BREEDING FOR SHARKA RESISTANCE AND HIGH FRUIT QUALITY IN EUROPEAN PLUM (PRUNUS DOMESTICA L.) AT WEIHENSTEPHAN: BREEDING STRATEGY AND SELECTION TOOLS

In 2005, a breeding program for European plum (Prunus domestica) was established at the Technical University of Munich in Weihenstephan, Germany. Methods for increasing the yield of seedlings out of a given number of pollinated flowers as well as timesaving selection methods for different traits of interest have been developed which may help to answer important problems that plum production is faced with. The breeding program aims at combining durable and complete resistance against Plum pox virus (PPV), the causative agent of Sharka disease, with high fruit quality. As a source of Sharka resistance, descendants of the crossing combination `Ortenauer' $\times$ `Stanley' are used. They originate from the breeding program of the University of Hohenheim and show a hypersensitive reaction after inoculation with PPV. In order to exploit the possible sources of resistance and to combine them, a gene bank of Prunus domestica genotypes has been built up and screened for Sharka resistance to find new sources of both hypersensitivity resistance as well as quantitative resistance against PPV. Moreover, crossings between highly PPV sensitive genotypes are performed in order to create new sources of hypersensitivity resistance which can be used in further breeding cycles. To enhance the fruit quality level of Sharka resistant cultivars, crossings with large sized, specially coloured and exceptionally tasty plum genotypes originating from the Weihenstephan Prunus gene bank or from the Hohenheim breeding program are performed. Furthermore, P. domestica genotypes are crossed with large sized P. cerasifera and P. salicina selections. Some interspecific hybrids show strong resistance against the Prune rust caused by the fungus Tranzchelia pruni-spinosae. Resistance tests which allow the selection of European plum genotypes resistant to Monilinia ssp. infections leading to the well known Brown rot of the fruits are under development.     «

In 2005, a breeding program for European plum (Prunus domestica) was established at the Technical University of Munich in Weihenstephan, Germany. Methods for increasing the yield of seedlings out of a given number of pollinated flowers as well as timesaving selection methods for different traits of interest have been developed which may help to answer important problems that plum production is faced with. The breeding program aims at combining durable and complete resistance against Plum pox vir...     »