Ergebnisse einer Diallelanalyse zur Vererbung der Resistenz gegenSynchytrium endobioticum (Schilb.) Perc., Pathotyp 1 (Dl) bei Kartoffeln (Solanum tuberosum L.)

Zusammenfassung Die Nachkommenschaften eines Diallels mit 10 Eltern, ohne reziproke Kreuzungen, wurden gegen Pathotyp 1 (Dl) des Kartoffelkrebses geprüft. Aufgrund der Aufspaltung in resistent und anf?llig lassen sich 5 genotypische Gruppen unterscheiden. Zwei Gruppen entsprechen in ihrer Resistenzvererbung dem einfaktoriellen Modell bei Autotetraploiden auf duplexer bzw. simplexer Basis. Der Nachweis von zwei weiteren Genotypen, die sich nicht einordnen lassen, l?t eine h?here genetische Varianz erkennen, als nach dem autotetraploiden Modell theoretisht zu erwarten ist. Die M?glichkeit der Identifizierung weiterer Genotypen wird nicht ausgeschlossen.

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Summary The progeny of a diallel cross between 10 clones of table potatoes were tested for resistance toSynchytrium endobioticum Pathotype 1. Of the 10 parent clones, 9 were resistant, based on the characteristic defence necrosis, and one was very susceptible. In total 45 hybrid and 10 selfed progenies were tested with 60–100 genotypes in each case. The mean performance of each clone was assessed using the percentages of resistant genotypes for all 9 combinations with other clones, and the selfs. The 10 clones are arranged in Table 1 according to their rankings for this parameter. Five groups of genotypes (I–V) can be recognized; these are significantly different from one another. The mean values of the selfs for individual groups, and the combinations with the susceptible parent are also given. From these results it can be concluded that the clones in Groups I–III inherited resistance as if controlled by a single major dominant gene in the simplex or duplex condition in the autotetraploid. The susceptible parent gave a nulliplex-type. The corresponding test results given in Table 2 confirm these conclusions. According to Table 1, clones (4) and (9) do not fit into Groups I and III. They have another genotype. Since the parents used here cover only a small range of possible genotypes, no generally valid statements can be made about the number of groups and the frequency of the genotypes in the groups for all cultivars and clones ofSolanum tuberosum. Inheritance studies of wart resistance by other authors confirm the assumption that further genotype groups may be identified. Greater genetic variation can be expected than is theoretically possible in the single factor model of autotetraploidy.