CHARACTERISATION OF DIFFERENT INTERACTIONS BETWEEN CULTIVARS OF STONE FRUITS AND PLUM POX VIRUS

Different interactions between cultivars of stone fruits and Plum pox virus (PPV) were observed and characterized in studies on resistance of plums, apricots and peaches to PPV. Immunity, resistance, susceptibility, tolerance and hypersensitivity of stone fruit cultivars were presented in papers published in reviewed and impacted journals. In many cases the description of cultivars was not correct or was even wrong, especially when objective methods of detection were not applied. Characterization of interactions between cultivar and virus and examples of interactions will be presented. Immune cultivars cannot be infected with PPV, and the virus is not multiplied in plants. Apricot cultivar Harlayne was proved to be immune to the six different strains and isolates of PPV. Resistant cultivars can be infected with PPV, but the virus multiplication and moving is limited, and artificially or naturally infected trees are recovering from infection during one or two years. Apricot cultivars Leronda, Stark Early Orange and Harval were proved to be resistant to PPV. PPV is multiplied in plant cells of susceptible cultivars and the virus is moving systematically all over the tree and can be detected in flowers, leaves, stems and fruits. Both, resistance and susceptibility are relative. Highly susceptible cultivars to PPV are, e.g., plum Prunus domestica, cv. Požegača, apricot cv. Karola or peach cv. Catherina. Fruits are showing heavy symptoms, often malformations. Tolerant cultivars are susceptible to the virus infection, PPV is multiplied in leaf tissue often in high rate, but the fruit yield and quality are almost not influenced or in low rate. Several peach (e.g., Suncrest, Canadian Harmony) and plum (e.g., Čačanská rodná) cultivars are tolerant to PPV. The hypersensitive cultivars are extremely susceptible to PPV, leaf cells infected by aphids necrotize and die, infection is eliminated. In case of massive infection by grafting the whole tree is dying. Infection can be also transferred from PPV infected graft through the hypersensitive cultivar, e.g., plum cv. Jojo into susceptible rootstock.