Brassica - Wildarten als neue genetische Ressource für die Rapszüchtung

Abstract

The genetic base in the material which is available in rapeseed breeding is very limited in comparison with other crops such as wheat or maize which are used for a very long time by humans. Reasons for this are on the one hand that rapeseed (Brassica napus) is a crop in which plant breeding plays a larger role only since a few decades and on the other hand that Brassica napus is phylogenetically a very young species. But to permanently ensure a successful breeding, greatest possible genetic diversity is essential in the breeding material.Because rapeseed is an amphidiploid species that originated from a spontaneous hybridization between turnip rape (Brassica rapa, A-genome) and cabbage (Brassica oleracea, C-genome), it is possible to produce artificial crosses between the two parental species to establish new resynthesized rapeseed lines. Such lines can be used to find new alleles which can be of interest for rapeseed breeding. For the production of resynthesized rapeseed as C genome parent nearly always vegetable types of cabbage were used. But there are especially in the Mediterranean area, a number of Brassica oleracea wild types and closely related Brassica species which can potentially be used as parents for resynthesized rapeseed lines. These species show a large genetic variation. Their breeding potential is so far largely unexploited.The aim of this project was to make the genetic diversity of these wild species available for rapeseed breeding for the first time by using them as parent for the production of resynthesized rapeseed lines. Based on AFLP marker analysis it could be shown that resynthesized rapeseed lines created with Brassica oleracea wild types or wild species, usually show a much greater genetic distance to adapted rapeseed breeding material as resynthesized rapeseed lines created with vegetable forms. The agronomic characteristics of resynthesized rapeseed lines were investigated in field trials. As expected the per se performance of the resythesized lines was bad. But they showed a very wide variation in terms of their quality determining ingredients. Furthermore, test crosses were created with two adapted male sterile winter rapeseed varieties. In yield testings, these test crosses achieved an amazing good performance. Overall, the results of this work show, that the resynthezised rapeseed lines can be very interesting for use in rapeseed breeding especially those that were created with Brassica wild species.