Articles
THE RESISTANCE OF THE PLUM HYBRID K4 AND ITS PROGENIES TO PLUM POX VIRUS
PPV strains DI become systemic and cause mild leaf and fruit symptoms.
Free pollinated F1-progenies from K4 differ in regard to their reaction after graft inoculation with PPV. Some genotypes react hypersensitive like K4 but not all of them localize the virus: PPV-CG is detectible in the leaves and also in the bark.
All hypersensitive genotypes did not become naturally infected within 5 years.
Few other genotypes reacted with very mild symptoms, showed low virus titres and only single natural infections.
The rest of genotypes was more or less sensitive with moderate and severe symptoms, high and moderate virus accumulation and partial or total natural infection, respectively.
K4 seems suitable for differentiation of PPV-pathotypes, for selecting single PPV-free buds from infected trees, and for using as a source of PPV-resistance in plum breeding.