungen an Kartoffel-Wildarten und -Primitivformen der deutsch-niederländischen Sammelreise in Bolivien 1980 , 1983 .

[10]  B. Nilsson.  Component analysis of general resistance toPhytophthora infestans in clones from the Colombian potato collection , 1981, Potato Research.

[11]  G. Shaner.  The Effect of Nitrogen Fertilization on the Expression of Slow-Mildewing Resistance in Knox Wheat , 1977 .

[12]  William E. Fry,et al.  Quantification of General Resistance of Potato Cultivars and Fungicide Effects for Integrated Control of Potato Late Blight , 1978 .

[13]  G. W. Snedecor.  STATISTICAL METHODS , 1967 .

[14]  M. Tazelaar,et al.  Resistance toPhytophthora infestans in tuber-bearing species ofSolanum and its geographical distribution , 1984, Potato Research.