ISBN: 9054858133 9789054858133

Category: Unavailable

Page count: 127

The vast majority of the present day leek cultivars is of poor quality. The genetic constitution of leek makes it a difficult crop to breed and consequently mass, or family selection methods, both of which have a low efficiency, are mainly used. F 1 hybrid breeding seems the appropriate strategy for improvement of leek. With such a breeding system a higher uniformity of the crop, better fixation of desirable traits, such as pest and disease resistance and a better exploitation of heterosis effects can be achieved. Large-scale seed production of hybrid cultivars requires a hybridization system based on cytoplasmic male sterility (CMS), because of the considerable advantage of this system in maintaining the male sterile parent line. Since no source of CMS has yet been found in leek or related forms of A. ampeloprasum , several researchers are focused on introducing cytoplasmic male sterility into leek. In the present thesis the possibility of introducing CMS into leek via somatic hybridization with A. cepa as CMS donor was investigated. Successful application of such a technique requires an efficient system for regeneration of plants from protoplasts. At the beginning of the research project in 1990 such a protoplast-to-plant system for leek was not available. Therefore, substantial effort was directed towards the development of efficient plant regeneration methods from embryogenic callus cultures, suspension cultures and protoplasts.