ISHS Acta Horticulturae 577: VII International Symposium on Plum and Prune Genetics, Breeding and Pomology
THE IMPORTANCE OF HYPERSENSITIVITY FOR BREEDING PLUMS AND PRUNES RESISTANT TO PLUM POX VIRUS (SHARKA) |
| Author: | W. Hartmann |
| Keywords: | Plum pox virus, hypersensitivity, plum breeding |
| Abstract:
More and more fruit growers are unsatisfied with the resistance or tolerance of today cultivated plum cultivars to plum pox virus (PPV). This resulted from the quantitative resistance which is depending on climatic conditions. Absolute resistance for PPV by hypersensitivity was found in the new cultivar 'Jojo' which derivided from a crossing of 'Ortenauer' x 'Stanley'. A sister of 'Jojo' was taken as parent for resistance breeding ten years ago. Some progenies were tested for hypersensitivity. The quota of hybrids with hypersensitive reaction (HR) was high, but with different grade. 'Jojo' was used since 1996 in our resistance breeding. In crossing with 21 different parents we hope to get hybrids with different ripening time and market demands. For more information about the HR the cultivar 'Jojo' was infected with some infection methods. The results shows that the infection dose and also the defense reaction of the plant depending from plant size, is responsible for the degree of HR. The hypersensitive reaction belonged to the qualitative resistance. Based on our results we can not agree to a yes/no reaction like postulated so far, because we notice a gradual reaction induced by a genaccumulation and/or several genes. The real circumstances on such are unknown. Involved are short and long distance transport. For a durable absolute resistance we combined qualitative and quantitative resistance in our hybrids. | |
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