Identifikation von „Qualitäts“-Chromosomen in <em>Vitis</em> zur Frühdiagnose von Weinqualität

Abstract

The most severe pathogens in viticulture were introduced to Europe from North America in the 19^th century. For their control, American and Asian wild species are used in grapevine breeding as donors of resistances. The wild species are crossed with the European wine grape Vitis vinifera subsp. vinifera aiming at the combination of resistances and high quality. Grapevine breeding is hampered by a long generation time, repeated crosses with quality parents, as well as a timely and costly evaluation. Besides numerous undesired traits, wild species often feature dominant “off-flavors”. The most pronounced “foxy flavor” is mainly found in the wild species Vitis labrusca. “Foxiness” is caused by the key aroma compounds furaneol and methyl anthranilate that are perceivable as a mix of the “strawberry” and the “mothball” odor, respectively. Selected hybrids and two cross progenies of the North American species Vitis riparia, Vitis cinerea and Vitis labrusca were investigated with the focus on “off-flavors”. Their grapes and musts were investigated by organoleptics and analytics. The attained phenotypic and genotypic data were used for a subsequent QTL analysis. “Foxiness” was not typical for the investigated descendants of Vitis riparia and Vitis cinerea. For the identification of further “off-flavors”, gas chromatography combined with an olfactory detection was performed. These investigations elucidated intense vegetative flavors that were mainly assigned to substances of the methoxypyrazine class. The furaneol concentration was assumed to be dependent on the degree of berry ripeness. This could be confirmed by implementation of a method for targeted acceleration of berry ripening. A population originating from the cross `Blaufraenkisch´ (Vitis vinifera) x `Catawba´ segregates in the contents of furaneol and methyl anthranilate. In this population, the QTL analysis was based on a linkage map built from 337 simple sequence repeat markers and the amounts of the “foxy” aroma compounds. For furaneol and methyl anthranilate main QTLs were localized on the linkage group 11 and 4, respectively. In this population, additional QTLs for “slip skin” were identified on linkage groups 1 and 13. This Vitis labrusca typical berry trait could become relevant for grapevine breeding as well. The interspecific hybrid `Catawba´ is not only a parent of one investigated population, but also of particular historical interest. Moreover, the genetic investigations of `Catawba´ verified `Sémillon´ to be its Vitis vinifera parent. The results of this thesis contribute to improve the evaluation of genetic resources and their utilisation in grapevine breeding.